CN118646253A - Commutation failure warning method and system considering dynamic changes of large disturbance amplitude and frequency - Google Patents

Abstract

The present invention belongs to the field of safety control of direct current transmission systems, and provides a commutation failure warning method and system taking into account the dynamic changes of amplitude and frequency under large disturbances. A high-order regression model is used to represent the dynamic changes of amplitude and frequency of the commutation voltage; the actual measurement parameters of the amplitude and frequency of the commutation voltage are obtained, and the advance trigger time and zero-crossing time are calculated according to the set advance trigger angle and zero-crossing angle; based on the calculation results, an analytical calculation formula for the commutation area taking into account the dynamic changes of the amplitude and frequency of the commutation voltage is constructed, and the available turn-off time is solved to perform a commutation failure warning. The present invention can realize the accurate calculation of the available turn-off time of the thyristor during the commutation process, taking into account the influence of the dynamic changes of the commutation voltage after a large disturbance in the power system, and more accurately predict, control and analyze the LCC-HVDC commutation failure.

Description

Commutation failure warning method and system considering dynamic changes of large disturbance amplitude and frequency

Technical Field

The present invention belongs to the field of safety control of direct current power transmission systems, and in particular relates to a commutation failure early warning method and system taking into account dynamic changes in amplitude and frequency of large disturbances.

Background Art

The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

The lack of self-shutdown capability of thyristors is the root cause of commutation failure in line-commutated converter high voltage direct current (LCC-HVDC). The key quantitative indicator for evaluating commutation failure is whether the available off-time of the thyristor is greater than the required off-time. For the convenience of practical application, the off-time is usually converted into the arc extinction angle (expressed as ). The turn-off time required for the thyristor to turn off is typically 400 microseconds, corresponding to a minimum required arc extinction angle of 7.2° for a 50 Hz system and 8.64° for a 60 Hz system in steady state conditions.

Arc extinction angle By leading firing angle and commutation overlap angle Joint decision, i.e. The arc extinction angle is usually calculated based on the commutation area theory. The specific process is that according to Kirchhoff's voltage law, the commutation process satisfies the voltage-time area equation. Based on the voltage-time area equation, the arc extinction angle can be directly deduced. The analytical formula of has been widely used in the early warning and prevention of commutation failure in past studies.

However, with the large-scale access of high-proportion renewable energy generation to the power system, the system inertia is reduced, and the commutation voltage amplitude and frequency will enter a dynamic change process after a large disturbance. The required arc extinction angle is no longer a fixed value, and the analytical formula applicable to the steady state proposed in previous studies cannot be used to obtain an accurate value. Therefore, the arc extinction angle of the commutation process cannot be used as an equivalent quantitative indicator of the shutdown time. The only effective way to judge the commutation failure in dynamic scenarios is to directly and accurately calculate the available shutdown time.

Summary of the invention

In order to solve the above problems, the present invention proposes a commutation failure warning method and system taking into account the dynamic changes of large disturbance amplitude and frequency. The present invention can realize the accurate calculation of the available off-time of thyristors during the commutation process, consider the influence of the dynamic changes of commutation voltage after large disturbances in the power system, and more accurately predict, control and analyze LCC-HVDC commutation failure.

According to some embodiments, the present invention adopts the following technical solutions:

A commutation failure early warning method taking into account the dynamic change of large disturbance amplitude and frequency comprises the following steps:

A high-order regression model is used to represent the dynamic changes of the amplitude and frequency of the commutation voltage.

Obtain the actual measurement parameters of the amplitude and frequency of the commutation voltage, and calculate the advance trigger time and zero crossing time according to the set advance trigger angle and zero crossing angle;

Based on the calculation results, an analytical calculation formula for the commutation area considering the dynamic changes of the commutation voltage amplitude and frequency is constructed, and the available off-time is solved to provide a commutation failure warning.

