CN110244217B - Test method for hybrid high-voltage direct-current circuit breaker - Google Patents

Abstract

A test method for a hybrid high-voltage direct-current circuit breaker. According to the invention, through the four parts of the auxiliary through-current branch consisting of the low-voltage large current source, the test inductor and the power electronic module and the parallel overvoltage protection branch, the continuous and stable test current is generated by the auxiliary through-current branch consisting of the low-voltage large current source and the power electronic module, and then the current provided by the continuous operation test circuit is converted to the test product, namely the hybrid high-voltage direct-current circuit breaker, so that the investigation of the rated current closing test capability of the test product is completed.

Description

A test method for hybrid HVDC circuit breakers

technical field

The invention relates to the field of power electronics detection, in particular to a test method for a hybrid high-voltage direct current circuit breaker.

Background technique

Hybrid HVDC circuit breaker is an important device to maintain the reliable operation of HVDC grid. It breaks the current through the power electronics. When the circuit breaker is in normal operation, the on-state loss is small, and the breaking time period is realized. During the breaking process, the DC circuit breaker responds to the faults at different stages according to the timing sequence set by itself, and performs different fault handling steps.

However, there is currently no proper way to realize the failure of the existing hybrid high-voltage direct current circuit breaker itself. Existing methods can only simulate line faults in the state of low voltage and low current, and simulate fault detection and response operations. The reason is that the high-voltage and high-current state of the hybrid high-voltage DC circuit breaker will cause an impact on the circuit of the test instrument and damage the test equipment during fault test detection.

Contents of the invention

In order to solve the deficiencies in the prior art, the object of the present invention is to provide a test method for a hybrid high-voltage direct current circuit breaker.

First of all, in order to achieve the above purpose, a test method for hybrid high-voltage DC circuit breakers is proposed, the steps include: the first step, build a test circuit, the test circuit includes: low-voltage high-current source, test inductance, protection Branch and auxiliary co-current branch; wherein, after the protection branch and the auxiliary flow branch are connected in parallel with the hybrid high-voltage DC circuit breaker, the low-voltage high-current source is connected through the test inductance; the second step , start the low-voltage high-current source, and provide continuous and stable test current to the hybrid high-voltage DC circuit breaker and the auxiliary current flow branch; in the third step, the auxiliary current flow circuit receives the test current. After the experimental current is stable, it is blocked to inject a high-voltage experimental current into the hybrid high-voltage direct current circuit breaker, completes the commutation to the hybrid high-voltage direct current circuit breaker, and then blocks; the fourth step, the hybrid high-voltage direct current circuit breaker The circuit breaker is triggered by the high-voltage experimental current, and can be reliably contacted to complete the closing operation according to the internal control sequence of the hybrid high-voltage DC circuit breaker during the blocking period of the auxiliary current flow branch; in the fifth step, the auxiliary After the closing operation of the hybrid high-voltage DC circuit breaker is completed, the flow-through circuit receives the test current transferred back by the hybrid high-voltage DC circuit breaker; in the above steps, the protection branch always detects that the hybrid The sampling point voltage of the high-voltage DC circuit breaker is used for overvoltage protection of the hybrid high-voltage DC circuit breaker; the test inductance generates an induced potential when the test current fluctuates to offset the test current fluctuation.

Optionally, in the above test method, in the test circuit built in the first step, the low-voltage high-current source is composed of a thyristor rectifier.

Optionally, in the above test method, in the test circuit built in the first step, the auxiliary flow branch is composed of an IGBT device and an energy storage element.

Optionally, in the above test method, in the test circuit built in the first step, the energy storage element in the auxiliary flow branch is a double-layer metallized film capacitor or a polypropylene non-polar capacitor.

Optionally, in the above test method, in the test circuit built in the first step, the stray inductance of the energy storage element is lower than 50nH.

Optionally, in the above test method, in the test circuit built in the first step, the auxiliary flow branch includes at least one pair of parallel auxiliary flow valves.

