阅读说明：本技术 面向交直流混合供电方式的定制电力系统及其控制方法 (Customized power system facing alternating current-direct current hybrid power supply mode and control method thereof ) 是由 王凯亮 李俊辉 吴新雄 钟锦星 孔慧超 赵力 梁耀林 刘宗扬 余江盛 张育宾 廖 于 2021-07-15 设计创作，主要内容包括：本发明涉及一种面向交直流混合供电方式的定制电力系统及其控制方法,系统包括第一直流母线分段、第二直流母线分段和第三直流母线分段；以及第一交流母线分段、第二交流母线分段和第三交流母线分段；交流母线分段由对应的交流供电单元供电,并且交流母线分段均通过变流器给对应的直流母线分段供电；还包括对电压连续性的敏感程度依次降低的第一类直流/交流负载、第二类直流/交流负载和第三类直流/交流负载,其中给第一交流母线分段供电和给第二交流母线分段供电的两个供电单元之间设置有快速切换开关,快速切换开关在二者中任一个供电单元发生暂降时启动切换,实现了对交直流混合供电方式下电能质量的综合治理和连续供电能力保障。(The invention relates to a customized electric power system facing an alternating current-direct current hybrid power supply mode and a control method thereof, wherein the system comprises a first direct current bus section, a second direct current bus section and a third direct current bus section; the first alternating current bus section, the second alternating current bus section and the third alternating current bus section; the alternating current bus sections are supplied with power by corresponding alternating current power supply units, and the alternating current bus sections supply power to corresponding direct current bus sections through the converters; the power supply system also comprises a first type direct current/alternating current load, a second type direct current/alternating current load and a third type direct current/alternating current load, wherein the sensitivity degree of the power supply system to the voltage continuity is reduced in sequence, a quick change-over switch is arranged between the two power supply units for supplying power to the first alternating current bus in a subsection mode and supplying power to the second alternating current bus in a subsection mode, the quick change-over switch starts switching when any one of the two power supply units is subjected to sag, and the comprehensive control and continuous power supply capability guarantee of the power quality in an alternating current and direct current hybrid power supply mode are achieved.)

1. The utility model provides a customization electric power system towards alternating current-direct current hybrid power supply mode which characterized in that includes:

a DC bus and an AC bus; the direct current bus comprises a first direct current bus section, a second direct current bus section and a third direct current bus section; the alternating current bus comprises a first alternating current bus section, a second alternating current bus section and a third alternating current bus section; the first direct current bus section is connected with the first alternating current bus section through a first converter, the second direct current bus section is connected with the second alternating current bus section through a second converter, and the third direct current bus section is connected with the third alternating current bus section through a third converter; the first converter, the second converter and the third converter are used for rectifying alternating current on an alternating current bus into direct current and supplying the direct current to the direct current bus, or inverting a power supply on a direct current side into alternating current to supply the alternating current to the alternating current bus when alternating current power supply is interrupted;

the power supply unit comprises a first alternating current power supply unit, a second alternating current power supply unit and a third alternating current power supply unit, the first alternating current power supply unit is connected with the first direct current bus in a segmented mode, the second alternating current power supply unit is connected with the second direct current bus in a segmented mode, and the third alternating current power supply unit is connected with the third direct current bus in a segmented mode; a fast change-over switch is arranged between the first alternating current power supply unit and the second alternating current power supply unit and is used for starting switching when the first alternating current power supply unit or the second alternating current power supply unit is in a temporary state;

an alternating current load unit and a direct current load unit; the direct current load unit comprises a first direct current load, a second direct current load and a third direct current load, wherein the sensitivity degree of the direct current load to voltage continuity is reduced in sequence; the alternating current load unit comprises a first type of alternating current load, a second type of alternating current load and a third type of alternating current load, wherein the sensitivity degree of the alternating current load unit to the power supply continuity is reduced in sequence; the first type of direct current load, the second type of direct current load and the third type of direct current load are respectively connected with the first direct current bus section, the second direct current bus section and the third direct current bus section in a one-to-one corresponding mode; the first type of alternating current load, the second type of alternating current load and the third type of alternating current load are respectively connected with the first alternating current bus section, the second alternating current bus section and the third alternating current bus section in a one-to-one correspondence mode.

2. The system according to claim 1, wherein the power supply unit further includes:

the hybrid energy storage unit is connected with the first direct current bus in a segmented manner; the hybrid energy storage unit is used for supplying power to the first direct current bus in a segmented manner when the first alternating current power supply unit temporarily drops;

the hybrid energy storage unit comprises a storage battery and a first superconducting energy storage subunit, wherein the storage battery is used for charging for standby discharge when the system operates normally, the first superconducting energy storage subunit is used for stabilizing direct-current voltage on the first direct-current bus section and eliminating direct-current ripples, and transient large-current compensation is carried out when the storage battery is put into operation so as to reduce the impact of the storage battery and prolong the service life of the storage battery;

the second direct-current bus section is also electrically connected with a second superconducting energy storage subunit, and the second superconducting energy storage subunit is used for stabilizing direct-current voltage on the second direct-current bus section and eliminating direct-current ripples.

3. The system according to claim 2, wherein the power supply unit further includes:

the generator set is electrically connected with the second alternating current bus segment and used for supplying power to the first alternating current bus segment, the second alternating current bus segment, the first direct current bus segment and the second direct current bus segment when the first alternating current power supply unit and the second alternating current power supply unit are both subjected to power supply interruption and the residual electric quantity of a storage battery connected to the first direct current bus is smaller than a first preset value;

and a first bus interconnection switch is arranged between the first alternating current bus section and the second alternating current bus section and is used for closing the first alternating current bus section and the second alternating current bus section when the generator set supplies power to the alternating current bus.

