Converter based on three-port distributed photovoltaic energy storage hybrid structure
阅读说明：本技术 基于三端口分布式光伏储能混合结构的变换器 (Converter based on three-port distributed photovoltaic energy storage hybrid structure ) 是由 陈超 阙波 周金辉 苏毅方 马振宇 邓焰 阮杰 李广地 于 2019-08-16 设计创作，主要内容包括：本发明公开了一种基于三端口分布式光伏储能混合结构的变换器。本发明采用单星型拓扑结构,其包括储能介质部分、功率级部分以及LCL滤波部分；所述的储能介质部分包括储能电池和光伏阵列；所述的功率级部分包括直流侧防反二极管、由多个功率开关组成的三相桥臂结构以及双向开关,所述光伏阵列的正极与防反二极管的正极连接；所述三个双向开关的另一端和三个桥臂的中点与LCL滤波部分连接。本发明对变换器功率级的三相桥臂各个开关和双向开关进行复用,将光伏阵列和储能电池分散分配到主功率电路中,方便对两者进行功率平衡。(The invention discloses a converter based on a three-port distributed photovoltaic energy storage hybrid structure. The invention adopts a single star topology structure, which comprises an energy storage medium part, a power level part and an LCL filtering part; the energy storage medium part comprises an energy storage battery and a photovoltaic array; the power stage part comprises a direct current side anti-reverse diode, a three-phase bridge arm structure consisting of a plurality of power switches and a bidirectional switch, and the anode of the photovoltaic array is connected with the anode of the anti-reverse diode; the other ends of the three bidirectional switches and the middle points of the three bridge arms are connected with the LCL filtering part. The invention multiplexes the switches and the bidirectional switches of the three-phase bridge arm of the power level of the converter, distributes the photovoltaic array and the energy storage battery to the main power circuit in a dispersed manner, and is convenient for power balance of the photovoltaic array and the energy storage battery.)
1. Converter based on three-port distributed photovoltaic energy storage hybrid structure adopts single star topology structure, its characterized in that: the device comprises an energy storage medium part, a power stage part and an LCL filtering part; the energy storage medium part comprises an energy storage battery and a photovoltaic array;
the power stage part comprises a direct current side anti-reverse diode, a three-phase bridge arm structure consisting of a plurality of power switches and a bidirectional switch, and the anode of the photovoltaic array is connected with the anode of the anti-reverse diode;
in a three-phase bridge arm configuration, the power switch IGBT Sc1And power switch IGBT Sc2Form a first arm, a power switch IGBT Sc3And power switch IGBT Sc4Forming a second arm, a power switch IGBT Sc5And power switch IGBT Sc6Forming a third bridge arm; power switch IGBT Sc1And IGBT Sc2The collector electrodes are connected; power switch IGBT Sc3And IGBT Sc4The collector electrodes are connected; power switch IGBT Sc5And IGBT Sc6The collector electrodes are connected;
power switch IGBTSc1、Sc3、Sc5The collector electrodes of the power switches are all connected with the cathode of the anti-reverse diode, and the power switch IGBT Sc1、Sc3、Sc5The emitting electrode of the power switch is connected with the positive electrode of the energy storage battery through three bidirectional switches, and the power switch IGBT Sc2、Sc4、Sc6The emitter of the photovoltaic array is connected with the negative electrode of the photovoltaic array and the negative electrode of the energy storage battery;
the other ends of the three bidirectional switches and the middle points of the three bridge arms are connected with the LCL filtering part.
2. The three-port distributed photovoltaic energy storage hybrid based converter according to claim 1, wherein: in the three-phase bridge arm structure, the power switch is a reverse conducting power switch.
3. The three-port distributed photovoltaic energy storage hybrid based converter according to claim 1, wherein: the LCL filtering part comprises a filtering inductor and a filtering capacitor connected with the filtering inductor.
