CN115133509A - Method and device for judging fault phase of converter control system with series compensation device - Google Patents

Abstract

The application discloses a method and a device for judging fault phases of a converter control system with a series compensation device, wherein the method comprises the following steps: injecting a high-frequency harmonic signal into a converter control system to be tested; extracting harmonic current at the protection installation position of a converter control system to be tested, and extracting a positive sequence component, a negative sequence component and a zero sequence component of the harmonic current; and judging the fault phase by combining preset phase selection criteria according to the amplitudes and phase differences of the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current. According to the method, the harmonic current at the protective installation position is extracted through the injection of the harmonic signal and the FFT algorithm, and the fault phase selection is carried out by utilizing the phase relation of the harmonic current sequence component. The capacitance reactance of the series compensation capacitor is reduced along with the increase of the frequency, and the line impedance and the synchronous machine impedance are increased along with the increase of the frequency, so that the fault phase judging method provided by the application has good performance in a system with a series compensation device.

Description

Method and device for judging fault phase of inverter control system with series compensation device

technical field

The present application relates to the technical field of relay protection, and in particular, to a method and device for judging fault phases of an inverter control system including a series compensation device.

Background technique

At present, my country's large-capacity new energy stations, such as photovoltaic power stations and wind farms, are mostly located in remote western areas. In order to improve the transmission capacity of the stations, series compensation devices (series compensation devices) are often installed at the end of their transmission lines. However, the traditional protection principle relies on the sequence impedance characteristics of the system, which is different from the equivalent sequence impedance phase of the transmission line and the synchronous machine, which is approximately 90°. There may be adaptability issues in the system.

At present, the research on the impact of series compensation devices on traditional protection mainly focuses on distance protection. Among them, some studies pointed out that the capacity of the series compensation device may lead to the phenomenon of "transient overrun" based on the power frequency distance protection. However, there is no prior art that studies the influence of the connection of the series compensation device on the phase selection element. In practical applications, whether it is a sequence current phase selection element or a sequence voltage phase selection element, the protection principle depends on the feature that the phase of the sequence impedance of the system element is approximately 90°. This feature is broken when there is a string compensation device in the system. Therefore, when the traditional phase selection element includes a series compensation device, it is easy to misjudge the normal phase of the system as a faulty phase. A solution for this situation has not yet emerged.

SUMMARY OF THE INVENTION

The purpose of this application is to provide a method and device for judging the fault phase of an inverter control system including a series compensation device, so as to solve the problem that the performance of the phase selection element in the existing inverter control system including a series compensation device is degraded, and even easy to A phase selection failure occurred.

In order to achieve the above purpose, the present application provides a method for judging the fault phase of an inverter control system including a series compensation device, including:

Inject high-frequency harmonic signals into the control system of the converter under test;

Extract the harmonic current at the protection installation of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current;

According to the amplitudes of the positive, negative and zero sequence components of the harmonic current and the phase difference between them, combined with the preset phase selection criteria, the faulty phase is judged.

Further, preferably, according to the amplitude of the positive-sequence component, the negative-sequence component and the zero-sequence component of the harmonic current and the phase difference between the two, in combination with the preset phase selection criterion to determine the faulty phase, including:

及

Denote the positive, negative and zero sequence components of the harmonic current as

and

和

的幅值均小于

的5％时，则判定故障类型为三相对称故障；when

and

amplitudes are less than

5%, it is judged that the fault type is a three-phase symmetrical fault;

的幅值小于

且

幅值大于

时，则判定故障类型为第一相间故障；when

magnitude is less than

and

Amplitude greater than

, the fault type is determined to be the first phase-to-phase fault;

的幅值和

的幅值均大于

时，则判定故障类型为单相故障或第二相间故障。when

The magnitude of and

amplitudes are greater than

, the fault type is determined to be a single-phase fault or a second-phase fault.