4. The AC/DC hybrid power supply system-oriented customized power system according to claim 2,

a second bus interconnection switch is arranged between the first direct current bus section and the second direct current bus section; the second bus tie switch is used for closing the first direct current bus section and the second direct current bus section after the first converter fails so as to enable the second direct current bus section to supply power to the first direct current bus section; or after the second converter fails, closing the first direct current bus section and the second direct current bus section so that the first direct current bus section supplies power to the second direct current bus section;

the hybrid energy storage unit is also used for supplying power to the first direct current bus in a segmented mode after the first converter fails and before the second bus interconnection switch is closed.

5. The customized power system for the alternating current-direct current hybrid power supply mode according to claim 3, wherein the power supply unit further comprises a photovoltaic power supply unit and/or a fan power supply unit; the photovoltaic power supply unit and/or the fan power supply unit are electrically connected with the third direct current bus in a segmented mode;

a third bus interconnection switch is arranged between the third alternating current bus section and the second alternating current bus section; the third bus interconnection switch is used for closing the third alternating current bus segment and the second alternating current bus segment when the first alternating current power supply unit and the second alternating current power supply unit are both subjected to power supply interruption, the energy storage of the first direct current bus segment and the energy storage of the second direct current bus segment are released completely, and the residual fuel of the diesel generator set is exhausted to be smaller than a second preset value, so that the third alternating current bus segment supplies power to all loads;

a fourth bus bar interconnection switch is arranged between the third direct current bus bar section and the second direct current bus bar section; and the fourth bus tie switch is used for closing the third direct current bus section and the second direct current bus section when the power supply amount of the photovoltaic power supply unit and/or the fan power supply unit to the third direct current bus section is larger than the wind and/or light energy consumption amount of a third direct current load, so that the photovoltaic power supply unit and/or the fan power supply unit supplies power to the second direct current bus section and the first direct current bus section.

6. The customized power system for the alternating-current/direct-current hybrid power supply mode according to claim 1, wherein a superconducting current limiter is connected in series to the first type of direct-current load, and the superconducting current limiter is used for limiting current flowing to the first type of direct-current load when a ground short circuit fault occurs, so that the load can continuously operate without tripping;

the second type of alternating current load comprises a harmonic sensitive load and a sag sensitive load; the harmonic sensitive load is connected with an active filter in parallel, and the active filter is used for filtering the voltage supplied to the harmonic sensitive load; the sag sensitive load is connected in series with a dynamic voltage restorer to cope with the influence of voltage sag or load impact on the sag sensitive load.

7. A method for controlling a customized electric power system for an ac/dc hybrid power supply system according to any one of claims 1 to 6, comprising:

when the first alternating current power supply unit, the second alternating current power supply unit and the third alternating current power supply unit are in a normal power supply state, the first converter is controlled to rectify alternating current on the first alternating current bus section into direct current and provide the direct current for the first direct current bus section, the second converter is controlled to rectify alternating current on the second alternating current bus section into direct current and provide the direct current for the second direct current bus section, and the third converter is controlled to rectify alternating current on the third alternating current bus section into direct current and provide the direct current for the third direct current bus section;

and if the first alternating current power supply unit or the second alternating current power supply unit has a sag, controlling the quick change-over switch to switch so that the second alternating current power supply unit supplies power to the first alternating current bus in a segmented mode, or the first alternating current power supply unit supplies power to the second alternating current bus in a segmented mode.

8. The method of controlling a customized power system according to claim 7, wherein the first dc bus section is further connected to a hybrid energy storage unit; after the first ac power supply unit is suspended, the method further includes:

controlling the hybrid energy storage unit to supply power to the first direct current bus segment, and controlling the first converter to invert direct current on the first direct current bus segment into alternating current to be supplied to the first alternating current bus segment;

and judging whether the difference value between the time duration of the first alternating current power supply unit subjected to sag and the half time supported by the hybrid energy storage unit is smaller than a preset range, if so, controlling the quick change-over switch to start switching, and externally supplying power to the first direct current bus section by the first alternating current power supply unit.

9. The method of controlling a customized power system according to claim 8, wherein the power supply unit further comprises a generator set electrically connected to the second ac bus segment; after the first alternating current power supply unit generates sag or power supply interruption, the method further comprises the following steps:

if the second alternating current power supply unit also generates sag or controls the quick change-over switch to start and switch over failure, and the residual electric quantity of a storage battery connected to the first direct current bus is smaller than a first preset value, the generator set connected to the second alternating current bus segment is controlled to start, and the first bus interconnection switch connected between the first alternating current bus segment and the second alternating current bus segment is controlled to be closed, so that the generator set supplies power to the first alternating current bus segment and the second alternating current bus segment.

10. The method of controlling a customized power system according to claim 8, further comprising:

if the first converter fails, controlling a second bus tie switch connected between the first direct current bus section and the second direct current bus section to be switched from an open state to a closed state so that the second direct current bus section supplies power to the first direct current bus section; and during the switching state of the second bus bar interconnection switch, controlling a hybrid energy storage unit to provide power supply support for the first direct current bus bar section.

Technical Field

The embodiment of the invention relates to the technical field of power electronics, in particular to a customized power system facing an alternating current-direct current hybrid power supply mode and a control method thereof.

Background

The quality of electric energy not only relates to the safe and economic operation of power grid enterprises, but also influences the safe operation of users and the product quality, and along with the development of modern science and technology, the requirement of power users on the quality of electric energy is continuously improved. The customized power technology is characterized in that modern power electronics and control technology are applied, a high-power electronics technology and a power distribution automation technology are combined, and the required power is configured for a user according to the requirements of the user on power reliability and power quality.

At the power consumption terminal, the direct current power supply mode is more and more widely applied due to the configuration of better accepting the access and energy storage of renewable electric energy such as wind power, photovoltaic and the like and higher power supply efficiency, and the alternating current and direct current hybrid power supply mode is also becoming a more efficient and energy-saving power supply mode. The traditional customized power technology aims at alternating current power supply, aims at improving the alternating current power supply quality, and urgently needs a mode of differential customization on alternating current and direct current sides along with the rise of an alternating current and direct current hybrid power supply mode.