4. As claimed in claim3 the converter based on three-port distributed photovoltaic energy storage hybrid structure is characterized in that: filter inductance L1-1、L1-2Series, filter inductance L1-1One end of (1), the midpoint of the first bridge arm and the first bidirectional switch SW1One end of the filter capacitor C is connected1And a filter inductor L1-1、L1-2Connecting; filter inductance L2-1、L2-2Series, filter inductance L2-1With one end of the first leg midpoint and the second bidirectional switch SW2One end of the filter capacitor C is connected2And a filter inductor L2-1、L2-2Connecting; filter inductance L3-1、L3-2Series, filter inductance L3-1One end of (1) and the first bridge arm midpoint and the third bidirectional switch SW3One end of the filter capacitor C is connected3And a filter inductor L3-1、L3-2Are connected.
5. The three-port distributed photovoltaic energy storage hybrid based converter according to claim 1, wherein: in a three-phase bridge arm configuration, the power switch IGBT Sc1Collector electrode, IGBT Sc3Collector and IGBT Sc5The collector electrodes are connected.
6. The three-port distributed photovoltaic energy storage hybrid based converter according to any of claims 1-5, wherein: the bidirectional switch is composed of a plurality of power switch tubes.
7. The three-port distributed photovoltaic energy storage hybrid based converter according to claim 6, wherein: the bidirectional switch is composed of two reverse conducting type power IGBTVT1And VT2Reverse series connection of IGBT VT1Emitter and VT2The emitter of (3) is connected; wherein one IGBT V in the first bidirectional switchT11The collector of the power storage battery is connected with the anode of the power storage battery, and the other IGBT VT12The collector of the bridge is connected with the midpoint of the first bridge arm; one IGBT V in the second bidirectional switchT21The collector of the energy storage battery is connected with the anode of the energy storage battery,the other IGBT VT22The collector of the second bridge arm is connected with the midpoint of the second bridge arm; one IGBT V in the third bidirectional switchT31The collector of the power storage battery is connected with the anode of the power storage battery, and the other IGBT V is connected with the anode of the power storage batteryT32Is connected with the midpoint of the third leg.
8. The three-port distributed photovoltaic energy storage hybrid based converter according to claim 6, wherein: the bidirectional switch is formed by reversely connecting two reverse resistance type power IGBTs in parallel, one end of the bidirectional switch is connected with the anode of the energy storage battery, and the other end of the bidirectional switch is connected with the midpoint of the bridge arm.
Technical Field
The invention belongs to the technical field of power electronic systems, and particularly relates to a converter based on a three-port distributed photovoltaic energy storage hybrid structure.
Background
The distributed photovoltaic power generation has the advantages of cleanness, environmental protection, flexible construction, nearby utilization, small influence of a single body on a power grid and the like, has important significance for optimizing an energy structure, promoting energy conservation and emission reduction and realizing economic sustainable development, and becomes one of important forms of solar energy utilization. However, the output of the distributed photovoltaic power generation has the defects of randomness, intermittence and the like, and after the distributed photovoltaic power generation is connected to a power grid, the power fluctuation, the electric energy quality reduction and other adverse effects of the power grid can be caused. In order to inhibit adverse effects on a power grid caused by access of distributed photovoltaic power generation and the like to the power grid, an energy storage link needs to be introduced.
The energy storage can charge as the load when the power consumption is low ebb, can discharge as the power when the power consumption is high peak, can effectively stabilize power fluctuation, load shifting, can also participate in the frequency pressure regulating and demand response of electric wire netting, realizes the large-scale high permeability of distributed power generation and inserts, can show the absorption level that improves the new forms of energy, supports distributed power generation and little electric wire netting, is the key technology that promotes fossil energy to renewable energy conversion.
The photovoltaic and energy storage combined power generation system is the best application form of combining photovoltaic and energy storage, and the photovoltaic and energy storage combined power generation device is the core of the photovoltaic and energy storage combined power generation system, can affect a plurality of factors such as conversion efficiency, electric energy quality and power grid adaptability of the system, and has the characteristics of modular design, low cost, convenience in maintenance, short development period and the like.
In the traditional rectification inverter circuit, a direct current side is a port, and the use of the traditional rectification inverter circuit is limited to a certain extent; particularly in the field of new energy such as distributed photovoltaic power generation, a direct-current side multi-port parallel access technology is needed.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a converter based on a three-port distributed photovoltaic energy storage hybrid structure, which utilizes a bidirectional switch to realize the cooperative work of a photovoltaic array and an energy storage battery in the converter, and distributes the photovoltaic array and the energy storage battery to a main power circuit in a dispersing way, so that the power balance of the photovoltaic array and the energy storage battery is conveniently carried out.
