阅读说明：本技术 一种高压大容量svg测试电源 (High-voltage large-capacity SVG test power supply ) 是由 陆道荣 沙辰星 胡海兵 于 2019-10-12 设计创作，主要内容包括：本发明的目的是提供一种高压大容量SVG测试电源,在电网容量较小难以实现大容量无功补偿设备满载运行的情况下,本发明将为各厂家的高压装置提供良好的测试环境。实现本发明需要的设备主要包括：380V的低压交流电源、升压变压器、陪试SVG设备1、陪试SVG设备2和被试大容量SVG设备。在被试大容量SVG设备的直流侧母线电压稳定后,在陪试SVG设备2调制波注入各种类型的分量,为被试大容量SVG设备创造不同的工作条件。本发明不但可以实现大容量SVG设备的满载运行,还能够在不增加其他负载、不改变现有接线的情况下模拟多种类型的电网工况,功能全面。(The invention aims to provide a high-voltage large-capacity SVG test power supply, which can provide a good test environment for high-voltage devices of various manufacturers under the condition that the full-load operation of large-capacity reactive compensation equipment is difficult to realize due to small power grid capacity. The equipment for realizing the invention mainly comprises: 380V low-voltage alternating-current power supply, a step-up transformer, an accompanying SVG device 1, an accompanying SVG device 2 and a tested large-capacity SVG device. After the direct current side bus voltage of the tested large-capacity SVG device is stable, various types of components are injected into the modulation wave of the accompanying test SVG device 2, and different working conditions are created for the tested large-capacity SVG device. The invention not only can realize the full-load operation of the large-capacity SVG equipment, but also can simulate various power grid working conditions without increasing other loads and changing the existing wiring, and has comprehensive functions.)

1. A high-voltage large-capacity SVG testing power supply mainly comprises: 380V's low pressure alternating current power supply, step-up transformer, accompany examination SVG equipment 1, accompany examination SVG equipment 2 and by examination large capacity SVG equipment, its characterized in that: the primary side of the step-up transformer is connected with a 380V low-voltage alternating-current power supply, the secondary side of the step-up transformer is connected with an alternating-current output end of the accompanying and testing SVG device 1, a direct-current side of each power module of the accompanying and testing SVG device 2 is connected with a direct-current side of each power module of the accompanying and testing SVG device 1 in parallel, and an alternating-current output end of the accompanying and testing SVG device 2 is connected with an alternating-current output end of the tested high-capacity SVG device through an output reactor; when the capacity of the tested large-capacity SVG equipment is improved, the accompanying SVG equipment 1 and the accompanying SVG equipment 2 can be flexibly selected in series products of the same specification, and the low-voltage alternating-current power supply and the step-up transformer do not need to be adjusted.

2. The high-voltage high-capacity SVG test power supply of claim 1, wherein: the secondary side of the booster transformer comprises two taps, so that 380V alternating current voltage connected to the primary side can be boosted to 10kV or 35 kV; the capacity of step-up transformer is less than by examination SVG equipment far away, only needs to be greater than two and accompanies the sum of the active power of examination SVG equipment and by examination large capacity SVG equipment, about 1% of reactive capacity for the direct current side voltage stability that maintains SVG equipment.

3. The high-voltage high-capacity SVG test power supply of claim 1, wherein: the voltage class of accompanying and trying on SVG equipment 1 is the same with the large capacity SVG of being tried, but the capacity is less than by the SVG equipment of trying on far away to work in active rectification mode, provide stable direct current bus voltage for accompanying and trying on SVG equipment 2.

4. The high-voltage high-capacity SVG test power supply of claim 1, wherein: the accompanying test SVG device 2 has the same specification as the tested large-capacity SVG device, works in an inversion mode, and stably controls the output voltage of the AC side to be the same as the voltage grade of the secondary side of the step-up transformer; the voltage of the direct current side of the accompanying and testing SVG device 2 is controlled and stabilized by the accompanying and testing SVG device 1, and components in different forms, including harmonic components, unbalanced components and mutation components, are injected into the modulation wave to simulate common power grid accidents.

5. The high-voltage high-capacity SVG test power supply of claim 4, characterized in that: the common grid accidents include flicker, voltage sag, voltage imbalance, voltage harmonics, etc.

6. The high-voltage high-capacity SVG test power supply of claim 1, wherein: accompanying and trying on SVG equipment 1, accompanying and trying on SVG equipment 2 and by the high capacity SVG equipment of examination for cascade H bridge topology, and three equipment possess the power module and the voltage class of the same quantity.

Technical Field

The invention relates to the technical field of power electronic reactive power compensation, in particular to a high-voltage large-capacity SVG test power supply.