Disclosure of Invention

The embodiment of the invention provides a customized power system facing an alternating current-direct current hybrid power supply mode and a control method thereof, which aim to realize the control of the power quality and the continuous power supply capability guarantee of a power supply mode with load differentiation on an alternating current side and a direct current side in the alternating current-direct current hybrid power supply mode.

In a first aspect, an embodiment of the present invention provides a customized power system for an ac/dc hybrid power supply mode, including:

a DC bus and an AC bus; the direct current bus comprises a first direct current bus section, a second direct current bus section and a third direct current bus section; the alternating current bus comprises a first alternating current bus section, a second alternating current bus section and a third alternating current bus section; the first direct current bus section is connected with the first alternating current bus section through a first converter, the second direct current bus section is connected with the second alternating current bus section through a second converter, and the third direct current bus section is connected with the third alternating current bus section through a third converter; the first converter, the second converter and the third converter are used for rectifying alternating current on an alternating current bus into direct current and supplying the direct current to the direct current bus, or inverting a power supply on a direct current side into alternating current to supply the alternating current to the alternating current bus when alternating current power supply is interrupted;

the power supply unit comprises a first alternating current power supply unit, a second alternating current power supply unit and a third alternating current power supply unit, the first alternating current power supply unit is connected with the first direct current bus in a segmented mode, the second alternating current power supply unit is connected with the second direct current bus in a segmented mode, and the third alternating current power supply unit is connected with the third direct current bus in a segmented mode; a quick change-over switch is arranged between the first alternating current power supply unit and the second alternating current power supply unit, and the change-over is started when the first alternating current power supply unit or the second alternating current power supply unit is in a temporary state;

an alternating current load unit and a direct current load unit; the direct current load unit comprises a first direct current load, a second direct current load and a third direct current load, wherein the sensitivity degree of the direct current load to voltage continuity is reduced in sequence; the alternating current load unit comprises a first type of alternating current load, a second type of alternating current load and a third type of alternating current load, wherein the sensitivity degree of the alternating current load unit to the power supply continuity is reduced in sequence; the first type of direct current load, the second type of direct current load and the third type of direct current load are respectively connected with the first direct current bus section, the second direct current bus section and the third direct current bus section in a one-to-one corresponding mode; the first type of alternating current load, the second type of alternating current load and the third type of alternating current load are respectively connected with the first alternating current bus section, the second alternating current bus section and the third alternating current bus section in a one-to-one correspondence mode.

Optionally, the power supply unit further includes:

the hybrid energy storage unit is connected with the first direct current bus in a segmented manner; the hybrid energy storage unit is used for supplying power to the first direct current bus in a segmented manner when the first alternating current power supply unit temporarily drops;

the hybrid energy storage unit comprises a storage battery and a first superconducting energy storage subunit, wherein the storage battery is used for charging for standby discharge when the system operates normally, the first superconducting energy storage subunit is used for stabilizing direct-current voltage on the first direct-current bus section and eliminating direct-current ripples, and transient large-current compensation is carried out when the storage battery is put into operation so as to reduce the impact of the storage battery and prolong the service life of the storage battery;

the second direct-current bus section is also electrically connected with a second superconducting energy storage subunit, and the second superconducting energy storage subunit is used for stabilizing direct-current voltage on the second direct-current bus section and eliminating direct-current ripples.

Optionally, the power supply unit further includes:

the generator set is electrically connected with the alternating current bus, and is used for supplying power to the first alternating current bus segment, the second alternating current bus segment, the first direct current bus segment and the second direct current bus segment when the first alternating current power supply unit and the second alternating current power supply unit are both subjected to power supply interruption and the residual electric quantity of a storage battery connected to the first direct current bus is smaller than a first preset value;

and a first bus interconnection switch is arranged between the first alternating current bus section and the second alternating current bus section and is used for closing the first alternating current bus section and the second alternating current bus section when the generator set supplies power to the alternating current bus.

Optionally, a second bus bar interconnection switch is arranged between the first dc bus bar segment and the second dc bus bar segment; the second bus tie switch is used for closing the first direct current bus section and the second direct current bus section after the first converter fails so as to enable the second direct current bus section to supply power to the first direct current bus section; or after the second converter fails, closing the first direct current bus section and the second direct current bus section so that the first direct current bus section supplies power to the second direct current bus section;

the hybrid energy storage unit is also used for supplying power to the first direct current bus in a segmented mode after the first converter fails and before the second bus interconnection switch is closed.

Optionally, the power supply unit further includes a photovoltaic power supply unit and/or a fan power supply unit; the photovoltaic power supply unit and/or the fan power supply unit are electrically connected with the third direct current bus in a segmented mode;

a third bus interconnection switch is arranged between the third alternating current bus section and the second alternating current bus section; the third bus tie switch is used for closing the third alternating current bus segment and the second alternating current bus segment when the first alternating current power supply unit and the second alternating current power supply unit are both subjected to power supply interruption, the stored energy of the first direct current bus segment and the stored energy of the second direct current bus segment are released completely, and the residual fuel of the diesel generator set is smaller than a second preset value, so that the third alternating current bus segment supplies power to all loads;

a fourth bus bar interconnection switch is arranged between the third direct current bus bar section and the second direct current bus bar section; and the fourth bus tie switch is used for closing the third direct current bus section and the second direct current bus section when the power supply amount of the photovoltaic power supply unit and/or the fan power supply unit to the third direct current bus section is larger than the wind and/or light energy consumption amount of a third direct current load, so that the photovoltaic power supply unit and/or the fan power supply unit supplies power to the second direct current bus section and the first direct current bus section.

Optionally, the first type of dc load is connected in series with a superconducting current limiter, and the superconducting current limiter is used for limiting current flowing to the first type of dc load when a ground short fault occurs, so as to ensure that the load operates continuously without tripping;

the second type of alternating current load comprises a harmonic sensitive load and a sag sensitive load; the harmonic sensitive load is connected with an active filter in parallel, and the active filter is used for filtering the voltage supplied to the harmonic sensitive load; the sag sensitive load is connected in series with a dynamic voltage restorer to cope with the influence of voltage sag or load impact on the sag sensitive load.

