A dynamic voltage restorer whole machine performance testing system and method

Abstract

The present invention discloses a dynamic voltage restorer whole machine performance test system and method belonging to the technical field of transient power quality index management. The test power supply, series branch, dynamic voltage restorer and controllable reactor branch of the system are connected in series in sequence, the controllable reactor branch is connected in parallel with the parallel resistor branch, and the filter compensation branch is connected in parallel with the dynamic voltage restorer on the input side of the dynamic voltage restorer; the three-phase contactless solid-state switch T1 is connected to the test power supply, and the three-phase series reactor L0 is connected to the input side of the dynamic voltage restorer; the filter compensation branch is composed of a three-phase filter capacitor and a three-phase filter reactor in series, and the three-phase filter reactor is connected to the neutral line in star shape; the thyristor valve group T2 is connected to the output side of the dynamic voltage restorer, and the three-phase parallel reactor L4 is connected to the neutral line in star shape. The system and method avoid interference to the test power supply network caused by the access of the test loop, and reduce the test power supply capacity demand.

Description

Technical Field

[0001] The present invention relates to the technical field of transient power quality index management, and in particular to a dynamic voltage restorer whole machine performance testing system and method. Background Art

[0002] Voltage sags, swells and interruptions are common phenomena in power grid operation, and they cannot be avoided no matter how the power supply reliability is improved. According to the importance of sensitive equipment, installing dynamic voltage restorers (DVRs) at different locations and nodes is an effective measure to deal with the above power quality problems. The DVR device combines power electronics technology with advanced supercapacitor energy storage technology. When the system experiences voltage sags, swells or short-term interruptions, the DVR device can use the electric energy stored in the supercapacitor to provide it to the load through the inverter and transformer circuit, so that the user's critical loads can maintain normal power supply during the abnormal grid voltage period and protect the normal operation of the load.

[0003] As the capacity of DVR devices increases and their functions become more complex, the requirements for DVR device performance testing technology, test device capacity and functions are also increasing. Conventional test circuits verify the DVR compensation effect by disconnecting the 380V power supply. They can only simulate voltage interruption, but cannot simulate voltage sag and swell. The performance assessment of DVR is not comprehensive, and the power supply capacity is small, which cannot meet the requirements of full-power testing of thyristors and IGBT power devices in DVR. Most domestic manufacturers' DVR products are shipped directly without full-power performance testing. After the device is connected to the system, it will be on standby for a long time and will only work for a short time when the voltage is temporarily reduced. The fault of the DVR device itself is not easy to detect, and the DVR equipment cannot play the expected effect when the voltage is temporarily reduced. In order to meet the growing demand for test technology, it is inevitable to continuously introduce new test methods, new test devices and new test circuit parameters. It is very important to develop a system suitable for dynamic voltage restorer (DVR) performance testing, which is used for DVR product development or factory testing, to verify the functions of DVR devices, ensure the accuracy of device function parameters, and consider the full-cycle full-power of power devices, so as to meet the requirements of large-capacity DVR test technology development. Summary of the invention

[0004] The purpose of the present invention is to provide a dynamic voltage restorer whole machine performance testing system and method.

[0005] A dynamic voltage restorer whole machine performance test system, characterized in that the system comprises a test power supply, a series branch, a filter compensation branch, a dynamic voltage restorer, a controllable reactor branch and a parallel resistor branch; wherein the test power supply, the series branch, the dynamic voltage restorer and the controllable reactor branch are sequentially connected in series, the controllable reactor branch is connected in parallel with the parallel resistor branch, and the filter compensation branch is connected in parallel with the dynamic voltage restorer at the input side of the dynamic voltage restorer;

[0006] The series branch is composed of a three-phase contactless solid-state switch T1 and a three-phase series reactor L0 connected in series, wherein the three-phase contactless solid-state switch T1 is connected to the test power supply, and the three-phase series reactor L0 is connected to the input side of the dynamic voltage restorer;