As an optional implementation, the specific process of using a high-order regression model to represent the dynamic changes in amplitude and frequency of the commutation voltage includes: representing the commutation voltage waveform taking into account the time-varying amplitude and frequency, using a high-order regression model to represent the time-varying amplitude of the commutation voltage, using a high-order regression model to represent the time-varying phase of the commutation voltage, and then using a high-order regression model to represent the phasor at any time.

As a further implementation, the commutation voltage waveform considering the time-varying amplitude and frequency is expressed as:

In the formula, represent The phasor of time, yes The conjugated form of

In the formula, represents the time-varying amplitude of the commutation voltage, represents the center frequency, represents the initial phase angle, Represents the time-varying phase of the commutation voltage.

As a further implementation, the specific process of using a high-order regression model to represent the time-varying amplitude of the commutation voltage, using a high-order regression model to represent the time-varying phase of the commutation voltage, and then using a high-order regression model to represent the phasor at any time includes: and Expressed as a high-order regression model:

in, and represent the regression order of amplitude and frequency respectively, is the magnitude of The regression parameters, is the frequency Secondary regression parameters; and It can be expressed as a high-order regression model:

in and They are and No. The regression parameters are is a configuration parameter, and its value should not be less than and .

As a further implementation, according to the set advance trigger angle and zero-crossing angle, the specific process of calculating the advance trigger time and the zero-crossing time includes:

Construct the equation:

by , Newton iteration is performed for the initial value, and the correction formula for the i -th Newton iteration is , ,in, express The first-order derivative of , When it no longer changes, stop iterating and output , ;

in, represents the center frequency, represents the initial phase angle, represents the time-varying phase of the commutation voltage, To advance the trigger time, is the zero crossing time, is the leading firing angle, is the zero crossing angle.

As a further implementation method, based on the calculation results, the specific process of constructing the analytical calculation formula of the commutation area considering the dynamic change of the commutation voltage amplitude and frequency includes: constructing the equation ,in, is the commutation area required for the commutation process, is the analytical calculation formula for the commutation area, is the advance trigger time, where:

;

in, represents the center frequency, To advance the trigger time, and They are and No. The regression parameters are Not less than and , represent The phasor of time, yes conjugated form of .

As a further implementation method, the specific process of solving the available off-time and performing commutation failure warning includes:

by Newton iteration is performed for the initial value, and the correction formula for the i -th Newton iteration is ,in, express The first-order derivative of When it no longer changes, stop iterating and output ;

calculate ;

if , then the warning of commutation failure is given, where: is the minimum required off time, is the zero crossing time, represents the initial phase angle, is the zero crossing angle, The arc extinction time.

A commutation failure warning system taking into account dynamic changes in amplitude and frequency of large disturbances, comprising:

A modeling module is configured to use a high-order regression model to represent the amplitude-frequency dynamic changes of the commutation voltage;

A calculation module is configured to obtain actual measurement parameters of the amplitude and frequency of the commutation voltage, and calculate the advance trigger time and the zero crossing time according to the set advance trigger angle and the zero crossing angle;

The commutation failure warning module is configured to construct an analytical calculation formula for the commutation area taking into account the dynamic changes in the commutation voltage amplitude and frequency based on the calculation results, and solve the available off-time to issue a commutation failure warning.

A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the steps in the above method are completed.

An electronic device comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps in the above method are completed.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention adopts a high-order regression model to represent the dynamic change of the amplitude and frequency of the commutation voltage, without the need to obtain the specific change form of the amplitude and frequency a priori; then, according to the set leading trigger angle Zero crossing angle , calculate the advance trigger time and zero crossing time ; Further, based on the analytical calculation formula of the commutation area considering the dynamic change of the commutation voltage amplitude and frequency, the available off time is solved , realizing commutation failure warning; the present invention takes into account the influence of dynamic changes of commutation voltage after a large disturbance in the power system, and more accurately predicts, controls and analyzes LCC-HVDC commutation failure.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

FIG1 is a schematic diagram of a method flow chart of an embodiment.