Further, preferably, the described method for judging the fault phase of the inverter control system containing the series compensation device further includes:

和

的相位差：When the fault type is the first phase-to-phase fault, calculate

and

The phase difference of:

则判定故障类型为BC故障；like

Then it is judged that the fault type is BC fault;

则判定故障类型为CA故障；like

Then it is judged that the fault type is CA fault;

则判定故障类型为AB故障；like

Then it is judged that the fault type is AB fault;

和

和

的相位差：When the fault type is single-phase fault or second-phase fault, calculate

and

and

The phase difference of:

且

则判定故障类型为AG故障；like

and

Then it is judged that the fault type is AG fault;

且

则判定故障类型为BCG故障；like

and

Then it is judged that the fault type is BCG fault;

且

则判定故障类型为BG故障；like

and

Then it is determined that the fault type is BG fault;

且

则判定故障类型为CAG故障；like

and

Then it is judged that the fault type is CAG fault;

且

则判定故障类型为CG故障；like

and

Then it is judged that the fault type is CG fault;

且

则判定故障类型为ABG故障。like

and

Then it is determined that the fault type is ABG fault.

Further, preferably, the injection of high-frequency harmonic signals into the control system of the converter under test includes:

The harmonic electrical reference value is superimposed in the PWM link of the inverter control system to realize the injection of high-frequency harmonic signals.

Further, preferably, the described method for judging the fault phase of the inverter control system containing the series compensation device further includes:

The improved phase-locked loop is used to realize the decoupling control of the power frequency electrical quantity and the harmonic electrical quantity of the injected high-frequency harmonic signal in the converter control system; wherein, the high-frequency harmonic signal is a high-frequency high-order harmonic wave signal.

Further, preferably, a full-wave Fourier algorithm is used to extract the harmonic components of the harmonic current.

Further, preferably, the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current are extracted, including:

The positive-sequence, negative-sequence and zero-sequence components of harmonic currents are extracted by using Parker transform; among them, the Parker transform matrix C _Park is:

Among them, θ is the common point voltage phase calculated by the phase-locked loop.

The application also provides a fault-phase judging device for a converter control system including a series compensation device, including:

The high-frequency harmonic injection unit is used to inject high-frequency harmonic signals into the control system of the converter under test;

The harmonic component extraction unit is used to extract the harmonic current at the protection installation of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current;

The fault phase discrimination unit is used to discriminate the fault phase according to the amplitudes of the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current and the phase difference between them, combined with the preset phase selection criterion.

The application also provides a terminal device, including:

one or more processors;

a memory, coupled to the processor, for storing one or more programs;

When the one or more programs are executed by the one or more processors, the one or more processors implement the method for judging the fault phase of a converter control system including a series compensation device according to any one of the above .

The present application also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, realizes the fault phase discrimination of the inverter control system including the series compensation device according to any one of the above method.

Compared with the prior art, the beneficial effects of the present application are:

The present application comprehensively considers the characteristics of the fault sequence network with the series compensation system, the decoupling of the power frequency electrical quantity and the harmonic electrical quantity in the active harmonic injection control, and the influence of the harmonic frequency on the protection performance. Firstly, a control strategy that can inject harmonics into the power system is designed. Then, combined with the full fault network constructed by the harmonic components, the phase relationship of the sequence component of the current at the protection installation under different fault types is deduced, and the phase selection criterion is proposed. When the system fails, the fault phase selection can be realized by calculating the phase difference of the harmonic current sequence components at the protection installation.

The present application realizes the injection of harmonic signals by adjusting the control strategy of the converter, extracts the harmonic current at the protection installation through the FFT algorithm, and uses the phase relationship of the harmonic current sequence components for fault phase selection. Since the capacitive reactance of the series compensation capacitor decreases with the increase of the frequency, while the line impedance and the impedance of the synchronous machine increase with the increase of the frequency, the fault phase discrimination method of the present application has the advantages of the system including the series compensation device. good performance.