[0007] The filter compensation branch is composed of a three-phase filter capacitor and a three-phase filter reactor connected in series, and the three-phase filter reactor is connected to the neutral line in star shape;

[0008] The dynamic voltage restorer comprises a bypass thyristor, a voltage source converter and an energy storage device, wherein the bypass thyristor is arranged between corresponding phases of the input side and the output side of the dynamic voltage restorer, the voltage source converter is connected in parallel to the output side of the dynamic voltage restorer, and the energy storage device is installed on the DC side of the voltage source converter;

[0009] The controllable reactor branch is composed of a thyristor valve group T2 and a three-phase shunt reactor L4 connected in series, wherein the thyristor valve group T2 is connected to the output side of the dynamic voltage restorer, and the three-phase shunt reactor L4 is connected to the neutral line in a star shape;

[0010] The parallel resistor branch is composed of a phase-splitting contactor K and a parallel resistor R connected in series, wherein the phase-splitting contactor K is connected to the output side of the dynamic voltage restorer, and the parallel resistor R is connected to the neutral line in a star shape.

[0011] The filtering and compensating branches are provided in one group or in multiple groups in parallel as required.

[0012] The three-phase contactless solid-state switch T1 conducts one phase, two phases or three phases as required.

[0013] The energy storage device is a super capacitor or a lithium iron phosphate battery.

[0014] The thyristor valve group T2 includes 6 thyristors, 2 thyristors are anti-parallel connected in each phase and the trigger angle range of each thyristor is 90° to 180°.

[0015] The three-phase capacity of the controllable reactor branch is independently adjusted, and the capacity of each phase is continuously and smoothly outputted with an output range of 0-100%.

[0016] A test method for a dynamic voltage restorer whole machine performance test system, characterized in that the test method of the system includes a dynamic voltage restorer charging test method, a voltage interruption test method, a voltage swell test method and a voltage sag test method; the dynamic voltage restorer charging test method is specifically as follows:

[0017] The three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the test power supply is added to the input side of the dynamic voltage restorer through the three-phase series reactor L0, and the filter compensation branch and the controllable reactor branch are put into operation; the unbalanced resistive load is simulated by turning on and off each phase of the phase-splitting contactor K; the triggering angle of the thyristor valve group T2 of the controllable reactor branch is adjusted to keep the input side voltage of the dynamic voltage restorer stable; the filter compensation branch remains in the input state unchanged, absorbs the harmonic current generated by the controllable reactor branch, and generates a fixed capacitive reactive power at the same time, cooperating with the controllable reactor branch to stabilize the input side voltage of the dynamic voltage restorer.

[0018] The voltage interruption test method is as follows:

[0019] After the dynamic voltage restorer is charged, the trigger signal of one phase, two phases or three phases in the three-phase contactless solid-state switch T1 of the series branch is stopped, forming a voltage interruption; then the trigger signal of the three-phase contactless solid-state switch T1 is restored, and then the triggering is stopped again, forming a continuous voltage interruption to simulate the reclosing failure condition.

[0020] The voltage swell test method is as follows:

[0021] The dynamic voltage restorer is charged, all filter compensation branches are put into operation, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the thyristor valve group T2 of the controllable reactor branch is in the 90-degree trigger mode, and at least one phase of the parallel resistor branch is put into operation; in the initial stage of voltage swell, the one-phase, two-phase or three-phase trigger angle of the thyristor valve group T2 of the controllable reactor branch is quickly shifted from 90 degrees to the target angle to verify whether the dynamic voltage restorer can respond correctly.

