CN103033701B - The high-power operating test device of flexible direct current transmission converter valve stable state and test method - Google Patents

Abstract

The invention relates to a test device and test method for steady-state high-power operation of a flexible direct current transmission converter valve. The test device includes an isolation transformer (TR1), a rectifier bridge (REC1) and a valve group of a converter valve. The input end is connected to the isolation transformer, and its DC output end is connected to the converter valve valve group. The experimental device also includes a BUCK-BOOST buck-boost circuit, which includes an IGBT module composed of an IGBT and an anti-parallel diode, a resistor (R), DC bus support capacitor (C1) and load reactor (L1), the resistor (R) is connected in series with the IGBT module and connected in parallel to the DC output end of the rectifier bridge (REC1), and the DC bus support capacitor (C1 ) are connected in parallel at both ends of the series branch of the resistor (R) and the IGBT module, and are connected to the valve group of the converter valve through the load reactor (L1). By constructing the same test platform as the actual steady-state operating conditions, the steady-state power operation test of the converter valve is carried out, and the current, voltage and temperature rise of the components are detected to verify the correctness of the converter valve design.

Description

Test device and test method for steady-state high-power operation of flexible HVDC converter valve

technical field

The invention relates to a test device and a test method for steady-state high-power operation of a flexible DC transmission converter valve.

Background technique

Since flexible direct current transmission (VSC-HVDC) devices generally have the characteristics of high voltage, high current, and large capacity, it is difficult to construct a full-load circuit in the test environment that is the same as the actual operating condition for testing. Therefore, how to test in the test environment It is the key to solve the problem to construct an equivalent test circuit and conduct a test with the strength equivalent to the actual operating condition.

VSC-HVDC based on modular multi-level converter valves is a new technology that uses IGBT valves for DC power transmission. The sub-module (SM) is the smallest power unit that constitutes the converter valve. Capacitors are connected in parallel, and several sub-modules are connected in series to form a converter valve assembly, which can reflect the electrical characteristics of the converter valve in proportion, and is the basic electrical unit for the steady-state operation test of the converter valve.

Usually, a VSC-HVDC converter valve engineering project includes thousands of sub-modules. If the steady-state power test is performed on all sub-modules one by one, it will be a time-consuming and labor-intensive project. The purpose of the steady-state power test is to The process link is tested to check whether there is an abnormal temperature rise of the components. Therefore, the scientific and simple high-power steady-state test method of the flexible direct current transmission converter valve is particularly important, which can lay a good foundation for the mass production of the flexible direct current transmission converter valve.

Contents of the invention

The purpose of the present invention is to provide a flexible DC transmission converter valve steady-state high-power operation test device and test method. By constructing a full-load circuit that is the same as the actual operating condition, the steady-state power operation test of the converter valve is performed, and the component current , voltage and temperature rise detection, and verify the correctness of the design of the converter valve.

In order to achieve the above object, the device solution of the present invention is: a flexible direct current transmission converter valve steady-state high-power operation test device, including an isolation transformer (TR1), a rectifier bridge (REC1) and a converter valve group, the rectifier The AC input end of the bridge is connected to the isolation transformer, and its DC output end is connected to the converter valve group. The test device also includes a BUCK-BOOST buck-boost circuit, which includes a first IGBT and anti-parallel diode. An IGBT module, a first resistor (R), a DC bus support capacitor (C1) and a load reactor (L1), the first resistor (R) is connected in series with the first IGBT module and connected in parallel to the DC of the rectifier bridge (REC1) At the output end, the DC bus support capacitor (C1) is connected in parallel to both ends of the series branch of the first resistor (R) and the first IGBT module, and is connected to the valve group of the converter valve through the load reactor (L1).

The test device is also equipped with a circuit breaker input switch (KM), a three-phase voltage regulator (TY) and a filter reactor (LR). The circuit breaker input switch (KM) is connected to a three-phase power supply and The reactor (TY), the filter reactor (LR) and the isolation transformer (TR1) are connected in series in sequence.

The converter valve group is composed of a series of converter valve sub-modules, including a converter valve sub-module put into operation and a redundant converter valve sub-module.