In a second aspect, an embodiment of the present invention provides a method for controlling a customized electric power system, which is used for controlling the customized electric power system facing the ac-dc hybrid power supply method in any one of the first aspect, and the method includes:

when the first alternating current power supply unit, the second alternating current power supply unit and the third alternating current power supply unit are in a normal power supply state, the first converter is controlled to rectify alternating current on the first alternating current bus section into direct current and provide the direct current for the first direct current bus section, the second converter is controlled to rectify alternating current on the second alternating current bus section into direct current and provide the direct current for the second direct current bus section, and the third converter is controlled to rectify alternating current on the third alternating current bus section into direct current and provide the direct current for the third direct current bus section;

and if the first alternating current power supply unit or the second alternating current power supply unit has a sag, controlling the quick change-over switch to switch so that the second alternating current power supply unit supplies power to the first alternating current bus in a segmented mode, or the first alternating current power supply unit supplies power to the second alternating current bus in a segmented mode.

Optionally, the first dc bus segment is further connected to a hybrid energy storage unit; after the first ac power supply unit is suspended, the method further includes:

controlling the hybrid energy storage unit to supply power to the first direct current bus segment, and controlling the first converter to invert direct current on the first direct current bus segment into alternating current to be supplied to the first alternating current bus segment;

and judging whether the difference value between the time duration of the first alternating current power supply unit subjected to sag and the half time supported by the hybrid energy storage unit is smaller than a preset range, if so, controlling the quick change-over switch to start switching, and externally supplying power to the first direct current bus section by the first alternating current power supply unit.

Optionally, the power supply unit further includes a generator set, and the generator set is electrically connected to the second ac busbar in a segment manner; after the first alternating current power supply unit generates sag or power supply interruption, the method further comprises the following steps:

if the second alternating current power supply unit also generates sag or controls the quick change-over switch to start and switch over failure, and the residual electric quantity of a storage battery connected to the first direct current bus is smaller than a first preset value, the generator set connected to the second alternating current bus segment is controlled to start, and the first bus interconnection switch connected between the first alternating current bus segment and the second alternating current bus segment is controlled to be closed, so that the generator set supplies power to the first alternating current bus segment and the second alternating current bus segment.

Optionally, the method further comprises:

if the first converter fails, controlling a second bus tie switch connected between the first direct current bus section and the second direct current bus section to be switched from an open state to a closed state so that the second direct current bus section supplies power to the first direct current bus section; and during the switching state of the second bus bar interconnection switch, controlling a hybrid energy storage unit to provide power supply support for the first direct current bus bar section.

The embodiment of the invention provides a customized electric power system facing an alternating current-direct current hybrid power supply mode and a control method thereof, wherein the customized electric power system comprises a first direct current bus section, a second direct current bus section, a third direct current bus section, a first alternating current bus section, a second alternating current bus section and a third alternating current bus section; the alternating current bus sections are supplied with power by corresponding alternating current power supply units, and the alternating current bus sections supply power to corresponding direct current bus sections through the converters; the system also comprises a first type direct current/alternating current load, a second type direct current/alternating current load and a third type direct current/alternating current load, wherein the sensitivity degree of the system to voltage continuity is reduced in sequence; the quick change-over switch is arranged between the two power supply units for supplying power to the first alternating current bus section and the second alternating current bus section, and the change-over is started when any one of the two power supply units is temporarily changed. The embodiment of the invention ensures that the alternating current power supply unit can supply power to both direct current load and alternating current load in the system when the alternating current power supply unit normally works or invert a power supply at a direct current side into alternating current to supply to the alternating current load when the alternating current power supply is interrupted by arranging the converter between the alternating current bus and the direct current bus; and a fast change-over switch is arranged between the alternating current power supply units of the two lines with higher sensitivity to voltage continuity, if the first alternating current power supply unit or the second alternating current power supply unit drops temporarily, the fast change-over switch is controlled to be switched, so that the second alternating current power supply unit supplies power to the first alternating current bus in a segmented mode, or the first alternating current power supply unit supplies power to the second alternating current bus in a segmented mode, the fast change-over switch and the converter realize the guarantee of the electric energy quality of alternating current power supply and simultaneously guarantee of the electric energy quality of direct current power supply, and therefore the control of the electric energy quality and the continuous power supply capability guarantee of the alternating current and direct current side load differential power supply mode are realized in the alternating current and direct current hybrid power supply mode.

Drawings

Fig. 1 is a schematic structural diagram of a customized power system facing an ac/dc hybrid power supply mode according to an embodiment of the present invention;

fig. 2 is a flowchart of a control method for customizing an electric power system according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The embodiment of the present invention provides a customized electric power system for an ac/dc hybrid power supply mode, fig. 1 is a schematic structural diagram of the customized electric power system for the ac/dc hybrid power supply mode provided in the embodiment of the present invention, and referring to fig. 1, the customized electric power system includes:

a DC bus and an AC bus; the direct current bus comprises a first direct current bus section 21, a second direct current bus section 22 and a third direct current bus section 23; the alternating current bus comprises a first alternating current bus section 11, a second alternating current bus section 12 and a third alternating current bus section 13; the first dc bus section 21 is connected to the first ac bus section 11 through the first converter 112, the second dc bus section 22 is connected to the second ac bus section 12 through the second converter 122, and the third dc bus section 23 is connected to the third ac bus section 13 through the third converter 132; the first converter 112, the second converter 122, and the third converter 132 are used to rectify the AC power on the AC bus into DC power and supply the DC power to the DC bus, or to invert the DC power into AC power for supply to the AC load when the AC power supply is interrupted (the first converter 112, the second converter 122, and the third converter 132 are AC/DC converters).