[0022] The voltage sag test method is as follows:

[0023] After the dynamic voltage restorer is charged, one or two groups of filter compensation branches are withdrawn, and at least one group of filter compensation branches is withdrawn. The three-phase contactless solid-state switch T1 of the series branch is continuously turned on, and the triggering angle of the thyristor valve group T2 of the controllable reactor branch is changed to make the current input side voltage of the dynamic voltage restorer maintained at the voltage of the test power supply, and at least one phase of the parallel resistor branch is put into operation; in the initial stage of voltage sag, the one-phase, two-phase or three-phase triggering angle of the thyristor valve group T2 is quickly shifted from the current triggering mode to the target angle to verify whether the dynamic voltage restorer can respond correctly.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention can simulate various types of grid faults such as voltage interruption, temporary sag, temporary rise, etc., and conduct a comprehensive test on the switching function of the DVR device;

[0026] 2. The present invention can simulate different load types such as resistive, inductive, and resistive-inductive loads. It can simulate three-phase asymmetric loads through phase switching and conduct a comprehensive test on the load characteristics of the DVR device.

[0027] 3. The present invention only needs a small power capacity to complete the full-power test of the DVR, and can perform full-power and full-cycle tests on the bypass thyristor, IGBT converter and other power electronic devices inside the DVR to fully understand their electrical and temperature rise characteristics;

[0028] 4. The present invention adopts a voltage stable operation strategy to avoid interference to the test power supply network caused by the access of the test loop, thereby reducing the test power supply capacity requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A wiring diagram of a dynamic voltage restorer whole machine performance test system of the present invention;

[0030] Figure 2 The three-phase voltage short-time interruption waveform generated by the test system of the present invention;

[0031] Figure 3 It is a two-phase voltage short-time interruption waveform generated by the test system of the present invention;

[0032] Figure 4 The single-phase voltage short-time interruption waveform generated by the test system of the present invention;

[0033] Figure 5 The single-phase voltage short-time interruption waveforms generated by the test system of the present invention for two consecutive occurrences;

[0034] Figure 6 The three-phase voltage temporary rise waveform generated by the test system of the present invention;

[0035] Figure 7 The two-phase voltage transient rise waveform generated by the test system of the present invention;

[0036] Figure 8 The single-phase voltage transient rise waveform generated by the test system of the present invention;

[0037] Fig. 9 The three-phase voltage sag waveform generated by the test system of the present invention;

[0038] Fig.10 The two-phase voltage sag waveform generated by the test system of the present invention;

[0039] Fig.11 This is the single-phase voltage sag waveform generated by the test system of the present invention. DETAILED DESCRIPTION

[0040] The present invention provides a system and method for testing the overall performance of a dynamic voltage restorer. The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] The test system of this embodiment is suitable for performance testing of three-phase DVR devices with a rated voltage of 400V / 230V and a capacity not greater than 300kVA. Figure 1 As shown, the test power source uses a 400 / 230V three-phase four-wire AC voltage source, and the series branch three-phase contactless solid-state switch T1 is composed of 6 800A / 1200V thyristors. Two thyristors in each phase are connected in parallel in positive and negative directions and then connected in series with the reactor L0. The reactor uses a dry iron core series reactor with a rated current of 450A and a rated inductance of 0.84mH. The 400 / 230V three-phase power supply is connected to the input side of the series branch three-phase contactless solid-state switch T1, and the test product DVR device is connected to the output side of the series reactor L0. There are three groups of filter branches, among which C1 and L1 constitute a group of 3rd order filters, C2 and L2 constitute a group of 5th order filters, and C3 and L3 constitute a group of 7th order filters. The parameters are C1=1473.66uF, L1=0.764mH, C2=1987.37uF, L2=0.204mH, C3=1987.37uF, L3=0.104mH. The capacitive compensation capacity of the three branches at 400V voltage is 80kvar, 110kvar and 1100kvar respectively, and the total compensation capacity is 300kvar. The three-phase shunt reactor L4 in the controllable reactor branch has a capacity of 300kvar, a rated current of 435A, a star connection, a rated inductance of 1.68mH, and a three-phase iron core shunt reactor. The capacity of the thyristor valve group T2 matches the reactor, and it is composed of 6 800A / 1200V thyristors. Two thyristors in each phase are connected in parallel in positive and negative directions and are connected to the three-phase shunt reactor L4 respectively. The phase-splitting contactor K of the shunt resistor branch adopts a phase-splitting controllable contactor. The shunt resistor R has a rated current of 116A, a rated resistance of 1.98Ω, a single-phase capacity of 27kW (resistive), and a three-phase capacity of 80kW (resistive).