The converter valve sub-module is composed of a sub-module bypass switch (K1n), two second IGBT modules (T1n and T1m), a thyristor (Tn), a sub-module capacitor (C _SM1N ) and a second resistor (R1n). The second IGBT module is composed of an IGBT device and an anti-parallel diode, the two second IGBT modules (T1n and T1m) are connected in series, and the second resistor (R1n) and the sub-module capacitor (C _SM1N ) are sequentially connected in parallel between the two The two ends of the series branch of two second IGBT modules (T1n and T1m), the bypass switch (K1n) and the thyristor (Tn) are sequentially connected in parallel at both ends of one of the second IGBT modules (T1m).

The method scheme of the present invention is: a flexible direct current transmission converter valve steady-state high-power operation test method, the steps are as follows:

(1) Set the sub-module capacitor voltage and calculate the DC bus support capacitor voltage, close the input switch (KM) of the AC side circuit breaker of the test device, and the test device starts to start;

(2) When the DC bus supporting capacitor voltage reaches the calculated voltage value, the DC bus is controlled to charge the capacitors of the converter valve sub-modules in series through the load reactor until the capacitor voltage of each sub-module reaches the set voltage value , the test device is started;

(3) After the test device is started, a trigger pulse is sent to the IGBT of each series-connected converter valve sub-module, and the capacitance of each series-connected converter valve sub-module is discharged to the DC bus through the load reactor. Afterwards, the test device continuously repeated the capacitor charging and discharging process of the converter valve sub-module, and the circuit entered a steady-state operation state;

(4) When a fault of a converter valve sub-module in the converter valve group is detected during the test operation, the bypass switch of the faulty sub-module is closed to bypass the faulty sub-module, and at the same time, a redundant The bypass switch of the converter valve sub-module is disconnected and put into operation;

(5) Block the trigger pulse of the IGBT of the converter valve sub-module, output the trigger pulse of the IGBT of the discharge circuit, release the capacitor energy of the DC bus, and end the test; or, disconnect the input switch (KM) of the circuit breaker, and pass The LC loop composed of capacitor (C1) and load reactor (L1) releases the energy of the system, and the test ends;

(6) After the test of a group of converter valve sub-modules is completed, the next group of converter valve sub-modules to be tested can be replaced, and steps (1) to (5) can be performed again.

The calculation method of the DC bus support capacitor voltage is: U _dc = U _c n _SM /2, wherein U _dc is the DC bus support capacitor voltage, U _c converter valve sub-module capacitor voltage, and n _SM is the test put into operation The number of converter valve sub-modules.

In step (3), the pulse modulation of the converter valve sub-module adopts a phase shift pulse width modulation method.

The beneficial effects achieved by the present invention: the present invention builds a test platform similar to the actual steady-state operating conditions, and a group of redundant sub-modules are also provided in the valve group of the converter valve. When a sub-module failure in operation is detected , the faulty sub-module can be bypassed through the bypass switch, and a corresponding redundant sub-module can be put into operation, realizing the steady-state performance test of the power loop under the conditions of high voltage, high current and stable thermal intensity of multiple sub-modules, which can be Meet the requirement of testing multiple sub-modules at the same time.

Moreover, the present invention only realizes charging and discharging of the capacitor through a buck-boost circuit, and observes changes in the current and voltage of the sub-module. The control method is simple, the operation is flexible, and the actual steady-state operating conditions of the sub-module can be well reproduced.

Description of drawings

Fig. 1 is a schematic diagram of the test device of the present invention;

Fig. 2 is a circuit structure diagram of the converter valve sub-module of the present invention;

Fig. 3 is a waveform diagram of the capacitive voltage of the test device of the present invention;

Fig. 4 is the current waveform diagram of the load reactor of the test device of the present invention;

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Device embodiment of the present invention:

As shown in Figure 1, the test device of the present invention includes an input circuit breaker switch KM, a three-phase voltage regulator TY, a filter reactor LR, an isolation transformer TR, a rectifier bridge REC1, a BUCK-BOOST buck-boost circuit and a converter valve group. The converter valve group is composed of n+k converter valve sub-modules SM1~SM(n+k) in series, including k redundant sub-modules, and the number of sub-modules actually put into operation is n. The group is connected in parallel at the DC output end of the rectifier bridge. The BUCK-BOOST buck-boost circuit includes the first IGBT module T, the first resistor R1 connected in series with the first IGBT module T, the DC bus support capacitor C1 and the load reactor L1. The bus support capacitor C1 is connected in parallel to both ends of the series branch of the first IGBT module T and the first resistor R1, and the rectifier bridge REC1 is connected to the converter valve group through the load reactor L1.