Description of drawings

In order to illustrate the technical solutions of the present application more clearly, the following briefly introduces the accompanying drawings used in the implementation manner. Obviously, the accompanying drawings in the following description are only some implementations of the present application, which are common in the art. As far as technical personnel are concerned, other drawings can also be obtained based on these drawings without any creative effort.

1 is a schematic flowchart of a method for judging a fault phase of a converter control system containing a series compensation device provided by an embodiment of the present application;

2 is a schematic diagram of a 175MW photovoltaic system built in PSCAD software provided by an embodiment of the present application;

3 is a control block diagram of active harmonic injection provided by an embodiment of the present application;

4 is a flowchart of a selected phase element provided by an embodiment of the present application;

5 is a schematic structural diagram of a device for judging fault phases in a converter control system including a series compensation device provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a terminal device provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

It should be understood that the step numbers used in the text are only for the convenience of description, and are not intended to limit the order in which the steps are performed.

It should be understood that the terms used in the specification of the present application are only for the purpose of describing particular embodiments and are not intended to limit the present application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly dictates otherwise.

The terms "comprising" and "comprising" indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or more other features, integers, steps, operations, elements, components and/or the existence or addition of its collection.

The term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

Referring to FIG. 1 , an embodiment of the present application provides a method for judging a fault phase of an inverter control system including a series compensation device. As shown in FIG. 1 , the method for judging a faulty phase of an inverter control system including a series compensation device includes steps S10 to S30 . The specific steps are as follows:

S10. Inject a high-frequency harmonic signal into the control system of the converter to be tested.

Please refer to Figure 2. Figure 2 provides a schematic diagram of a 175MW photovoltaic system built in PSCAD software, including a converter station system (converter control system) and a synchronous machine system. In this step, during the system failure, the harmonic voltage signal, that is, the harmonic electrical reference value, is superimposed on the Pulse Width Modulation (PWM, Pulse Width Modulation) link of the converter control system, so as to realize the injection of the high-frequency harmonic signal. .

分别为换流站公共点工频信号分量；上标*号代表对应分量的参考值；

和

代表工频电压正负序分量参考值；u_k代表所注入的谐波分量参考值。Further, Figure 3 presents a block diagram of the proposed active harmonic control, based on the control strategy shown in Figure 3, to inject harmonic signals into the converter control system during faults. in

are the power frequency signal components at the common point of the converter station respectively; the superscript * represents the reference value of the corresponding component;

and

Represents the reference value of the positive and negative sequence components of the power frequency voltage; u _k represents the reference value of the injected harmonic components.

In one embodiment, the improved phase-locked loop is used to realize the decoupling control of the power frequency electrical quantity and the harmonic electrical quantity of the injected high-frequency harmonic signal in the converter control system. Preferably, the high-frequency harmonic signal is a high-frequency high-order harmonic signal, thereby reducing the influence of the series compensation device in the line on the protection performance.

S20, extract the harmonic current at the protection installation location of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current.

In this step, a full-wave Fourier algorithm is used to extract the harmonic components of the harmonic current.

In a specific implementation manner, the system power frequency signal is 50 Hz and the injected harmonic signal is 200 Hz as an example. At this time, a time window of at least 20ms is required to accurately extract the 200Hz signal, and the full-wave Fourier (FFT) algorithm is used to extract it.

Further, the positive-sequence component, the negative-sequence component and the zero-sequence component of the harmonic current are extracted by using Parker transform; wherein, the Parker transform matrix C _Park is:

Among them, θ is the common point voltage phase calculated by the phase-locked loop.

S30 , according to the amplitudes of the positive-sequence component, the negative-sequence component and the zero-sequence component of the harmonic current and the phase difference between them, combined with a preset phase selection criterion to determine the faulty phase.