Background

With the continuous development of national economy, the requirements of industrial and agricultural production and life on the quality and reliability of electric energy are higher and higher, so that various large-capacity reactive compensation equipment is produced. Manufacturers producing the devices can not use commercial power if the manufacturers need to perform the tests with the voltage of more than 400V when the functional tests of the devices are performed, and need to apply for records to relevant departments to build a simulation test field and perform simulation live-line tests, but the application program is troublesome, and the construction cost of the test field is high.

At present, the common full-load test of the large-capacity reactive compensation equipment is realized by carrying out mutual pushing with equipment with larger capacity, so that the network access current is small enough and does not exceed the capacity of a power grid, and a company just starting does not have the condition of having equipment with larger capacity, so that the high-voltage large-capacity SVG test power supply is very important.

Synchronous generators, synchronous motors, electrostatic capacitors and other devices are the most common reactive power generation sources in the system, but reactive power generated by the devices affects the power grid, so that the quality of the power grid is poor, and the capacity is difficult to adjust, so that a controllable reactive power source needs to be realized by power electronic equipment. The existing reactive power source scheme is to adjust the voltage of a power grid through a high-voltage variable-frequency power source or a matrix converter, the cost is high, and for reactive compensation equipment, only reactive exchange is needed in full-load operation, so that too much active power cannot be consumed, and therefore, a reactive power source is not needed to bear too much active power. In addition, the traditional test scheme needs a transformer with a larger volume, has large loss and high cost, greatly limits the test capacity, and is not applicable any more and poor in flexibility when the capacity grade of a product of a manufacturer is further improved.

Disclosure of Invention

The purpose of the invention is as follows:

the invention aims to provide a high-voltage large-capacity SVG test power supply, which can provide a good test environment for high-voltage devices of various manufacturers under the condition that the full-load operation of large-capacity reactive compensation equipment is difficult to realize due to small power grid capacity.

The technical scheme is as follows:

the invention adopts the following technical scheme for realizing the aim of the invention:

1) the primary side of the booster transformer is connected with a low-voltage alternating-current power supply, the secondary side of the booster transformer is connected with the alternating-current side of the existing small-capacity reactive compensation equipment, and the primary side voltage of 380V is boosted to 10kV/35 kV;

2) the accompanying SVG device 1 is used as a rectifier, the output end of the alternating current side is connected with the secondary side of the step-up transformer according to the phase sequence, and the direct current side provides stable direct current side bus voltage for the accompanying SVG device 2;

3) the AC side of the accompanying test SVG device 2 is connected with the AC side of the tested large-capacity SVG device through an output reactor;

4) firstly, rectifying the secondary side alternating-current voltage of a boosting transformer by an accompanying SVG device 1 to obtain a stable direct-current side bus voltage, and using the voltage as the direct-current side bus voltage of the accompanying SVG device 1;

5) then, the test-assisting SVG device 2 is used as an inverter, the AC side provides the same AC voltage as the secondary side of the step-up transformer to the tested large-capacity SVG device, and the tested large-capacity SVG device is used as a rectifier to raise the DC side bus voltage of the tested large-capacity SVG device to the rated working voltage level;

6) finally, after the voltage of a direct-current side bus of the tested high-capacity SVG device is stabilized, the positive sequence and negative sequence current instructions of the tested high-capacity SVG device 2 are modified, different working conditions are created for the tested high-capacity SVG device, and functional tests such as full-load operation, low-voltage ride-through, high-voltage ride-through, harmonic compensation and the like are realized;

the required equipment for realizing the analog source mainly comprises: 380V low-voltage alternating-current power supply, a step-up transformer, an accompanying and testing SVG device 1, an accompanying and testing SVG device 2 and a tested large-capacity SVG device.

The secondary side of the boosting transformer comprises two taps, a 380V low-voltage alternating-current power supply can be boosted to 10kV or 35kV, and meanwhile, the boosting transformer only bears active loss generated by testing of testing equipment and is far smaller than the reactive capacity of tested high-capacity SVG equipment;

the topology adopted by the accompanying test SVG device 1 is a cascade H-bridge topology, and the operation capacity is far smaller than that of the tested high-capacity SVG device;

the accompanying-testing SVG device 2 adopts products with the same specification as the tested high-capacity SVG device, adopts a cascaded H-bridge topology, and has the same operation capacity;

the number of each phase of power modules of the accompanying test SVG device 1, the accompanying test SVG device 2 and the tested large-capacity SVG device is the same, and the voltage levels are also the same;

the accompanying and testing SVG device 1 is used as an active rectifier, absorbs active power from a power grid to regulate direct-current side voltage, and provides balanced and stable direct-current side voltage for the accompanying and testing SVG device 2;