The converter valve sub-module of the device includes two series-connected half-bridge structures and sub-module capacitors. The half-bridge structure includes a bypass switch K1n, a second resistor R1n, a thyristor Tn, two second IGBT modules T1n and T1m, and a second The IGBT module consists of an IGBT device and an anti-parallel diode. The second IGBT module T1n and T1 are connected in series. The second resistor R1n and the sub-module capacitor C _{SM1N are} sequentially connected in parallel at both ends of the series branch of T1n and T1m. The bypass switch K1n Thyristors Tn are sequentially connected in parallel at both ends of T1m, each converter valve sub-module is connected in series through their respective bypass switches, the bypass switches of each converter valve sub-module put into operation are disconnected, and the bypass switches of the other redundant When one of the sub-modules put into operation fails, the bypass switch of the sub-module is closed, the sub-module is bypassed, and the bypass switch of a redundant sub-module is disconnected, and it is put into operation. Run to ensure that the number of sub-modules in the test run remains unchanged.

Embodiment of the inventive method:

A. Set the capacitor voltage of the converter valve sub-module, and calculate the DC bus capacitor voltage according to the formula U _dc = U _c n _SM /2, where U _dc is the DC bus capacitor voltage, U _c is the sub-module capacitor voltage, n _SM is the number of serial sub-modules actually put into operation;

B. When the test is started, soft start is realized by the AC input terminal first. When the DC bus capacitor voltage reaches U _dc , the test device is controlled to charge the capacitors of each series sub-module from the DC bus through the load reactor, according to the BOOST boost mode Run, and monitor the capacitor voltage of each sub-module until the capacitor voltage of each sub-module is U _c , then the start-up is completed;

C. The sub-modules in series are discharged to the DC bus through the load reactor, and the IGBT trigger pulse is issued to make the circuit operate in the BUCK step-down mode. After that, the test device continuously repeats the above-mentioned BUCK-BOOST operation mode to simulate the actual steady-state operating conditions of the sub-modules. .

D. After the experiment is over, block the trigger pulse of the IGBT, output the IGBT trigger pulse of the discharge circuit, and release the energy of the DC bus capacitor, or after the experiment, disconnect the circuit breaker input switch (KM) to make the device work in the discharge mode, the system energy is released through the LC loop;

E. After the test is completed, all the sub-modules to be tested can be directly removed from the shelf, and the next batch of sub-modules to be tested can be replaced, and steps (A) to (E) can be performed again until all the sub-modules are tested.

When the test device of the present invention is running in a steady state, the measured converter valve group works in the phase-shift pulse width modulation mode, and the voltage waveform shown in Figure 3 is obtained at both ends of the converter valve group, including the sub-module capacitor voltage Waveform and system DC bus capacitor voltage waveform, through the pulse control of each sub-module IGBT, the charging and discharging process of the sub-module capacitor can be changed, and the current flowing through each sub-module can be controlled at the same time, so as to realize the steady-state high-power operation of multiple sub-modules at the same time The purpose of the test, and obtain the current waveform as shown in Figure 4, the present invention can meet the test requirements of different numbers of sub-modules by adjusting the output of the three-phase voltage regulator.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. After reading this application, those skilled in the art refer to the above embodiments to make various modifications or changes to the present invention, all of which are within the protection scope of the application claims within.