DETAILED DESCRIPTION

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

It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and/or combinations thereof.

In the absence of conflict, the embodiments in this application and the features in the embodiments may be combined with each other.

Embodiment 1

The commutation failure warning method taking into account the dynamic change of amplitude and frequency of large disturbances is shown in Figure 1, including using a high-order regression model to represent the dynamic change of amplitude and frequency of the commutation voltage, without the need to obtain the specific change form of amplitude and frequency a priori; then according to the set advance trigger angle Zero crossing angle , calculate the advance trigger time and zero crossing time ; Further, based on the analytical calculation formula of the commutation area considering the dynamic change of the commutation voltage amplitude and frequency, the available off time is solved , realizing commutation failure warning.

The following are the steps as follows:

The commutation voltage waveform considering the time-varying amplitude and frequency is expressed as:

(1)

In the formula, represent The phasor of time, yes conjugated form of .

(2)

In the formula, represents the time-varying amplitude of the commutation voltage, represents the center frequency, represents the initial phase angle, represents the time-varying phase of the commutation voltage. Further, and Expressed as a high-order regression model:

(3)

(4)

in, and represent the regression order of amplitude and frequency respectively, is the magnitude of The regression parameters, is the frequency Secondary regression parameters. and It can be further expressed as a high-order regression model:

(5)

in and They are and No. The regression parameters are Not less than and .

Next, get , , , , Other measurement data, and , , And other measurement configuration parameters.

calculate and , specifically:

1) Construct equation:

(6)

2) , Newton iteration is performed for the initial value. The correction formula for the i -th Newton iteration is: , ,in, express The first derivative of . , When it no longer changes, stop iterating and output , .

Calculate arc extinction time and available off time , specifically:

1) Construct equation ,in, is the commutation area required for the commutation process, It is the analytical calculation formula for the commutation area.

(7)

2) Newton iteration is performed for the initial value. The correction formula for the i -th Newton iteration is: ,in, express The first derivative of . When it no longer changes, stop iterating and output .

3) .

4) If , then the warning of commutation failure is given. Among them, is the minimum required off time.

Embodiment 2

A commutation failure warning system taking into account dynamic changes in amplitude and frequency of large disturbances, comprising:

A modeling module is configured to use a high-order regression model to represent the amplitude-frequency dynamic changes of the commutation voltage;

A calculation module is configured to obtain actual measurement parameters of the amplitude and frequency of the commutation voltage, and calculate the advance trigger time and the zero crossing time according to the set advance trigger angle and the zero crossing angle;

The commutation failure warning module is configured to construct an analytical calculation formula for the commutation area taking into account the dynamic changes in the commutation voltage amplitude and frequency based on the calculation results, and solve the available off-time to issue a commutation failure warning.

It should be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD - ROM , optical storage, etc.) containing computer-usable program code.

The present invention is described with reference to the flowcharts and/or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and/or box in the flowchart and/or block diagram, as well as the combination of the processes and/or boxes in the flowchart and/or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present invention without creative labor shall be included in the protection scope of the present invention.

Claims (10)