the voltage of the direct current side of the accompanying SVG device 2 is controlled by the accompanying SVG device 1 to be equalized, and different types of power grid voltage faults can be realized only by injecting different types of components into the modulation wave; injecting harmonic components, and enabling the accompanying test SVG device 2 to simulate the harmonic voltage condition; injecting different fundamental frequency components into the three-phase modulation wave, and simulating the unbalanced condition of the power grid voltage by the accompanying test SVG device 2; abrupt components are injected into the three-phase modulation wave, and the accompanying test SVG device 2 can simulate the faults of grid voltage drop, sudden rise or flicker and the like;

compared with the prior art, the invention has the following obvious advantages:

1. the capacity of the power grid and the capacity of the booster transformer are both very low, and only the very low active power generated by the running of the SVG equipment is needed to be born by the booster transformer, which is about 1 percent of the reactive capacity, so the cost is low;

2. the invention can simulate two voltage grades of 10kV and 35kV only by using mains supply with a 380V factory building voltage grade, and has strong applicability;

3. when the product capacity is upgraded, only the auxiliary SVG equipment is selected from the existing products of the same series, and the booster transformer and the low-voltage alternating-current power supply do not need to be changed, so that the flexibility is high;

4. the invention not only can realize the full-load operation of the large-capacity SVG equipment, but also can simulate various power grid working conditions under the conditions of not increasing other loads and not changing the existing wiring, and has comprehensive functions;

in conclusion, the high-voltage large-capacity SVG testing power supply provided by the invention has the advantages of low cost, simplicity in operation and the like, and can be used for facilitating manufacturers who do not have high-voltage large-capacity power grid conditions and still performing full-load experiments on large-capacity reactive compensation equipment and function tests under different power grid working conditions, so that large-scale production is realized.

Drawings

FIG. 1 is a schematic diagram of a high-voltage large-capacity SVG test power supply;

FIG. 2 is a main circuit structure of a cascaded H-bridge topology uniformly adopted by a companion test SVG device and a tested SVG device;

fig. 3 shows an a-phase direct-current side connection mode of the accompanying SVG device 1 and the accompanying SVG device 2, and the connection method of the remaining B, C two phases is the same as the connection method;

fig. 4 is a control block diagram of the auxiliary SVG device 2 in an active rectification mode;

fig. 5 is a control schematic diagram of the accompanying test SVG device 1 when a grid voltage fault is produced;

FIG. 6 shows three-phase balanced voltage and three-phase unbalanced voltage waveforms output by the high-voltage large-capacity SVG testing power supply;

in the figure, e_si(i ═ a, b, c) is a physical connection point O₁Grid voltage u as central point_iFor the output voltage, i, of the device with the physical connection point N as the central point_iIs a device current, R_sFor line impedance (including device loss equivalent resistance), QS represents a switch, KM is an AC contactor, R_chIs a pre-charge resistor, L is an AC side filter inductor, R_dcFor the module DC side discharge resistor, u_dcij(j ═ 1,2, …, n) represents the dc-side capacitance voltage of each module, u_dci(i ═ a, b, c) represents the sum of the dc-side voltages of the cells of one link (phase), simply called the phase dc-side voltage, and Cell k (k ═ 1,2, …, N) has the same structure as Cell 1; u. of_{dc_all}And u_{dc_ref}Respectively a sampling value and a reference value of the total voltage at the direct current side; i.e. i_dAnd i_qThe components of the device current on the d axis and the q axis after the device current is subjected to PARK conversion; i.e. i_{d_ref}Is a current loop d-axis component reference value; PI is a proportional integral regulator; d_a,d_b,d_cFor accompanying trialA modulated wave of the SVG device 1; m is_a,m_b,m_cAn initial modulation wave for the accompanying test SVG device 2; m_a,M_b,M_cTo try the final modulated wave of the SVG device 2.

Detailed Description

The invention provides a high-voltage high-capacity SVG test power supply, which is characterized in that firstly, a 380V low-voltage alternating current power supply is lifted to 10kV/35kV through a step-up transformer; then, the accompanying SVG device 1 undertakes the work of a rectifier, rectifies the alternating current on the secondary side of the step-up transformer into a stable direct current side bus voltage, and the bus voltage serves as the direct current side bus voltage of the accompanying SVG device 2; then, the auxiliary test SVG device 2 serves as an inverter to provide the tested SVG device with the same voltage level as the secondary side of the boosting transformer, and meanwhile, the tested SVG device serves as a rectifier to rectify the alternating voltage into a stable direct-current side bus voltage of the tested SVG device; and finally, after the direct-current side bus voltages of the accompanying and testing SVG equipment 2 and the tested SVG equipment are stable, injecting components of different types into three-phase modulation waves of the accompanying and testing SVG equipment 2, and enabling the accompanying and testing SVG equipment 2 to simulate power grid working conditions of different types, including flicker, harmonic voltage, three-phase voltage imbalance and the like.