The power supply unit comprises a first alternating current power supply unit A1, a second alternating current power supply unit A2 and a third alternating current power supply unit A3, the first alternating current power supply unit A1 is connected with the first direct current bus segment 21, the second alternating current power supply unit A2 is connected with the second direct current bus segment 22, and the third alternating current power supply unit A3 is connected with the third direct current bus segment 23; a fast switch SSTS is arranged between the first alternating current power supply unit a1 and the second alternating current power supply unit a2, and switching is started when the first alternating current power supply unit a1 or the second alternating current power supply unit a2 is in a temporary state;

an alternating current load unit and a direct current load unit; the direct current load unit comprises a first direct current load 211, a second direct current load 221 and a third direct current load 231, wherein the sensitivity degree of the direct current load to voltage continuity is reduced in sequence; the alternating current load unit comprises a first type alternating current load 111, a second type alternating current load 121 and a third type alternating current load 131, wherein the sensitivity degree of the first type alternating current load, the second type alternating current load and the third type alternating current load are reduced in sequence; the first type of direct current load 211, the second type of direct current load 221 and the third type of direct current load 231 are respectively connected with the first direct current bus section 21, the second direct current bus section 22 and the third direct current bus section 23 in a one-to-one correspondence manner; the first type alternating current load 111, the second type alternating current load 121 and the third type alternating current load 131 are respectively connected with the first alternating current bus segment 11, the second alternating current bus segment 12 and the third alternating current bus segment 13 in a one-to-one correspondence manner.

Specifically, the power supply unit includes a first ac power supply unit a1, a second ac power supply unit a2, and a third ac power supply unit A3, which are external power supply lines for supplying power to users from a power grid. The AC motor and other loads powered by AC are divided into three grades according to the high-quality power supply degree and connected to three sections of AC bus sections powered by AC. The frequency conversion device without the switch power supply and other loads adopting direct current power supply are divided into three grades according to the high-quality power supply degree, the three grades are connected to three direct current buses of direct current power supply, such as a computer, 220V alternating current is provided during conventional alternating current power supply, the alternating current is firstly converted into direct current through the switch power supply, then the direct current is converted into alternating current with controllable frequency to supply power to a mainboard, a CPU and a display card, and the direct current load is formed after the switch power supply is cancelled.

The dc load unit and the ac load unit may be classified into L1 to L3 levels according to the degree of sensitivity to voltage continuity. The first type alternating current load 111 and the first type direct current load 211 correspond to L1-level loads; the second type alternating current load 121 and the second type direct current load 221 correspond to L2-level loads; the third type of ac load 131 and the third type of dc load 231 correspond to L3 class loads. The load of the L1 level is the load with the highest requirement on power supply continuity, mainly comprises temperature control or fire protection load of important industrial process equipment, and a large amount of scrapped products or major safety accidents can be caused once the power supply is interrupted; the load of the L2 level is a general sensitive load, cannot bear voltage sag or power supply interruption for a long time, and has certain pollution to a power grid or cannot bear power quality disturbance caused by the power grid. That is, the L2-type load may inject harmonics into the grid, and thus needs to be treated; or the operation of the power grid is influenced when the power grid has harmonic waves, so that the influence of the harmonic waves of the power grid needs to be prevented; or the self generates impact frequently, so the treatment is needed; or the power grid reclosing and lightning striking of the tower cause flickering, the user is influenced, and therefore customized equipment needs to be configured for prevention. The ac loads in the L2 class load can be divided into a harmonic sensitive load 1211 and a sag sensitive load 1212. The harmonic sensitive load 1211 may be connected in parallel with an active filter 1213, and the active filter 1213 may filter out the harmonic waves injected into the system by the device and prevent the influence of external harmonic waves on the harmonic sensitive load. The sag sensitive load 1212 may be connected in series with a dynamic voltage restorer 1214 to cope with the effects of voltage sag or load impact. The load of the L3 level is a common load and can bear the sag or power failure of an external power supply line.

A load switch can also be arranged between each load bus. As shown in fig. 1, the first type ac load 111 and the first ac busbar section 11 are directly provided with a switch K₁₁(ii) a A switch K is arranged between the harmonic sensitive load 1211 and the second alternating current bus section 12₁₂(ii) a A switch K is arranged between the sag sensitive load 1212 and the second alternating current bus section 12₁₃(ii) a A switch K is arranged between the third type AC load 131 and the third AC busbar section 13₁₅(ii) a First type DC load 211 and first DC bus segmentA switch K is arranged between 21₂₁(ii) a A switch K is arranged between the second type direct current load 221 and the second direct current bus section 22₂₂(ii) a A switch K is arranged between the third type of dc load 231 and the third dc bus segment 23₂₃。

And in an external power supply mode, three power supplies are adopted to respectively supply power to the three types of loads. Wherein a three-switch solid-state fast transfer switch SSTS is provided at the two incoming lines of the first ac power supply unit a1 and the second ac power supply unit a 2. The first ac power supply unit a1 supplies power to the first ac bus segment 11 after the line switch 201 and the switch S1 in the solid-state fast switch SSTS are closed. The second dc power supply unit a2 supplies power to the second ac bus segment 12 after the line switch 202 and the switch S2 in the solid state fast switch SSTS are closed. The third ac power supply unit a3 supplies power to the first ac busbar section after the line switch 203 is closed. When the voltage sag occurs in the first ac power supply unit a1, the fast switch SSTS can be switched fast (the switch S2 is closed), the second ac power supply unit a2 supplies power to the first dc bus segment 21, and when the sag disappears, the first ac power supply unit a1 is switched back; when the voltage sag occurs in the first ac power supply unit a1, the fast switch SSTS can be switched fast (the switch S2 is closed), the first ac power supply unit a1 supplies power to the second dc bus segment 22, and when the sag disappears, the fast switch SSTS is switched back to the second ac power supply unit a 2.