1. A commutation failure early warning method taking into account the dynamic change of large disturbance amplitude and frequency, characterized in that it comprises the following steps: A high-order regression model is used to represent the dynamic changes of the amplitude and frequency of the commutation voltage. Obtain the actual measurement parameters of the amplitude and frequency of the commutation voltage, and calculate the advance trigger time and zero crossing time according to the set advance trigger angle and zero crossing angle; Based on the calculation results, an analytical calculation formula for the commutation area considering the dynamic changes of the commutation voltage amplitude and frequency is constructed, and the available off-time is solved to provide a commutation failure warning. 2. A commutation failure warning method taking into account the dynamic changes of large disturbance amplitude and frequency as described in claim 1 is characterized in that the specific process of using a high-order regression model to represent the dynamic changes of amplitude and frequency of the commutation voltage includes: representing the commutation voltage waveform considering the time-varying amplitude and frequency, using a high-order regression model to represent the time-varying amplitude of the commutation voltage, using a high-order regression model to represent the time-varying phase of the commutation voltage, and then using a high-order regression model to represent the phasor at any time. 3. A commutation failure warning method taking into account the dynamic change of large disturbance amplitude and frequency as claimed in claim 2, characterized in that the commutation voltage waveform considering the time-varying amplitude and frequency is expressed as: ; In the formula, represent The phasor of time, yes The conjugated form of ; ; In the formula, represents the time-varying amplitude of the commutation voltage, represents the center frequency, represents the initial phase angle, Represents the time-varying phase of the commutation voltage. 4. A commutation failure warning method taking into account the dynamic change of large disturbance amplitude and frequency as claimed in claim 3, characterized in that the specific process of using a high-order regression model to represent the time-varying amplitude of the commutation voltage, using a high-order regression model to represent the time-varying phase of the commutation voltage, and then using a high-order regression model to represent the phasor at any time includes: and Expressed as a high-order regression model: ; ; in, and represent the regression order of amplitude and frequency respectively, is the magnitude of The regression parameters, is the frequency Secondary regression parameters; and It can be expressed as a high-order regression model: ; in and They are and No. The regression parameters are is a configuration parameter, and its value should not be less than and . 5. A commutation failure warning method taking into account the dynamic change of large disturbance amplitude and frequency as claimed in claim 1, characterized in that the specific process of calculating the advance trigger time and the zero crossing time according to the set advance trigger angle and the zero crossing angle comprises: Construct the equation: ; by , Newton iteration is performed for the initial value, and the correction formula for the i -th Newton iteration is , ,in, express The first-order derivative of , When it no longer changes, stop iterating and output , ; in, represents the center frequency, represents the initial phase angle, represents the time-varying phase of the commutation voltage, To advance the trigger time, is the zero crossing time, is the leading firing angle, is the zero crossing angle. 6. A commutation failure warning method taking into account the dynamic change of large disturbance amplitude and frequency as claimed in claim 1, characterized in that, based on the calculation results, the specific process of constructing the commutation area analytical calculation formula taking into account the dynamic change of commutation voltage amplitude and frequency comprises: constructing equation ,in, is the commutation area required for the commutation process, is the analytical calculation formula for the commutation area, is the advance trigger time, where: ; in, represents the center frequency, To advance the trigger time, and They are and No. The regression parameters are Not less than and , represent The phasor of time, yes conjugated form of . 7. A commutation failure warning method taking into account the dynamic change of large disturbance amplitude and frequency as claimed in claim 6, characterized in that the specific process of solving the available off-time and performing commutation failure warning includes: by Newton iteration is performed for the initial value, and the correction formula for the i -th Newton iteration is ,in, express The first-order derivative of When it no longer changes, stop iterating and output ; calculate ; if , then the warning of commutation failure is given, where: is the minimum required off time, is the zero crossing time, represents the initial phase angle, is the zero crossing angle, The arc extinction time. 8. A commutation failure warning system taking into account the dynamic change of large disturbance amplitude and frequency, characterized in that it includes: A modeling module is configured to use a high-order regression model to represent the amplitude-frequency dynamic changes of the commutation voltage; A calculation module is configured to obtain actual measurement parameters of the amplitude and frequency of the commutation voltage, and calculate the advance trigger time and the zero crossing time according to the set advance trigger angle and the zero crossing angle; The commutation failure warning module is configured to construct an analytical calculation formula for the commutation area taking into account the dynamic changes in the commutation voltage amplitude and frequency based on the calculation results, and solve the available off-time to issue a commutation failure warning. 9. A computer-readable storage medium, characterized in that it is used to store computer instructions, and when the computer instructions are executed by a processor, the steps in the method according to any one of claims 1 to 7 are completed. 10. An electronic device, characterized in that it comprises a memory and a processor and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the steps in any one of the methods of claims 1-7 are completed.