Optionally, in the above test method, in the test circuit built in the first step, each of the auxiliary flow valves includes at least two groups of unit circuits, and each group of unit circuits is connected in parallel to the Both ends of the protection circuit; each group of unit circuits includes: 4 IGBT devices and 1 capacitor; wherein, the emitter of the first IGBT device is connected to the first pin of the capacitor and the second IGBT device The emitter of the first IGBT device, the collector of the first IGBT device is connected to the emitter of the fourth IGBT device, the collector of the fourth IGBT device is connected to the collector of the third IGBT device and the second pin of the capacitor, The emitter of the third IGBT device is connected to the collector of the second IGBT device, and a switch is connected in series between the emitter of the third IGBT device and the emitter of the fourth IGBT device The element is used for controlling the flow state of the current in the auxiliary flow branch.

Optionally, in the above-mentioned test method, in the test circuit built in the first step, in the protection branch, the thyristor is connected in series with the low-voltage high-current source and the test inductor through its positive and negative poles, so that The gate level of the crystal gate is connected to the overvoltage judgment circuit, and the overvoltage judgment circuit compares the sampling voltage obtained by it with the reference voltage input to it, and outputs a control signal to the crystal gate when the sampling voltage is greater than the reference voltage to switch the protection branch to a protection state.

Optionally, in the above-mentioned test method, in the test circuit built in the first step, the maximum repeatable peak current of the collector accumulated by each IGBT device in the auxiliary flow-through valve reaches at least as high as that of the hybrid high-voltage direct current circuit breaker. rated current of the device.

Beneficial effect

The invention designs a new device for hybrid high-voltage DC circuit breaker test, which includes four parts: a low-voltage high-current source, a test inductance, an auxiliary current branch circuit composed of a power electronic module, and a parallel overvoltage protection branch circuit. It uses an auxiliary flow branch composed of a low-voltage high-current source and a power electronic module to generate a continuous and stable test current, and then commutates the current provided by the continuous operation test circuit to the test product through the auxiliary flow branch, that is, the hybrid high-voltage DC circuit breaker, so as to complete the inspection of the rated current closing test capability of the test product.

The test device designed in this patent can accurately control the current stress of the test product through the commutation function of the auxiliary flow branch, and realize the reproduction of the closing stress, so as not to endanger the test product itself.

Moreover, the test method designed in this patent simplifies the design of precise control of the power supply in the test device, reduces the difficulty of the overall timing control of the test method through the commutation of the auxiliary flow branch, and greatly reduces the test capacity.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, and together with the embodiments of the present invention, are used to explain the present invention, and do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is a schematic circuit structure diagram of a hybrid high-voltage direct current circuit breaker according to the present invention;

Fig. 2 is the circuit block diagram according to experimental device of the present invention;

Fig. 3 is a schematic circuit diagram of the auxiliary flow valve in the experimental device of the present invention.

Detailed ways

The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Flexible DC transmission has many technical advantages, and has become one of the hot transmission technologies in the international power field, and will also be an important part of the future grid construction. Due to the low damping characteristics of the DC system, compared with the AC system, the faults of the DC system develop faster, and the control and protection are more difficult. High-voltage DC circuit breakers are urgently needed for DC fault isolation and fast fault recovery. High-voltage DC circuit breaker is an important foundation and one of the key equipment for the construction of DC power grid.

Hybrid high-voltage DC circuit breakers are the mainstream technical route of high-voltage DC circuit breakers. Referring to Figure 1, the hybrid HVDC circuit breaker includes a main branch composed of fast mechanical switches and a small number of power electronic modules connected in series, a transfer branch composed of a large number of power electronic modules connected in series, and an energy consumption branch composed of arresters connected in series and parallel. road.

A feasible experimental device for the hybrid high-voltage DC circuit breaker in Fig. 1 provided by the present invention can refer to Fig. 2 for its circuit principle. It can be used for rated current closing test and short-time current withstand test for hybrid high-voltage DC circuit breakers. It is mainly to test the correctness of the closing performance of the hybrid HVDC circuit breaker and the design of the control and protection unit. Since there is no type test standard for DC circuit breakers available at present, a method for effectively verifying the rated current making capacity of hybrid HVDC circuit breakers can lay a foundation for the popularization and application of HVDC circuit breakers and the formulation of test standards.