According to the customized power system facing the alternating current-direct current hybrid power supply mode, when the alternating current power supply units are in a normal power supply state, the converter is controlled to rectify alternating current on the alternating current bus section into direct current and provide the direct current to the direct current bus section, and if the first alternating current power supply unit or the second alternating current power supply unit temporarily drops, the quick change-over switch is controlled to switch, so that the second alternating current power supply unit supplies power to the first alternating current bus section, or the first alternating current power supply unit supplies power to the second alternating current bus section. The fast switch and the converter realize the control of the power quality of alternating current power supply, and simultaneously can also control the power quality of direct current power supply, thereby realizing the control of the power quality of a power supply mode with load differentiation at the alternating current side and the direct current side in an alternating current and direct current hybrid power supply mode.

Optionally, with continuing reference to fig. 1, the power supply unit further includes:

the hybrid energy storage unit 30, the hybrid energy storage unit 30 is connected with the first direct current bus segment 21; the hybrid energy storage unit 30 is used for supplying power to the first dc bus section 21 when the first ac power supply unit a1 is temporarily dropped;

the hybrid energy storage unit 30 comprises a storage battery 31 and a first superconducting energy storage subunit 32, wherein the storage battery 31 is used for charging for standby discharge when the system operates normally, the first superconducting energy storage subunit 32 is used for stabilizing direct-current voltage on the first direct-current bus section 21 and eliminating direct-current ripples, and transient large-current compensation is performed when the storage battery 31 is put into operation to reduce impact on the storage battery and prolong the service life of the storage battery;

the second dc bus segment 22 is further electrically connected to the second superconducting energy storage subunit 70, and the second superconducting energy storage subunit 70 is configured to stabilize the dc voltage on the second dc bus segment 22 and eliminate the dc ripple.

Specifically, the first AC load 111 requiring the highest power supply continuity is connected to the first AC bus segment 11, and when a sag or a power supply interruption occurs in an external power supply line of the first AC power supply unit a1, the first converter 112 (the first converter is an AC/DC converter) connected to the same bus is changed from a rectification state to an inversion state. The hybrid energy storage unit 30 formed by the storage battery 31 and the superconducting energy storage starts to discharge, and generates alternating current through inversion of the first converter to supply the alternating current to the first type alternating current load 111 for operation. The first converter 112 is in a rectifying state in a conventional mode, is in an inverting state when the storage battery 31 supplies power to the first type alternating current load 111, and can also realize short-time voltage compensation through reactive power control when the alternating current bus fluctuates, thereby playing the role of a static reactive power compensator. The second converter 122 is in a rectifying state in a conventional manner, and can also implement short-time voltage compensation through reactive power control when the voltage of the second ac bus segment 12 needs to be adjusted, so as to function as a static reactive power compensator.

If the duration of the sag or interruption of the power supply of the first ac power supply unit a1 is close to about half of the supportable power supply time of the hybrid energy storage unit 30, the fast switch SSTS is controlled to start switching, and the second ac power supply unit a2 supplies power to the external. The first dc bus segment 21 may be externally powered by the first ac power supply unit a1 by determining whether a difference between a duration of the sag of the first ac power supply unit a1 and a half of a time that the hybrid energy storage unit 30 can support is smaller than a preset range, and controlling the fast transfer switch SSTS to start switching if the difference is smaller than the preset range. The hybrid energy storage unit 30 can provide a buffering time for the first ac power supply unit a1 to resume normal operation, and can also avoid the occurrence of the situation that the fast switch SSTS is switched immediately as long as the first ac power supply unit a1 has a sag or power interruption, so as to reduce the switching frequency of the fast switch SSTS between the first ac power supply unit a1 and the second ac power supply unit a2, and ensure the service life of the fast switch SSTS.

In addition, the hybrid energy storage unit 30 is a modified UPS (uninterruptible power supply) including a storage battery 31 and a first superconducting energy storage subunit 32. When the customized power system normally operates, the storage battery 31 is fully charged and enters a floating charge and standby discharge mode; the first superconducting energy storage subunit 32 performs the functions of stabilizing the voltage of the first dc bus segment 21 and reducing the voltage ripple by performing timely adjustment through fast charging and discharging, similar to the dc DVR (dynamic voltage restorer 1214) and APF (active filter 1213). When the storage battery 31 needs to be put into operation quickly to guarantee uninterrupted power supply, the first superconducting energy storage subunit 32 provides instantaneous large current at the initial stage of discharge, so that the discharge power of the storage battery 31 is gradually increased to be balanced with the load, and the battery is protected. The second dc bus segment 22 is further electrically connected to a second superconducting energy storage subunit 70, and the second superconducting energy storage subunit 70 is configured to stabilize a dc voltage on the second dc bus segment 22. DC/DC converters may also be disposed between the hybrid energy storage unit 30 and the DC bus, and between the second superconducting energy storage subunit 70 and the DC bus.

Optionally, with continuing reference to fig. 1, the power supply unit further includes:

the generator set 40 is electrically connected with the second alternating current bus segment 12, and the generator set 40 is used for supplying power to the first alternating current bus segment, the second alternating current bus segment, the first direct current bus segment and the second direct current bus segment when the first alternating current power supply unit A1 and the second alternating current power supply unit A2 both have power supply interruption or temporary drop and the residual capacity of a storage battery connected to the first direct current bus is smaller than a first preset value;

a first busbar interconnection switch is arranged between the first ac busbar section 11 and the second ac busbar section 12, and the first busbar interconnection switch S1 is used to close the first ac busbar section 11 and the second ac busbar section 12 when the generator set 40 supplies power to the ac busbar.

