Active detection protection orthogonal control method based on SVPWM

Abstract

The present invention relates to the technical field of relay protection for power systems, and provides an orthogonal control method for active detection protection based on SVPWM, comprising: controlling power electronic equipment using a control system employing SVPWM as a basic control system; providing a superimposed control system on the basis of the basic control system; and receiving, processing, and outputting signals orthogonal to the signals of the basic control system. The present invention actively generates detection signals during a fault period for power electronic equipment in a power system employing SVPWM, superimposes an additional control system on the basic control system, and receives, processes, and outputs signals orthogonal to the signals of the basic control system. Both the basic control system and the superimposed control system receive a measurement signal. The output of the basic control system and the output of the superimposed control system are added together to form the output of the new control system. Due to orthogonality, the signals received, processed, and output by the superimposed control system do not affect the signals of the basic control system.

Description

Technical Field

[0001] The present invention relates to the technical field of power system relay protection, and in particular to an active detection protection orthogonal control method based on SVPWM. Background Art

[0002] New power systems, including those integrating power generation, grid loading, and storage, will incorporate a large number of converters. The converter's vulnerability and the nonlinear, time-varying nature of fault processes place higher demands on the speed and reliability of relay protection, while also impacting the reliability of fault identification. The widespread use of power electronics in power systems has made traditional fault analysis methods and relay protection technologies difficult to apply.

[0003] Specifically, traditional fault analysis methods and relay protection technologies have the following problems:

[0004] 1. Power electronic equipment is widely used in power systems. When a short-circuit fault occurs, the fault current is limited, the fault characteristics are not obvious, and there are nonlinear time-varying characteristics. Traditional relay protection is insufficient in sensitivity, reliability, and speed.

[0005] 2. Active detection protection requires close coordination with the converter control system. On the one hand, under the existing structure and control mode, the control system may not be able to generate the specific signals required by the active detection protection algorithm. On the other hand, the injection signals used for active detection protection may interfere with the normal operation of the existing control system.

[0006] 3. After a short-circuit fault occurs, it cannot be quickly and reliably removed, affecting the safe and stable operation of the primary power system. Summary of the Invention

[0007] The purpose of the present invention is to solve at least one technical problem in the background technology and provide an active detection protection orthogonal control method based on SVPWM.

[0008] To achieve the above object, the present invention provides an active detection protection orthogonal control method based on SVPWM, comprising:

[0009] The control system uses SVPWM as the basis for controlling power electronic equipment;

[0010] Set up a superimposed control system based on the basic control system;

[0011] The signals received, processed and output by the superimposed control system are orthogonal to the signals of the basic control system.

[0012] According to one aspect of the present invention, the superposition control system controls the switching state of the converter device, tracks the space vector, and outputs the required waveform at the port.

[0013] According to one aspect of the present invention, the superposition control system is based on a negative sequence component or a zero sequence component.

[0014] According to one aspect of the present invention, when the superposition control system is based on the negative sequence component, the space vector V of the three-phase voltage of the negative sequence SVPWM sn for: The positive transformation S of the negative sequence dq transformation is:

[0015]

[0016] Inverse transform S -1 for:

[0017]

[0018] According to one aspect of the present invention, when the superposition control system is based on the zero-sequence component, the space vector V of the three-phase voltage of the zero-sequence SVPWM is s0 for:

[0019] According to the solution of the present invention, for power electronic equipment in a power system that uses a space vector pulse width modulation algorithm (SVPWM) for control, the present invention uses SVPWM as the basic control system, actively generates detection signals during a fault, and superimposes an additional control system on the basic control system. The signals received, processed, and output by the superimposed control system are orthogonal to the signals of the basic control system. Both the basic control system and the superimposed control system receive measurement signals from the primary system. The output of the basic control system and the output of the superimposed control system are added together to form the output of the new control system. Due to orthogonality, the signals received, processed, and output by the superimposed control system do not affect the signals of the basic control system.

[0020] According to the solution of the present invention, the present invention targets power systems where power electronic equipment is widely used. When a short circuit fault occurs, an active detection signal is injected through an additional control strategy to make the fault characteristics clearer and more specific.

[0021] The present invention uses an orthogonal control method to ensure that the additional control strategy and the original control strategy do not affect each other, thereby reducing the impact of active detection signals on the primary system;

[0022] In the present invention, clear and specific fault characteristics can construct a simpler, more sensitive and reliable protection principle, thereby improving the performance of traditional relay protection;

[0023] In the present invention, the short-circuit fault can be quickly removed, reducing the impact of the fault on the primary system, thereby improving the operational stability of the power system.