Therefore, the invention adopts the following technical scheme: the converter based on the three-port distributed photovoltaic energy storage hybrid structure adopts a single star topology structure and comprises an energy storage medium part, a power level part and an LCL (lower control limit) filtering part; the energy storage medium part comprises an energy storage battery and a photovoltaic array;
the power stage part comprises a direct current side anti-reverse diode, a three-phase bridge arm structure consisting of a plurality of power switches and a bidirectional switch, and the anode of the photovoltaic array is connected with the anode of the anti-reverse diode;
in a three-phase bridge arm configuration, the power switch IGBT Sc1And power switch IGBT Sc2Form a first arm, a power switch IGBT Sc3And power switch IGBT Sc4Forming a second arm, a power switch IGBT Sc5And power switch IGBT Sc6Forming a third bridge arm; power switch IGBT Sc1And IGBT Sc2The collector electrodes are connected; power switch IGBT Sc3And IGBT Sc4The collector electrodes are connected; power switch IGBT Sc5And IGBT Sc6The collector electrodes are connected;
power switch IGBTSc1、Sc3、Sc5The collector electrodes of the power switches are all connected with the cathode of the anti-reverse diode, and the power switch IGBT Sc1、Sc3、Sc5The emitting electrode of the power switch is connected with the positive electrode of the energy storage battery through three bidirectional switches, and the power switch IGBT Sc2、Sc4、Sc6And negative electrode of photovoltaic arrayIs connected with the negative electrode of the energy storage battery;
the other ends of the three bidirectional switches and the middle points of the three bridge arms are connected with the LCL filtering part.
The three-phase bridge arm adopts a common power device, and is convenient to purchase, install and manufacture.
Further, in the three-phase bridge arm structure, the power switch is a reverse conducting power switch. The reverse conducting power switch can be an insulated gate bipolar transistor.
Furthermore, the LCL filtering part comprises a filtering inductor and a filtering capacitor connected with the filtering inductor.
Further, a filter inductor L1-1、L1-2Series, filter inductance L1-1One end of (1), the midpoint of the first bridge arm and the first bidirectional switch SW1One end of the filter capacitor C is connected1And a filter inductor L1-1、L1-2Connecting; filter inductance L2-1、L2-2Series, filter inductance L2-1With one end of the first leg midpoint and the second bidirectional switch SW2One end of the filter capacitor C is connected2And a filter inductor L2-1、L2-2Connecting; filter inductance L3-1、L3-2Series, filter inductance L3-1One end of (1) and the first bridge arm midpoint and the third bidirectional switch SW3One end of the filter capacitor C is connected3And a filter inductor L3-1、L3-2Are connected. The output end of the LCL filtering part is directly connected to the three-phase power grid voltage to play a role in filtering.
Further, in a three-phase bridge arm structure, the power switch IGBT Sc1Collector electrode, IGBT Sc3Collector and IGBT Sc5The collector electrodes are connected.
Furthermore, the bidirectional switch is composed of a plurality of power switch tubes.
Furthermore, the bidirectional switch is composed of two reverse conducting power IGBTVT1And VT2Reverse series connection of IGBT VT1Emitter and VT2The emitter of (3) is connected; wherein one IGBT V in the first bidirectional switchT11The collector of the power storage battery is connected with the anode of the power storage battery, and the other IGBT VT12The collector of the bridge is connected with the midpoint of the first bridge arm; one IGBT V in the second bidirectional switchT21The collector of the power storage battery is connected with the anode of the power storage battery, and the other IGBT V is connected with the anode of the power storage batteryT22The collector of the second bridge arm is connected with the midpoint of the second bridge arm; one IGBT V in the third bidirectional switchT31The collector of the power storage battery is connected with the anode of the power storage battery, and the other IGBT V is connected with the anode of the power storage batteryT32Is connected with the midpoint of the third leg.
Furthermore, the bidirectional switch is formed by reversely connecting two reverse resistance type power IGBTs in parallel, one end of the bidirectional switch is connected with the anode of the energy storage battery, and the other end of the bidirectional switch is connected with the midpoint of the bridge arm.