In this step, by comparing the amplitudes of the positive-sequence component, the negative-sequence component and the zero-sequence component, the phase difference is calculated, and the fault phase selection is completed in combination with the criterion. Its specific flowchart is shown in Figure 4, which specifically includes the following steps:

及

Denote the positive, negative and zero sequence components of the harmonic current as

and

和

的幅值均小于

的5％时，则判定故障类型为三相对称故障；when

and

amplitudes are less than

5%, it is judged that the fault type is a three-phase symmetrical fault;

的幅值小于

且

幅值大于

时，则判定故障类型为第一相间故障；when

magnitude is less than

and

Amplitude greater than

, the fault type is determined to be the first phase-to-phase fault;

的幅值和

的幅值均大于

时，则判定故障类型为单相故障或第二相间故障。when

The magnitude of and

amplitudes are greater than

, the fault type is determined to be a single-phase fault or a second-phase fault.

和

的相位差：In a specific embodiment, when the fault type is the first phase-to-phase fault, calculate

and

The phase difference of:

则判定故障类型为BC故障；like

Then it is judged that the fault type is BC fault;

则判定故障类型为CA故障；like

Then it is judged that the fault type is CA fault;

则判定故障类型为AB故障；like

Then it is judged that the fault type is AB fault;

和

和

的相位差：In a specific embodiment, when the fault type is a single-phase fault or a second-phase fault, calculate

and

and

The phase difference of:

且

则判定故障类型为AG故障；like

and

Then it is judged that the fault type is AG fault;

且

则判定故障类型为BCG故障；like

and

Then it is judged that the fault type is BCG fault;

且

则判定故障类型为BG故障；like

and

Then it is determined that the fault type is BG fault;

且

则判定故障类型为CAG故障；like

and

Then it is judged that the fault type is CAG fault;

且

则判定故障类型为CG故障；like

and

Then it is judged that the fault type is CG fault;

且

则判定故障类型为ABG故障。like

and

Then it is determined that the fault type is ABG fault.

To sum up, the method for judging the fault phase of a converter control system with a series compensation device provided by the embodiment of the present application realizes the injection of harmonic signals by adjusting the control strategy of the converter, and extracts the protection installation location by using the FFT algorithm. The phase relationship of the harmonic current sequence components is used to select the fault phase. Since the capacitive reactance of the series compensation capacitor decreases with the increase of the frequency, while the line impedance and the impedance of the synchronous machine increase with the increase of the frequency, the fault phase discrimination method of the present application has the advantages of the system including the series compensation device. good performance.

Please refer to FIG. 5. An embodiment of the present application also provides a fault phase discriminating device for a converter control system including a series compensation device, including:

The high-frequency harmonic injection unit 01 is used to inject high-frequency harmonic signals into the control system of the converter under test;

The harmonic component extraction unit 02 is used to extract the harmonic current at the protection installation place of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current;

The fault phase discrimination unit 03 is used for discriminating the fault phase according to the amplitude of the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current and the phase difference between them, combined with the preset phase selection criterion.

In one embodiment, the fault phase discriminating unit 03 is further used for:

及

Denote the positive, negative and zero sequence components of the harmonic current as

and

和

的幅值均小于

的5％时，则判定故障类型为三相对称故障；when

and

amplitudes are less than

5%, it is judged that the fault type is a three-phase symmetrical fault;

的幅值小于

且

幅值大于

时，则判定故障类型为第一相间故障；when

magnitude is less than

and

Amplitude greater than

, the fault type is determined to be the first phase-to-phase fault;

的幅值和

的幅值均大于

时，则判定故障类型为单相故障或第二相间故障。when

The magnitude of and

amplitudes are greater than

, the fault type is determined to be a single-phase fault or a second-phase fault.