[0024] According to the solution of the present invention, the present invention provides an orthogonal control method for active detection protection based on SVPWM. First, by utilizing the controllability of power electronic equipment, a detection signal is actively generated during the fault period, and a clearer and more specific fault feature is injected, thereby improving the sensitivity and reliability of the protection by examining the response of the system to the detection signal. Secondly, in order to reduce the impact of the additional control system of the active detection signal on the original control system, an orthogonal control method is proposed, so that the control signals processed by the additional control strategy and the original control strategy are orthogonal, achieving the goal of the additional control strategy and the original control strategy not affecting each other, and reducing the impact on the primary system. Finally, the active detection signal has the characteristics of short duration and obvious fault characteristics. The present invention can quickly and reliably identify and eliminate the fault, reducing the impact of the fault on the primary system.

[0025] According to the solution of the present invention, the present invention provides a simple and clear characteristic signal to assist in the judgment of active detection relay protection; the present invention designs an additional control system that is easy to implement, reduces changes to the original control system, and reduces the impact on the original control system; the present invention reduces the impact on traditional protection algorithms, reduces the impact on the primary system, and reduces the impact on the primary system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flowchart schematically illustrates an active detection protection orthogonal control method based on SVPWM according to an embodiment of the present invention;

[0027] Figure 2 This is a typical converter circuit diagram using space vector pulse width modulation (SVPWM) control algorithm;

[0028] Figure 3 Schematic diagram of an orthogonal control system according to an embodiment of the present invention;

[0029] Figure 4 Schematic diagram of a superimposed negative sequence control system according to embodiment 1 of the present invention;

[0030] Figure 5 Schematic diagram of a superimposed zero-sequence control system according to embodiment 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only intended to enable those skilled in the art to better understand and implement the present invention, rather than to imply any limitation on the scope of the present invention.

[0032] As used herein, the term "including" and variations thereof are to be interpreted as open-ended terms meaning "including, but not limited to." The term "based on" is to be interpreted as "based, at least in part, on." The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment."

[0033] Figure 1 The flowchart of the active detection protection orthogonal control method based on SVPWM according to one embodiment of the present invention is schematically shown. Figure 1 As shown, in this embodiment, the active detection protection orthogonal control method based on SVPWM is characterized by including:

[0034] a. Based on the control system using SVPWM, the control system controls the power electronic equipment;

[0035] b. Set up a superimposed control system based on the basic control system;

[0036] c. The signals received, processed and output by the superimposed control system are orthogonal to the signals of the basic control system.

[0037] In this embodiment, the superposition control system controls the switching state of the converter device, tracks the space vector, and outputs the required waveform at the port.

[0038] In this embodiment, the superposition control system is based on the negative sequence component or the zero sequence component.

[0039] In this embodiment, when the superposition control system is based on the negative sequence component, the space vector V of the three-phase voltage of the negative sequence SVPWM is sn for: The positive transformation S of the negative sequence dq transformation is:

[0040]

[0041] Inverse transform S -1 for:

[0042]

[0043] In this embodiment, when the superposition control system is based on the zero-sequence component, the space vector V of the three-phase voltage of the zero-sequence SVPWM is s0 for:

[0044] According to the above-mentioned solution of the present invention, for power electronic equipment in a power system that uses a space vector pulse width modulation algorithm (SVPWM) for control, the present invention uses SVPWM as the basic control system, actively generates detection signals during a fault, and superimposes an additional control system on the basic control system. The signals received, processed, and output by the superimposed control system are orthogonal to the signals of the basic control system. Both the basic control system and the superimposed control system receive the measurement signal of the primary system. The output of the basic control system and the output of the superimposed control system are added together to form the output of the new control system. Due to orthogonality, the signals received, processed, and output by the superimposed control system do not affect the signals of the basic control system.

[0045] According to the above solution of the present invention, the present invention is aimed at power systems where power electronic equipment is widely used. When a short circuit fault occurs, an active detection signal is injected through an additional control strategy to make the fault characteristics clearer and more specific.

[0046] The present invention uses an orthogonal control method to ensure that the additional control strategy and the original control strategy do not affect each other, thereby reducing the impact of active detection signals on the primary system;

[0047] In the present invention, clear and specific fault characteristics can construct a simpler, more sensitive and reliable protection principle, thereby improving the performance of traditional relay protection;

[0048] In the present invention, the short-circuit fault can be quickly removed, reducing the impact of the fault on the primary system, thereby improving the operational stability of the power system.

[0049] Based on the above solutions of the present invention, the solutions of the present invention are described in detail below in the form of specific embodiments in conjunction with the accompanying drawings.