Specifically, the first ac load 111 requiring the highest power supply continuity is connected to the first ac bus segment 11, and when a sag or a power supply interruption occurs in an external power supply line of the first ac power supply unit a1, the first converter connected to the same bus is changed from a rectification state to an inversion state. The hybrid energy storage unit 30 formed by the storage battery 31 and the superconducting energy storage starts to discharge, and generates alternating current through inversion of the first converter to supply the alternating current to the first type alternating current load 111 for operation. If the duration of the sag or interruption of the first ac power supply unit a1 approaches the sustainable power supply time of the hybrid energy storage unit 30 by about half, the fast switch SSTS starts switching to supply power from the second ac power supply unit a 2. If the second ac power supply unit a2 is also interrupted or the fast switch SSTS is not successfully switched, the generator set 40 on the ac bus is started, and the generator set 40 supplies power to the first dc bus section 21 and the second dc bus section 22 before the hybrid energy storage unit 30 finishes discharging. Wherein the genset 40 may be disposed on the second ac bus segment 12, a first bus tie switch S1 is disposed between the first ac bus segment 11 and the second ac bus segment 12, the first bus tie switch S1 is configured to close the first ac bus segment 11 and the second ac bus segment 12 when the genset 40 is supplying power to the ac bus. Normal work of the customized power system can be further ensured through the generator set 40, the quality of electric energy is controlled, and a switch K can be arranged between the generator set 40 and the alternating current bus₁₄。

Optionally, a second bus bar interconnection switch is arranged between the first dc bus bar segment 21 and the second dc bus bar segment 22; the second bus tie switch S2 is configured to close the first dc bus segment 21 and the second dc bus segment 22 after the first converter 112 fails, so that the second dc bus segment 22 supplies power to the first dc bus segment 21; or after the second converter 122 fails, the first dc bus segment 21 and the second dc bus segment 22 are closed, so that the first dc bus segment 21 supplies power to the second dc bus segment 22;

the hybrid energy storage unit 30 is also used to supply power to the first dc bus section 21 after the first converter 112 has failed and before the second bustie switch is closed.

Specifically, the first converter 112 and the second converter 122 are backup devices for each other, and function to supply power to the first dc load 211 and the second dc load 221. If the first converter 112 fails, controlling a second busbar interconnection switch S2 connected between the first dc bus segment 21 and the second dc bus segment 22 to switch from an open state to a closed state, so that the second converter 122 supplies power to the first dc bus segment 21; and during the second bustie switch switching state the hybrid energy storage unit 30 may provide voltage support to the first dc bus section 21. If the second converter 122 fails, the second busbar interconnection switch S2 connected between the first dc bus segment 21 and the second dc bus segment 22 can be controlled to switch from the open state to the closed state, so that the first converter 112 supplies power to the second dc bus segment 22. The time during which the first dc busbar section 21 and the second dc busbar section 22 are connected is extremely short, since there is no transient impact caused by phase differences between the dc busbar connections. During the switching of the second bus bar interconnection switch S2, the second dc load 221 can be subjected to a very short interruption, so that the voltage support of the battery 31 is not required; the battery 31 has a high cost and a limited configuration capacity, and is only used for backup of the first dc load 211.

The first-class direct-current load 211 with the highest requirement on power supply continuity is connected to the first direct-current bus section 21, the first converter normally supplies direct-current power in a rectification mode, and in order to prevent a load switch K21 connected between the first-class direct-current load 211 and the first direct-current bus section 21 from tripping due to overcurrent when the first-class direct-current load 211 has a single-phase ground short-circuit fault, a superconducting current limiter 212 is connected in series to a branch of the first-class direct-current load 211. The superconducting current limiter 212 is used for limiting current, so that the first type of direct current load 211 can be ensured to normally operate when a single-phase ground short circuit fault occurs. The storage battery 31 and the superconducting energy storage and superconducting current limiter 212 realize the power quality control of direct current power supply.

To sum up, the embodiment of the invention discloses a customized electric power system facing an alternating current-direct current hybrid power supply mode, which is characterized in that a fast switch is arranged between two power supply units for supplying power to a first alternating current bus section and a second alternating current bus section, and the fast switch is started to switch when any one of the two power supply units is subjected to temporary drop; the superconducting-battery hybrid energy storage configured on the first direct current bus is started to be switched to the most important load uninterrupted power supply on the first alternating current/direct current bus when the first alternating current/direct current bus is subjected to temporary drop or short-time power supply interruption, wherein the superconducting energy storage provides transient power type rapid compensation, and the battery energy storage provides energy compensation to form complementation; the first direct current bus is connected to a first class direct current load and connected in series with a superconducting current limiter to ensure that the current is not too large to cause tripping when the load is in short circuit; an active filter arranged on the second alternating current bus is used for filtering when the harmonic source injects the harmonic; the second alternating current bus is connected to a sag sensitive load, is connected in series with the dynamic voltage recovery device and is matched with an external fast change-over switch to manage voltage sag; the second alternating current bus is provided with a generator set for coping with long-time external power supply interruption; the superconducting energy storage is configured on the second direct current bus and used for governing direct current ripples and direct current voltage fluctuation; the configuration realizes the comprehensive treatment of the power quality in the AC/DC hybrid power supply mode.

Optionally, the power supply unit further includes a photovoltaic power supply unit 50 and/or a fan power supply unit 60; the photovoltaic power supply unit 50 and/or the fan power supply unit 60 are electrically connected with the third dc bus segment 23;

a third bus bar interconnection switch S3 is arranged between the third alternating current bus bar section 13 and the second alternating current bus bar section 12; the third bus tie switch S3 is configured to close the third ac bus segment 11 and the second ac bus segment 12 when the first ac power supply unit a1 and the second ac power supply unit a2 are both powered off, the energy storage of the first dc bus segment 21 and the energy storage of the second dc bus segment 22 are released, and the remaining fuel of the diesel generator set 40 is smaller than a second preset value, so that the third ac bus segment 13 supplies power to all loads;

a fourth bus tie switch is arranged between the third direct current bus section 23 and the second direct current bus section 22; the fourth bus tie switch is used for closing the third dc bus section 23 and the second dc bus section 22 when the power supply amount of the photovoltaic power supply unit 50 and/or the fan power supply unit 60 to the third dc bus section 23 is larger than the consumption amount of the third dc load to wind and/or light energy, so that the photovoltaic power supply unit 50 and/or the fan power supply unit 60 supplies power to the second dc bus section 22 and the first dc bus section 21.