Claims (7)

1. a kind of high-power operating test device of flexible direct current transmission converter valve stable state, including isolating transformer (TR1), rectifier bridge (REC1) and converter valve valve group, the ac input end connection isolating transformer of the rectifier bridge, the connection change of current of its DC output end Valve valve group, it is characterised in that the experimental rig also includes a BUCK-BOOST step-up/step-down circuit, the BUCK-BOOST liftings Volt circuit includes the first IGBT module being made up of IGBT device and anti-paralleled diode, first resistor (R), a dc bus Support Capacitor (C1) and load reactance device (L1), first resistor (R) are connected in parallel on the rectifier bridge after being connected with the first IGBT module (REC1) DC output end, the dc bus Support Capacitor (C1) is connected in parallel on first resistor (R) and the first IGBT module string Join the two ends of branch road, and converter valve valve group is connected by load reactance device (L1).

2. the high-power operating test device of flexible direct current transmission converter valve stable state according to claim 1, it is characterised in that The experimental rig is additionally provided with breaker input switch (KM), three-phase regulator (TY) and filter reactor (LR), the breaker Input switch (KM) connect three phase mains, and with three-phase regulator (TY), filter reactor (LR) and isolating transformer (TR1) according to Secondary series connection.

3. the high-power operating test device of flexible direct current transmission converter valve stable state according to claim 1, it is characterised in that The converter valve valve group is made up of the converter valve submodule of one group of series connection, including the converter valve submodule and redundancy that put into operation are changed Flow valve submodule.

4. the high-power operating test device of flexible direct current transmission converter valve stable state according to claim 3, it is characterised in that The converter valve submodule by submodule by-pass switch, IGBT module T1n, IGBT module T1m, IGCT, submodule electric capacity and Second resistance is constituted, and the IGBT module T1n and IGBT module T1m are by an IGBT device and an antiparallel diode Composition, IGBT module T1n and IGBT module the T1m series connection, second resistance is connected in parallel on by IGBT moulds successively with submodule electric capacity The two ends of the series arm of block T1n and IGBT module T1m compositions, submodule by-pass switch, IGCT are connected in parallel on IGBT moulds successively Block T1m two ends.

5. a kind of test method of experimental rig as claimed in claim 4, it is characterised in that step is as follows:

(1) set submodule capacitor voltage and calculate dc bus Support Capacitor (C1) voltage, closure experimental rig AC breaks Road device input switch (KM), experimental rig starts to start；

(2) when dc bus Support Capacitor (C1) voltage reaches the magnitude of voltage calculated, control dc bus is through load reactance Device (L1) charges to the submodule electric capacity of the converter valve submodule of each series connection, until each submodule capacitor voltage reaches setting electricity During pressure value, experimental rig, which starts, to be finished；

(3) after experimental rig startup is finished, the IGBT device to each series connection converter valve submodule sends out trigger pulse, by each series connection The submodule electric capacity of converter valve submodule is discharged through load reactance device (L1) to dc bus, and afterwards, experimental rig is constantly repeated The submodule capacitor charge and discharge process of converter valve submodule, circuit enters steady-state operating condition；

(4) when detecting in converter valve valve group converter valve sub-module fault during test run, the failure is closed The submodule by-pass switch of converter valve submodule, the failure converter valve submodule is bypassed, meanwhile, by redundancy converter valve The submodule by-pass switch of module disconnects, and is put into operation；

(5) trigger pulse of locking converter valve submodule IGBT device, exports bleed-off circuit IGBT device trigger pulse, by direct current The release of bus Support Capacitor (C1) energy is finished, off-test；Or, cut-off breaker input switch (KM), by by direct current The LC loops of bus Support Capacitor (C1) and load reactance device (L1) composition finish system capacity release, off-test；

(6) after one group of converter valve submodule test is completed, replaceable next group converter valve submodule to be tested is held again Row step (1)~(5).

6. test method according to claim 5, it is characterised in that the meter of dc bus Support Capacitor (C1) voltage Calculation method is：U_dc=U_c·n_SM/ 2, wherein, U_dcFor dc bus Support Capacitor (C1) voltage, U_cThe submodule of converter valve submodule Block capacitance voltage, n_SMTo test the converter valve submodule number put into operation.

7. test method according to claim 5, it is characterised in that adjusted in step (3) to the pulse of converter valve submodule System uses phase-shifted pulse width modulation mode.