According to the requirement, a plurality of photovoltaic cell panels can be connected in series or in parallel to form a photovoltaic array to replace a single photovoltaic cell panel; after a plurality of energy storage batteries are connected in series or in parallel, a single battery is replaced. The photovoltaic array can be any type of photovoltaic array; the energy storage battery can be any type of energy storage battery.
The ordinary IGBT has reverse blocking capability, and an anti-parallel freewheeling diode is usually adopted to form a reverse conducting switch. The IGBT used in the present invention is a reverse conducting IGBT having an antiparallel diode.
The invention has the following effects: the photovoltaic array and the energy storage battery are distributed to the main power circuit in a dispersing way, so that power balance between the photovoltaic array and the energy storage battery is facilitated.
Drawings
FIG. 1 is a schematic diagram of a bi-directional switch of the present invention;
FIG. 2 is a schematic diagram of another bi-directional switch configuration of the present invention;
fig. 3 is a schematic structural diagram of a converter based on a three-port distributed photovoltaic energy storage hybrid structure.
Detailed Description
In order to facilitate those skilled in the art to better understand and implement the present invention, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and the specific embodiments, but the present invention is not limited to the embodiments.
The converter based on the three-port distributed photovoltaic energy storage hybrid structure adopts a single star topology structure and comprises an energy storage medium part, a power level part and an LCL (lower control limit) filtering part; the energy storage medium part comprises an energy storage Battery and a photovoltaic array PV. The entire converter passes through a filter circuit (i.e., an LCL filter section) and is on a three-phase power grid.
The power stage part comprises a direct current side anti-reverse diode D0The photovoltaic array comprises a three-phase bridge arm structure consisting of a plurality of power switches and a bidirectional switch, wherein the positive electrode of the photovoltaic array is connected with the positive electrode of an anti-reverse diode.
In a three-phase bridge arm configuration, the power switch IGBT Sc1And power switch IGBT Sc2Form a first arm, a power switch IGBT Sc3And power switch IGBT Sc4Forming a second arm, a power switch IGBT Sc5And power switch IGBT Sc6Forming a third bridge arm; power switch IGBT Sc1And IGBT Sc2The collector electrodes are connected; power switch IGBT Sc3And IGBT Sc4The collector electrodes are connected; power switch IGBT Sc5And IGBT Sc6Is connected to the collector of the collector. Power switch IGBT Sc1Collector electrode, IGBT Sc3Collector and IGBT Sc5The collector electrodes are connected.
Power switch IGBTSc1、Sc3、Sc5The collector electrodes of the power switches are all connected with the cathode of the anti-reverse diode, and the power switch IGBT Sc1、Sc3、Sc5The emitting electrode of the power switch is connected with the positive electrode of the energy storage battery through three bidirectional switches, and the power switch IGBT Sc2、Sc4、Sc6Is connected with the negative electrode of the photovoltaic array and the negative electrode of the energy storage battery.
The three bidirectional switches SW1、SW2、SW3The other end of the three bridge arms and the middle points of the three bridge arms are connected with the LCL filtering part.
The LCL filtering part comprises a filtering inductor and a filtering capacitor connected with the filtering inductor. Filter inductance L1-1、L1-2Series, filter inductance L1-1One end of (1), the midpoint of the first bridge arm and the first bidirectional switch SW1One end of the filter capacitor C is connected1And a filter inductor L1-1、L1-2Connecting; filter inductance L2-1、L2-2Series, filter inductance L2-1With one end of the first leg midpoint and the second bidirectional switch SW2One end of the filter capacitor C is connected2And a filter inductor L2-1、L2-2Connecting; filter inductance L3-1、L3-2Series, filter inductance L3-1One end of (1) and the first bridge arm midpoint and the third bidirectional switch SW3One end of the filter capacitor C is connected3And a filter inductor L3-1、L3-2Are connected.
The modulation mode of the converter based on the three-port distributed photovoltaic energy storage hybrid structure can adopt an SPWM (sinusoidal pulse width modulation) or SVPWM (space vector pulse width modulation) modulation mode, and two media on the direct current side are utilized in a time-sharing mode.