The present invention will now be further described with reference to the particular drawings, which are provided for purposes of illustration and not limitation. Based on the embodiments of the present invention, those skilled in the art can obtain all other embodiments without providing creative efforts, and all embodiments are within the protection scope of the present invention. It should be noted that for ease of description, the drawings show only some, but not all, of the material relevant to the present invention.

The wiring of the high-voltage large-capacity SVG testing power supply provided by the invention is shown in figure 1, the primary side of a boosting transformer is connected with a 380V low-voltage alternating-current power supply, the secondary side of the boosting transformer is connected with the alternating-current side of an accompanying and testing SVG device 1, the accompanying and testing SVG device 1 and an accompanying and testing SVG device 2 share a direct-current side bus, and the alternating-current sides of the accompanying and testing SVG device 2 and the tested SVG device are sequentially connected according to a phase sequence.

The topological structures of the accompanying and tested SVG devices and the tested SVG devices both adopt a cascaded H-bridge structure with the same power module number, see FIG. 2, and it is noted that the voltage levels of the accompanying and tested SVG devices and the tested SVG devices are the same, and the reactive compensation capacities of the accompanying and tested SVG devices 2 and the tested SVG devices are also the same, so that the condition of full-load operation of the tested SVG devices can be met;

the phase A connection line of the accompanying SVG device 2 and the accompanying SVG device 1 is shown in FIG. 3, and the direct current sides of the power modules of the two devices are correspondingly connected;

referring to fig. 4, the accompanying SVG device 1 converts three-phase power grid current into a rotating coordinate system through PARK transformation, so that the alternating current quantity is changed into direct current quantity for convenient control, and meanwhile, the d-axis current component is responsible for adjusting the active component injected into the accompanying SVG device 1 by the power grid, controlling the voltage balance of the direct current side, and providing stable direct current side voltage for the accompanying SVG device 2;

referring to fig. 5, the accompanying SVG device 2 injects various types of components into the modulated wave to implement different types of grid voltage faults;

examples of the invention

The specific steps for realizing the high-voltage high-capacity SVG testing power supply are as follows:

step 1, the high-voltage large-capacity SVG test power supply provided by the invention is connected to commercial power, the capacity of the adopted auxiliary test SVG equipment 1 is 1MVA, a star-shaped cascade H-bridge topology is adopted, and each phase contains 12 modules; the capacities of the accompanying SVG device 2 and the tested SVG device are both 10MVA, the adopted topology is the same as that of the existing small-capacity device, and finally the tested SVG device is connected into the high-voltage large-capacity SVG test power supply according to the figure 2;

step 2, setting the accompanying SVG device 1 as a rectification stage, rectifying 10kV alternating current voltage into 10kV direct current side bus voltage, wherein the direct current side voltage of each module reaches 850V, namely the normal working condition;

step 3, the accompanying SVG device 2 judges whether the voltage of the direct current side bus reaches a normal working condition, if the voltage of the direct current side bus reaches 10kV and the voltages of all modules are balanced, the accompanying SVG device 2 enters an inversion stage to convert the voltage of the 10kV direct current side bus into 10kV alternating current voltage, otherwise, the accompanying SVG device 2 is in a standby state;

step 4, the tested SVG equipment judges whether the AC side voltage reaches 10kV, if so, the tested SVG equipment enters a rectification stage to rectify the 10kV AC voltage into 10kV DC side bus voltage, otherwise, the tested SVG equipment is in a standby state;

step 5, after the direct-current side bus voltages of the accompanying SVG device 2 and the tested SVG device reach 10kV and the direct-current side voltages of the modules are balanced, the tested SVG device tracks and compensates the small reactive power emitted by the accompanying SVG device 2, so that the reactive power emitted by the two devices is the same in magnitude and opposite in polarity, and otherwise, the two devices continue to wait for normal working conditions;

step 6, after the small reactive power sent by the accompanying and testing SVG device 2 is completely compensated by the tested SVG device, gradually raising the reactive power sent by the accompanying and testing SVG device 2 until the full load power is reached;

and 7, reducing the reactive power sent by the accompanying SVG equipment 2, injecting unbalanced components into the three-phase modulation wave of the accompanying SVG equipment 2 to enable the output voltage to be unbalanced voltage, referring to fig. 6, and continuously performing reactive power compensation by the tested SVG equipment.