和

的相位差：When the fault type is the first phase-to-phase fault, calculate

and

The phase difference of:

则判定故障类型为BC故障；like

Then it is judged that the fault type is BC fault;

则判定故障类型为CA故障；like

Then it is judged that the fault type is CA fault;

则判定故障类型为AB故障；like

Then it is judged that the fault type is AB fault;

和

和

的相位差：When the fault type is single-phase fault or second-phase fault, calculate

and

and

The phase difference of:

且

则判定故障类型为AG故障；like

and

Then it is judged that the fault type is AG fault;

且

则判定故障类型为BCG故障；like

and

Then it is judged that the fault type is BCG fault;

且

则判定故障类型为BG故障；like

and

Then it is determined that the fault type is BG fault;

且

则判定故障类型为CAG故障；like

and

Then it is judged that the fault type is CAG fault;

且

则判定故障类型为CG故障；like

and

Then it is judged that the fault type is CG fault;

且

则判定故障类型为ABG故障。like

and

Then it is determined that the fault type is ABG fault.

In one embodiment, the high-frequency harmonic injection unit 01 is further configured to superimpose the harmonic electrical reference value in the PWM link of the inverter control system, so as to realize the injection of the high-frequency harmonic signal.

In one embodiment, the high-frequency harmonic injection unit 01 is further configured to realize the decoupling of the power frequency electrical quantity and the harmonic electrical quantity of the injected high-frequency harmonic signal in the converter control system by using an improved phase-locked loop control; wherein, the high-frequency harmonic signal is a high-frequency high-order harmonic signal.

In one embodiment, the harmonic component extraction unit 02 is further configured to extract the harmonic component of the harmonic current by using a full-wave Fourier algorithm.

In one embodiment, the harmonic component extraction unit 02 is further configured to extract the positive-sequence component, negative-sequence component and zero-sequence component of the harmonic current by using Parker transform; wherein, the Parker transform matrix C _Park is:

Among them, θ is the common point voltage phase calculated by the phase-locked loop.

It can be understood that the fault phase discriminating device of the inverter control system including the series compensation device provided in the embodiment of the present application is used to execute the fault phase of the inverter control system including the series compensation device described in any of the above embodiments. Discrimination method, and achieve the same effect, and will not be further described here.

Referring to FIG. 6, an embodiment of the present application provides a terminal device, including:

one or more processors;

a memory, coupled to the processor, for storing one or more programs;

When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method for judging the fault phase of an inverter control system including a series compensation device.

The processor is used to control the overall operation of the terminal equipment, so as to complete all or part of the steps of the above-mentioned method for judging the fault phase of the inverter control system including the series compensation device. The memory is used to store various types of data to support operation at the terminal device, such data may include, for example, instructions for any application or method to operate on the terminal device, as well as application-related data. The memory can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM for short), Electrically Erasable Programmable Read-Only Memory (Electrically Erasable Programmable Read-Only Memory) Erasable Programmable Read-Only Memory (EEPROM for short), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (Read -Only Memory, referred to as ROM), magnetic memory, flash memory, magnetic disk or optical disk.

In an exemplary embodiment, the terminal device may be implemented by one or more Application Specific Integrated Circuits (AS1C for short), Digital Signal Processor (Digital Signal Processor, DSP for short), Digital Signal Processing (Digital Signal Processing) equipment Device, referred to as DSPD), Programmable Logic Device (Programmable Logic Device, referred to as PLD), Field Programmable Gate Array (Field Programmable Gate Array, referred to as FPGA), controller, microcontroller, microprocessor or other electronic components to achieve, The method for judging the fault phase of a converter control system including a series compensation device according to any one of the above embodiments is used, and the technical effect consistent with the above method is achieved.

In another exemplary embodiment, there is also provided a computer-readable storage medium comprising a computer program, when the computer program is executed by a processor, the converter including the series compensation device according to any one of the above embodiments is implemented The steps of the method for judging the fault phase of the control system. For example, the computer-readable storage medium can be the above-mentioned memory including a computer program, and the above-mentioned computer program can be executed by the processor of the terminal device to complete the fault of the inverter control system including the series compensation device according to any one of the above-mentioned embodiments. The phase discrimination method is adopted, and the technical effect consistent with the above method is achieved.