[0042] The dynamic voltage restorer (DVR) whole machine performance test system of this embodiment has four working modes, which are divided into DVR charging test mode, voltage interruption test mode, voltage swell test mode, and voltage sag test mode. The following describes these four modes in detail:

[0043] In the DVR charging mode, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, and the test power supply is added to the input side of the test DVR device through the three-phase series reactor L0, and the filter compensation branch and the controllable reactor branch are put into operation. When the three-phase split-phase switching contactor K is disconnected, the resistive load on the output side of the test DVR device is 0kW; when the three-phase split-phase switching contactor K is turned on, the resistive load on the output side of the test DVR device is 80kW; when the single-phase split-phase switching contactor K is turned on, the conducting phase power is 26kW and the non-conducting phase power is 0kW, thereby simulating an unbalanced resistive load. Due to the existence of the charging and output side loads of the test DVR device, the voltage on the input side of the DVR device decreases. If no measures are taken, the voltage decreases to the action range of the test DVR device, and the DVR device will malfunction. Therefore, it is necessary to ensure that the voltage on the input side of the test DVR device remains stable. This function is achieved by adjusting the trigger angle of the thyristor valve group of the controllable reactor branch. When the voltage on the input side of the DVR device is lower than the target voltage value, the trigger angle of the thyristor valve group of the controllable reactor branch is increased to reduce the output capacity of the controllable reactor; when the voltage on the input side of the DVR device is higher than the target voltage value, the trigger angle of the thyristor valve group of the controllable reactor branch is reduced to increase the output capacity of the controllable reactor; when the voltage on the input side of the DVR device is equal to the target voltage value, the state of the controllable reactor is maintained unchanged. The filter branch remains in the input state unchanged, absorbs the harmonic current generated by the controllable reactor branch, and generates a fixed capacitive reactive power at the same time, and cooperates with the controllable reactor branch to stabilize the input side voltage of the test DVR device. In the DVR charging mode, through the coordination of the controllable reactor branch, the parallel resistor branch and the filter compensation branch, the test DVR device can pass the current corresponding to the rated power to verify the current-carrying capacity and temperature rise characteristics of the internal bypass thyristor. At the same time, the reactive power on the input and output sides of the test DVR cancel each other out, and the power flowing through the series branch and the test power supply is small, which reduces the test power supply capacity requirement.

[0044] After the DVR is fully charged, the three-phase voltage interruption can be formed by stopping the triggering signal of the A-phase, B-phase, and C-phase parallel thyristors in the three-phase contactless solid-state switch T1 of the series branch. Figure 2 Stopping the trigger signals of any two phases of the A-phase, B-phase, and C-phase anti-parallel thyristors in the three-phase contactless solid-state switch T1 in the series branch can form a two-phase voltage interruption, as shown in FIG. Figure 3 Stopping the trigger signal of any phase of the A-phase, B-phase, and C-phase parallel thyristors in the three-phase contactless solid-state switch T1 in the series branch can form a single-phase voltage interruption, as shown in FIG. Figure 4 As shown. As needed, after stopping the trigger for a period of time, the trigger signal can be restored, and then the trigger signal can be stopped again to generate a continuous voltage interruption signal, such as Figure 5 As shown, the reclosing failure conditions encountered in actual projects can be simulated.