Among them, the test device includes four parts: a low-voltage high-current source, a test inductor, and an auxiliary current flow branch composed of power electronic modules and a parallel overvoltage protection branch; the low-voltage high-current The high voltage is generated during the commutation process of the current circuit to the DC circuit breaker, so that the DC circuit breaker can be reliably connected; the test inductance is used to reduce the fluctuation of the test current; the auxiliary current branch is used to carry the test current and complete the commutation to the circuit of the test product; The parallel protection branch is used for overvoltage protection of the test product.

The low-voltage high-current source is composed of thyristor rectifiers, which can provide continuous, stable and adjustable constant current.

The auxiliary current branch is composed of IGBT devices and energy storage components, which can effectively realize long-term current flow, commutation and IGBT soft shutdown, and can be used to carry the test current and complete the two-way commutation to the circuit of the test product. As shown in Figure 3: the auxiliary flow branch includes at least one pair of parallel auxiliary flow valves. Wherein, each of the auxiliary flow valves includes at least two groups of unit circuits, and each group of unit circuits is connected in parallel to both ends of the protection circuit; each group of unit circuits includes: 4 IGBT devices and 1 capacitor; wherein, the emitter of the first IGBT device is connected to the first pin of the capacitor and the emitter of the second IGBT device, and the collector of the first IGBT device is connected to the emitter of the fourth IGBT device pole, the collector of the fourth IGBT device is connected to the collector of the third IGBT device and the second pin of the capacitor, the emitter of the third IGBT device is connected to the collector of the second IGBT device The electrodes are connected, and a switching element is connected in series between the emitter of the third IGBT device and the emitter of the fourth IGBT device, which is used to control the flow state of the current in the auxiliary current flow branch; each group The unit circuits are connected in series through the collector of the first IGBT device and the collector of the second IGBT device.

The parallel overvoltage protection branch is composed of series thyristors and an overvoltage judgment circuit, which can realize the overvoltage protection of the test product.

Wherein, the energy storage element in the auxiliary flow branch is a double-layer metallized film capacitor or a polypropylene non-polar capacitor. The stray inductance of the energy storage element is lower than 50nH.

When the above-mentioned device is used for the hybrid high-voltage DC circuit breaker test, the auxiliary current branch composed of the low-voltage high-current source and the power electronic module generates a continuous and stable test current, and then the current provided by the continuous operation test circuit is replaced by the auxiliary current branch. Flow to the test object, namely the hybrid HVDC circuit breaker. The circuit breaker completes the closing action, so as to realize the investigation of the closing performance of the DC circuit breaker and the overall control and protection unit of the circuit breaker. After the test object completes the closing operation, the test device transfers the test current back to the auxiliary flow branch of the power electronic module.

Before the test, connect the hybrid high-voltage DC circuit breaker to the test circuit, select a suitable test inductance, and then complete the power-on of the low-voltage high-current source and the auxiliary current branch, and adjust the current to the rated current value; after the current is stable, trigger the hybrid circuit breaker. The high-voltage DC circuit breaker transfers the branch, and at the same time blocks the auxiliary flow branch to commutate the current to the test product, that is, the hybrid high-voltage DC circuit breaker; the circuit breaker completes the closing action according to the internal control sequence, thereby realizing the closing of the DC circuit breaker Inspection of the performance and the overall control and protection unit of the circuit breaker; after the closing operation is completed, the test device transfers the test current back to the auxiliary flow branch; the low-voltage high-current source is turned off, and the test ends after the current of the test circuit drops to zero.

The invention adopts the auxiliary flow branch composed of low-voltage high-current source and power electronic module to generate continuous and stable test current, and then commutates the current provided by the continuous operation test circuit to the test product through the auxiliary flow branch, that is, the hybrid high-voltage DC circuit breaker. The circuit breaker completes the closing action, so as to realize the investigation of the closing performance of the DC circuit breaker and the overall control and protection unit of the circuit breaker. After the test object completes the closing operation, the test device transfers the test current back to the auxiliary flow branch of the power electronic module. Therefore, the present invention can solve the problem that the hybrid high-voltage direct current circuit breaker has high requirements on the voltage and current of the test equipment and is difficult to realize.