The above are the preferred embodiments of the present application. It should be pointed out that for those skilled in the art, without departing from the principles of the present application, several improvements and modifications can also be made, and these improvements and modifications may also be regarded as The protection scope of this application.

Claims (10)

1. a method for judging the fault phase of a converter control system containing a series compensation device, is characterized in that, comprising: injecting a high frequency harmonic signal into the converter control system to be tested; Extract the harmonic current at the protection installation of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current; According to the amplitudes of the positive, negative and zero sequence components of the harmonic current and the phase difference between them, combined with the preset phase selection criteria, the faulty phase is judged. 2 . The method for judging the fault phase of a converter control system containing a series compensation device according to claim 1 , wherein the amplitude and The phase difference between the two, combined with the preset phase selection criteria to determine the faulty phase, including: Denote the positive, negative and zero sequence components of the harmonic current as

and

when

and

amplitudes are less than

5%, it is judged that the fault type is a three-phase symmetrical fault; when

magnitude is less than

and

Amplitude greater than

, the fault type is determined to be the first phase-to-phase fault; when

The magnitude of and

amplitudes are greater than

, the fault type is determined to be a single-phase fault or a second-phase fault. 3. The method for judging the fault phase of an inverter control system containing a series compensation device according to claim 2, characterized in that, further comprising: When the fault type is the first phase-to-phase fault, calculate

and

The phase difference of: like

Then it is judged that the fault type is BC fault; like

Then it is judged that the fault type is CA fault; like

Then it is judged that the fault type is AB fault; When the fault type is single-phase fault or second-phase fault, calculate

and

and

The phase difference of: like

and

Then it is judged that the fault type is AG fault; like

and

Then it is judged that the fault type is BCG fault; like

and

Then it is determined that the fault type is BG fault; like

and

Then it is judged that the fault type is CAG fault; like

and

Then it is judged that the fault type is CG fault; like

and

Then it is determined that the fault type is ABG fault. 4. The method for judging the fault phase of a converter control system containing a series compensation device according to claim 1, wherein the injection of a high-frequency harmonic signal into the converter control system to be tested comprises: The harmonic electrical reference value is superimposed in the PWM link of the inverter control system to realize the injection of high-frequency harmonic signals. 5. The method for judging fault phases of an inverter control system containing a series compensation device according to claim 4, characterized in that, further comprising: The improved phase-locked loop is used to realize the decoupling control of the power frequency electrical quantity and the harmonic electrical quantity of the injected high-frequency harmonic signal in the converter control system; wherein, the high-frequency harmonic signal is a high-frequency high-order harmonic wave signal. 6 . The method for judging the fault phase of a converter control system with a series compensation device according to claim 1 , wherein the harmonic components of the harmonic current are extracted by using a full-wave Fourier algorithm. 7 . 7. The method for judging the fault phase of a converter control system containing a series compensation device according to claim 1, wherein the extraction of the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current comprises: The positive-sequence, negative-sequence and zero-sequence components of harmonic currents are extracted by using Parker transform; among them, the Parker transform matrix C _Park is:

Among them, θ is the common point voltage phase calculated by the phase-locked loop. 8. A device for judging fault phases of an inverter control system containing a series compensation device, characterized in that it comprises: The high-frequency harmonic injection unit is used to inject high-frequency harmonic signals into the control system of the converter under test; The harmonic component extraction unit is used to extract the harmonic current at the protection installation of the converter control system to be tested, and extract the positive sequence component, negative sequence component and zero sequence component of the harmonic current; The fault phase discrimination unit is used to discriminate the fault phase according to the amplitudes of the positive sequence component, the negative sequence component and the zero sequence component of the harmonic current and the phase difference between them, combined with the preset phase selection criterion. 9. A terminal device, comprising: one or more processors; a memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the inverter control including the series compensation device according to any one of claims 1-7 System fault identification method. 10. A computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a processor, the commutation containing the series compensation device according to any one of claims 1-7 is realized The method of judging the fault phase of the controller control system.

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