The bidirectional switch of the present invention can adopt two structures:
the first type of bi-directional switch is shown in fig. 1 and consists of two reverse conducting power IGBTs connected in series in reverse, where IGBT VT1Emitter and VT2Is connected to the emitter. A first bidirectional switch SW1Medium, IGBTVT11The collector of the capacitor is connected with the positive electrode of a super capacitor, IGBTVT12The collector of the bridge is connected with the midpoint of the first bridge arm; second bidirectional switch SW2Medium, IGBTVT21The collector of the capacitor is connected with the positive electrode of a super capacitor, IGBTVT22The collector of the second bridge arm is connected with the midpoint of the second bridge arm; third bidirectional switch SW3Medium, IGBTVT31The collector of the capacitor is connected with the positive electrode of a super capacitor, IGBTVT32Is connected with the midpoint of the third leg. By controlling the two power IGBTs, a bidirectional flow of energy can be achieved, fromAnd controls the power throughput between the energy storage battery and the power grid.
As shown in fig. 3, when the bidirectional switch is the first type of bidirectional switch.
Working mode 1: SW1、SW2、SW3When the power switches on the other bridge arms are switched off for a long time and have switching actions, the photovoltaic array is charged to a power grid at the moment.
The working mode 2 is as follows: when all the power switches have switching actions, the photovoltaic array supplies energy to the power grid and charges the energy storage battery at the same time.
Working mode 3: three power switches S of middle and upper bridge arms in all bridge armsC1、SC3、SC5When the power supply is turned off for a long time and other power switches have switching actions, the energy storage battery supplies power to the power grid.
The working mode 4 is as follows: the voltage and the current of the power grid are in reverse phases, and when all the power switches have switching actions, the power grid charges the energy storage battery.
When all IGBTs are off, the converter is considered to be blocked.
The converter will only be in one of the above four operating states at any time.
The second bidirectional switch is shown in fig. 2, and is formed by connecting two reverse-resistance power IGBTs in anti-parallel. VT1Emitter and VT2Is connected to the collector of VT1Collector electrode of and VT2Are connected. One end of the IGBT is connected with the anode of the super capacitor, and the other end of the IGBT is connected with the midpoint of each bridge arm. SW1In, VT11Emitter and VT12Is connected to the positive pole of the super capacitor, VT11Collector electrode of and VT12Is connected to the midpoint of the first leg; SW2In, VT21Emitter and VT22Is connected to the positive pole of the super capacitor, VT21Collector electrode of and VT22Is connected to the midpoint of the first leg; SW3In, VT31Emitter and VT32Is connected to the positive pole of the super capacitor, VT31Collector electrode of and VT32Is connected to the midpoint of the first leg.
As shown in fig. 3, when the bidirectional switch is the second type of switch, it is for the entire converter.
Working mode 1: SW1、SW2、SW3When the power switches on the rest bridge arms are switched off for a long time and are switched on, the photovoltaic array is charged to a power grid.
The working mode 2 is as follows: when all the power switches have switching actions, the photovoltaic array supplies energy to the power grid and charges the energy storage battery at the same time.
Working mode 3: three power switches S of middle and upper bridge arms in all bridge armsC1、SC3、SC5When the power supply is turned off for a long time and other power switches have switching actions, the energy storage battery supplies power to the power grid.
The working mode 4 is as follows: the voltage and the current of the power grid are in reverse phases, and when all the power switches have switching actions, the power grid charges the energy storage battery.
When all IGBTs are off, the converter is considered to be blocked.
The converter will only be in one of the above four operating states at any time.
Through a pulse modulation mode, a three-phase bridge arm and a bidirectional switch in the converter can be flexibly controlled, the energy flow between the converter and a power grid is controlled, the energy of the converter is redistributed, the input and output power of a system can be controlled, and the energy flow direction is controlled.
Reactive power and active power of a power grid input system are controlled through input current of a control system, and energy storage and low-frequency reactive power compensation are performed by using a battery.
The photovoltaic array and energy storage battery combined power generation system has a simple circuit structure, realizes the cooperative work of the photovoltaic array and the energy storage battery in the converter by utilizing the bidirectional switch, and has the advantages of small impact on a power grid, scheduling capability, good quality of grid-connected electric energy, capability of providing inertia and damping for the system and the like.
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