Specifically, the distributed wind and light is connected in a direct current mode and consumed by the third direct current load 231 during normal operation, so that the utilization efficiency is improved. A DC/DC converter is arranged between the photovoltaic power supply unit 50 and the DC bus, and a DC/AC converter is arranged between the fan power supply unit 60 and the DC bus. The power of the third type of dc load 231 may be provided partially from distributed renewable energy, and in case of shortage, may be supplied from an external power supply line by rectification via the third converter 132. Or a portion may come from an external power supply line and, when insufficient, may come from a supply of distributed renewable energy. Or receive power from an external power supply line and distributed renewable energy at the same time, which is not limited herein. When the load L3 on the third section of direct current bus is not enough to consume the wind and light clean energy, the second type of direct current load 221 and the first type of direct current load 211 can be consumed through the segmented loop of the three sections of direct current buses. When three power supplies externally supplied by the photovoltaic power supply unit 50 and/or the fan power supply unit 60 are interrupted, the storage battery 31 can be assisted to prolong the uninterrupted power supply time; the photovoltaic power supply unit 50 and/or the fan power supply unit 60 can also cooperate with the hybrid energy storage unit 30 to play a role in regulation when the generator is in emergency power supply, so that renewable energy can be efficiently consumed to the maximum extent. The photovoltaic power supply unit 50 and/or the fan power supply unit 60 are connected to the dc bus, and the electric energy generated by the dc bus is directly consumed by the dc load, or the storage battery 31 and the superconducting energy storage (the first superconducting energy storage is in the unit 32 and the second superconducting energy storage subunit 70) are charged by the change of the operation mode, so that the storage battery is consumed by the dc load as much as possible, and the efficiency of the renewable energy consumption is improved. In addition, the third converter 132 may be provided to have an inverter state, and may convert the surplus renewable energy into ac power to supply to the third ac load 131.

According to the customized power system provided by the embodiment of the invention, under the alternating current-direct current hybrid power supply mode, the alternating current-direct current side is subjected to differential customization and targeted power quality control. The DVR, the active filter, the fast change-over switch and the AC/DC converter realize the electric energy quality control of the alternating current power supply; the storage battery, the superconducting energy storage, the superconducting current limiter, the fast change-over switch and the AC/DC converter realize the control of the electric energy quality of the direct current power supply. The superconducting current limiter ensures that the first type of direct current load can continuously operate under the condition of single-phase earth fault; the superconducting energy storage plays a role in eliminating direct current bus voltage ripples; the superconducting energy storage and the battery energy storage form a hybrid energy storage unit, initial large current is provided by the superconducting energy storage when the hybrid energy storage unit is put into use, the battery is ensured to gradually output power, and therefore the service life of the battery is prolonged. The topological structure of the converter determines the capability of four-quadrant operation, and the converter can utilize the function to have the capability of quickly generating/absorbing reactive power so as to support the voltage of an alternating-current bus. Discrete wind power is connected to a direct-current voltage bus after direct-current conversion through direct-drive motor rectification and distributed photovoltaic, direct consumption is achieved through a direct-current load, or storage batteries and superconducting energy storage are charged through conversion of an operation mode, so that the storage batteries and the superconducting energy storage are consumed by the direct-current load as much as possible, and the efficiency of renewable energy consumption is improved.

An embodiment of the present invention further provides a control method for a customized power system, which is used to control the customized power system facing the alternating current/direct current hybrid power supply manner described in any of the above embodiments, where fig. 2 is a flowchart of the control method for the customized power system provided in the embodiment of the present invention, and with reference to fig. 2, the method includes:

and S110, when the first alternating current power supply unit, the second alternating current power supply unit and the third alternating current power supply unit are in a normal power supply state, controlling the first converter to rectify alternating current on the first alternating current bus section into direct current and provide the direct current to the first direct current bus section, controlling the second converter to rectify alternating current on the second alternating current bus section into direct current and provide the direct current to the second direct current bus section, and controlling the third converter to rectify alternating current on the third alternating current bus section into direct current and provide the direct current to the third direct current bus section.

And S120, if the first alternating current power supply unit or the second alternating current power supply unit has a sag, controlling the quick change-over switch to switch so that the second alternating current power supply unit supplies power to the first alternating current bus in a segmented mode, or enabling the first alternating current power supply unit to supply power to the second alternating current bus in a segmented mode.

Optionally, the first dc bus segment is further connected to the hybrid energy storage unit; after the first ac power supply unit has sagged, the method further includes:

controlling a hybrid energy storage unit to supply power to the first direct current bus section, and controlling a first converter to invert direct current on the first direct current bus section into alternating current to be supplied to the first alternating current bus section;

and judging whether the difference value between the time duration of the first alternating current power supply unit subjected to sag and the half time supported by the hybrid energy storage unit is smaller than a preset range, if so, controlling the quick change-over switch to start switching, and externally supplying power to the first direct current bus section by the first alternating current power supply unit.

Optionally, the power supply unit further includes a generator set, and the generator set is electrically connected to the second ac bus in a segmented manner; after the first ac power supply unit has a sag or a power supply interruption, the method further includes:

if the second alternating current power supply unit also generates sag or controls the quick change-over switch to start and switch over failure, and the residual electric quantity of the storage battery connected to the first direct current bus is smaller than a first preset value, the generator set connected to the second alternating current bus segment is controlled to start, and the first bus interconnection switch connected between the first alternating current bus segment and the second alternating current bus segment is controlled to be closed, so that the generator set supplies power to the first alternating current bus segment and the second alternating current bus segment.

Optionally, the method further comprises:

if the first converter fails, controlling a second bus tie switch connected between the first direct current bus section and the second direct current bus section to be switched from an open state to a closed state so that the second direct current bus section supplies power to the first direct current bus section; and during the switching state of the second bus bar interconnection switch, the hybrid energy storage unit is controlled to provide power supply support for the first direct current bus bar section.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.