[0045] After the test DVR is fully charged, by changing the triggering angle of the thyristor valve group T2 of the controllable reactor branch, voltage swells of varying degrees can be simulated. In the initial state, the test DVR is fully charged, all filter compensation branches are put into operation, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the thyristor valve group T2 of the controllable reactor branch is in the 90-degree triggering mode, and at least one phase of the parallel resistor branch is put into operation. In the initial stage of voltage swell, the triggering angle of the thyristor valve group T2 of the controllable reactor branch quickly shifts from the 90-degree triggering mode to the target angle (the larger the angle, the greater the voltage swell, which can be set according to the voltage swell amplitude requirements), and the duration can be set. When the three-phase triggering angles increase at the same time, a three-phase voltage swell occurs, such as Figure 6 As shown in the figure, when the two-phase trigger angle increases at the same time, the two-phase voltage temporarily rises, such as Figure 7 As shown; when the single-phase trigger angle increases, the single-phase voltage temporarily rises, such as Figure 8 As shown; through this mode, it can be verified whether the DVR under test can respond correctly in the voltage swell mode.

[0046] After the test DVR is fully charged, one or two groups of filter compensation branches are withdrawn, and the triggering angle of the thyristor valve group T2 of the controllable reactor branch is changed to simulate voltage sags of different degrees. In the initial state, the test DVR is fully charged, at least one group of filter compensation branches is withdrawn, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the thyristor valve group T2 of the controllable reactor branch is at a triggering angle to maintain the current voltage on the inlet side of the DVR device at 400 / 230V, and at least one phase of the parallel resistor branch is put into operation. In the initial stage of voltage sag, the triggering angle of the thyristor valve group T2 of the controllable reactor branch quickly shifts from the current triggering mode to the target angle (the smaller the angle, the greater the voltage sag, which can be set according to the voltage sag amplitude requirements), and the duration can be set. When the three-phase trigger angles are reduced at the same time, a three-phase voltage sag occurs, such as Fig. 9 As shown; when the two-phase trigger angles decrease at the same time, a two-phase voltage drop occurs, such as Fig.10 As shown; when only the single-phase trigger angle decreases, a single-phase voltage sag occurs, such as Fig.11 As shown; through this mode, it can be verified whether the DVR under test can respond correctly in the voltage sag mode.

[0047] This embodiment is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A dynamic voltage restorer whole machine performance test system, characterized in that: The system comprises a test power supply, a series branch, a filter compensation branch, a dynamic voltage restorer, a controllable reactor branch and a parallel resistor branch; wherein the test power supply, the series branch, the dynamic voltage restorer and the controllable reactor branch are sequentially connected in series, the controllable reactor branch is connected in parallel with the parallel resistor branch, and the filter compensation branch is connected in parallel with the dynamic voltage restorer at the input side of the dynamic voltage restorer; The series branch is composed of a three-phase contactless solid-state switch T1 and a three-phase series reactor L0 connected in series, wherein the three-phase contactless solid-state switch T1 is connected to the test power supply, and the three-phase series reactor L0 is connected to the input side of the dynamic voltage restorer; The filter compensation branch is composed of a three-phase filter capacitor and a three-phase filter reactor connected in series, and the three-phase filter reactor is connected to the neutral line in star shape; The dynamic voltage restorer comprises a bypass thyristor, a voltage source converter and an energy storage device, wherein the bypass thyristor is arranged between corresponding phases of the input side and the output side of the dynamic voltage restorer, the voltage source converter is connected in parallel to the output side of the dynamic voltage restorer, and the energy storage device is installed on the DC side of the voltage source converter; The controllable reactor branch is composed of a thyristor valve group T2 and a three-phase shunt reactor L4 connected in series, wherein the thyristor valve group T2 is connected to the output side of the dynamic voltage restorer, and the three-phase shunt reactor L4 is connected to the neutral line in a star shape; The parallel resistor branch is composed of a phase-splitting contactor K and a parallel resistor R connected in series, wherein the phase-splitting contactor K is connected to the output side of the dynamic voltage restorer, and the parallel resistor R is connected to the neutral line in a star shape.