Those of ordinary skill in the art can understand that: the above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. A test method for a hybrid high-voltage direct current circuit breaker, characterized in that the steps include: The first step is to build a test circuit, which includes: a low-voltage high-current source, a test inductance, a protection branch and an auxiliary flow branch; wherein, the protection branch, the auxiliary flow branch and the mixed After the high-voltage DC circuit breakers are connected in parallel, the low-voltage high-current source is connected through the test inductance; The second step is to start the low-voltage high-current source to provide continuous and stable test current to the hybrid high-voltage DC circuit breaker and the auxiliary current flow branch; In the third step, the auxiliary current flow branch receives the test current, and after the test current is stable, it is blocked to inject a high-voltage test current into the hybrid high-voltage direct current circuit breaker, and completes the test current to the hybrid high-voltage direct current circuit breaker. commutator, and then blocked; In the fourth step, the hybrid high-voltage DC circuit breaker is triggered by the high-voltage experimental current, and is reliably contacted, so as to complete the shutdown according to the internal control sequence of the hybrid high-voltage DC circuit breaker during the blocking period of the auxiliary current branch. joint operation; Step 5: After the closing operation of the hybrid high voltage DC circuit breaker is completed, the auxiliary flow branch receives the test current transferred back by the hybrid high voltage DC circuit breaker; In the above steps, the protection branch always detects the sampling point voltage of the hybrid high-voltage DC circuit breaker, and performs overvoltage protection on the hybrid high-voltage DC circuit breaker; the test inductance is generated when the test current fluctuates. An induced potential to counteract this test current fluctuation; In the test circuit built in the first step, the auxiliary flow branch is composed of IGBT devices and energy storage elements; In the test circuit built in the first step, the stray inductance of the energy storage element is lower than 50nH; in the test circuit built in the first step, the auxiliary current flow branch includes at least one pair of parallel Auxiliary flow valve; In the test circuit built in the first step, each of the auxiliary flow valves includes at least two groups of unit circuits, and each group of unit circuits is connected in parallel to both ends of the protection branch; Each group of unit circuits includes: 4 IGBT devices and 1 capacitor; Wherein, the emitter of the first IGBT device is connected to the first pin of the capacitor and the emitter of the second IGBT device, the collector of the first IGBT device is connected to the emitter of the fourth IGBT device, and the fourth The collector of the IGBT device is simultaneously connected to the collector of the third IGBT device and the second pin of the capacitor, the emitter of the third IGBT device is connected to the collector of the second IGBT device, and the A switching element is further connected in series between the emitter of the third IGBT device and the emitter of the fourth IGBT device, for controlling the flow state of the current in the auxiliary current flow branch. 2. The test method for hybrid high-voltage direct current circuit breaker as claimed in claim 1, characterized in that, in the test circuit built in the first step, the low-voltage high-current source is composed of a thyristor rectifier. 3. The test method for hybrid high-voltage direct current circuit breaker as claimed in claim 1, characterized in that, in the test circuit built in the first step, the energy storage element in the auxiliary flow branch is Double layer metallized film capacitor or polypropylene electrodeless capacitor. 4. The test method for hybrid high-voltage DC circuit breakers as claimed in any one of claims 1-3, characterized in that, in the test circuit built in the first step, in the protection branch, the thyristor Through its positive and negative poles connected in series with the low-voltage high-current source and the test inductance, the gate level of the thyristor is connected to an overvoltage determination circuit, and the overvoltage determination circuit compares the sampling voltage obtained by it with the reference voltage input to it, When the sampling voltage is greater than the reference voltage, a control signal is output to the gate stage of the thyristor to switch the protection branch to a protection state. 5. The test method for hybrid high-voltage direct current circuit breaker as claimed in claim 1, characterized in that, in the test circuit built in the first step, the accumulated set of each IGBT device in the auxiliary flow valve The maximum repeatable peak current of the electrode reaches at least the rated current of the hybrid high-voltage direct current circuit breaker.

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