2. The dynamic voltage restorer whole machine performance test system according to claim 1, characterized in that: The filtering and compensating branches are provided in one group or in multiple groups in parallel as required.

3. The dynamic voltage restorer whole machine performance test system according to claim 1, characterized in that: The three-phase contactless solid-state switch T1 conducts one phase, two phases or three phases as required.

4. The dynamic voltage restorer whole machine performance test system according to claim 1, characterized in that: The energy storage device is a super capacitor or a lithium iron phosphate battery.

5. The dynamic voltage restorer whole machine performance test system according to claim 1, characterized in that: The thyristor valve group T2 includes 6 thyristors, 2 thyristors are anti-parallel connected in each phase and the trigger angle range of each thyristor is 90° to 180°.

6. The dynamic voltage restorer whole machine performance test system according to claim 1, characterized in that: The three-phase capacity of the controllable reactor branch is independently adjusted, and the capacity of each phase is continuously and smoothly outputted with an output range of 0-100%.

7. A testing method for the dynamic voltage restorer whole machine performance testing system according to claim 1, characterized in that: The test method of the system includes a dynamic voltage restorer charging test method, a voltage interruption test method, a voltage swell test method and a voltage sag test method; the dynamic voltage restorer charging test method is specifically as follows: The three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the test power is added to the input side of the dynamic voltage restorer through the three-phase series reactor L0, and the filter compensation branch and the controllable reactor branch are put into operation; the unbalanced resistive load is simulated by turning on and off each phase of the phase-splitting contactor K; the triggering angle of the thyristor valve group T2 of the controllable reactor branch is adjusted to keep the input side voltage of the dynamic voltage restorer stable; the filter compensation branch remains in the input state unchanged, absorbs the harmonic current generated by the controllable reactor branch, and generates a fixed capacitive reactive power at the same time, cooperating with the controllable reactor branch to stabilize the input side voltage of the dynamic voltage restorer.

8. The testing method of the dynamic voltage restorer whole machine performance testing system according to claim 7, characterized in that: The voltage interruption test method is as follows: After the dynamic voltage restorer is charged, the trigger signal of one phase, two phases or three phases in the three-phase contactless solid-state switch T1 of the series branch is stopped, forming a voltage interruption; then the trigger signal of the three-phase contactless solid-state switch T1 is restored, and then the triggering is stopped again, forming a continuous voltage interruption to simulate the reclosing failure condition.

9. The testing method of the dynamic voltage restorer whole machine performance testing system according to claim 7, characterized in that: The voltage swell test method is as follows: The dynamic voltage restorer is charged, all filter compensation branches are put into operation, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, the thyristor valve group T2 of the controllable reactor branch is in the 90-degree trigger mode, and at least one phase of the parallel resistor branch is put into operation; in the initial stage of voltage swell, the one-phase, two-phase or three-phase trigger angle of the thyristor valve group T2 of the controllable reactor branch is quickly shifted from 90 degrees to the target angle to verify whether the dynamic voltage restorer can respond correctly.

10. The testing method of the dynamic voltage restorer whole machine performance testing system according to claim 7, characterized in that: The voltage sag test method is as follows: After the dynamic voltage restorer is charged, one or two groups of filter compensation branches are exited, the three-phase contactless solid-state switch T1 of the series branch is continuously turned on, and the triggering angle of the thyristor valve group T2 of the controllable reactor branch is changed to maintain the current input side voltage of the dynamic voltage restorer at the voltage of the test power supply, and at least one phase of the parallel resistor branch is put into operation; in the initial stage of voltage sag, the one-phase, two-phase or three-phase triggering angle of the thyristor valve group T2 is quickly shifted from the current triggering mode to the target angle to verify whether the dynamic voltage restorer can respond correctly.

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