[0050] Example 1

[0051] Figure 2 The following is a typical converter circuit diagram using the space vector pulse width modulation algorithm (SVPWM) control. For power electronic equipment using SVPWM control in power systems, SVPWM is used as the basic control system. When a disturbance is detected in the system, a detection signal is actively generated. A superimposed control system is set up on the basis of the basic control system. The signals received, processed and output by the superimposed control system are orthogonal to the signals of the basic control system. Figure 3 shown.

[0052] SVPWM converts the three-phase voltage u with a phase difference of 120° on the complex plane into a 、u b and u c Resultant space vector V s , space vector V s for:

[0053]

[0054] The control method of the superposition control system is to control the switching state of the converter device for a given control signal, track the space vector, and output the required waveform at the port.

[0055] The definition of the space vector is essentially to obtain the positive sequence voltage. The control and calculation based on this are all based on the positive sequence voltage component and will not affect the negative sequence and zero sequence components.

[0056] The superposition control system is constructed based on the negative sequence component, such as Figure 4 shown.

[0057] Using negative sequence SVPWM, the three-phase voltage space vector V sn for

[0058]

[0059] For any measurement signal, its positive-sequence power frequency component will only affect the basic control system, and its negative-sequence power frequency component will only affect the superimposed control system.

[0060] Negative sequence SVPWM needs to adopt negative sequence dq transformation in the specific control system. The positive transformation S of negative sequence dq transformation is:

[0061]

[0062] The corresponding inverse transform S -1 for:

[0063]

[0064] Both the base control system and the superimposed control system receive the measurement signals from the primary system. The output of the base control system and the output of the superimposed control system are added together to form the output of the new control system. Due to orthogonality, the signals received, processed, and output by the superimposed control system do not affect the signals of the base control system.

[0065] Example 2

[0066] Figure 2 The following is a typical converter circuit diagram using the space vector pulse width modulation algorithm (SVPWM) control. For power electronic equipment using SVPWM control in power systems, SVPWM is used as the basic control system. When a disturbance is detected in the system, a detection signal is actively generated. A superimposed control system is set up on the basis of the basic control system. The signals received, processed and output by the superimposed control system are orthogonal to the signals of the basic control system. Figure 3 shown.

[0067] SVPWM converts the three-phase voltage u with a phase difference of 120° on the complex plane into a 、u b and u c Resultant space vector V s , the space vector V is:

[0068]

[0069] The control method of the superposition control system is to control the switching state of the converter device for a given control signal, track the space vector, and output the required waveform at the port.

[0070] The definition of the space vector is essentially to obtain the positive sequence voltage. The control and calculation based on this are all based on the positive sequence voltage component and will not affect the negative sequence and zero sequence components.

[0071] Different from Example 1, the superposition control system is constructed based on the zero-sequence component, such as Figure 5 shown.

[0072] The space vector V of the three-phase voltage of zero-sequence SVPWM s0 for:

[0073]

[0074] For any measurement signal, its positive-sequence power frequency component only affects the basic control system, and its zero-sequence power frequency component only affects the superposition control system. Since zero-sequence SVPWM is the usual zero-sequence transformation, there is no need to design a new dq transformation.

[0075] Both the base control system and the superimposed control system receive the measurement signals from the primary system. The output of the base control system and the output of the superimposed control system are added together to form the output of the new control system. Due to orthogonality, the signals received, processed, and output by the superimposed control system do not affect the signals of the base control system.

[0076] According to the above scheme of the present invention, the present invention provides an orthogonal control method for active detection protection based on SVPWM. First, by utilizing the controllability of power electronic equipment, a detection signal is actively generated during the fault period, and a clearer and more specific fault feature is injected, thereby improving the sensitivity and reliability of the protection by examining the response of the system to the detection signal. Secondly, in order to reduce the impact of the additional control system of the active detection signal on the original control system, an orthogonal control method is proposed, so that the control signals processed by the additional control strategy and the original control strategy are orthogonal, achieving the goal of the additional control strategy and the original control strategy not affecting each other, and reducing the impact on the primary system. Finally, the active detection signal has the characteristics of short duration and obvious fault characteristics. The present invention can quickly and reliably identify and eliminate the fault, reducing the impact of the fault on the primary system.

[0077] According to the above-mentioned scheme of the present invention, the present invention provides a simple and clear characteristic signal to assist in the judgment of active detection relay protection; the present invention designs an additional control system that is easy to implement, reduces the changes to the original control system, and reduces the impact on the original control system; the present invention reduces the impact on traditional protection algorithms, reduces the impact on the primary system, and reduces the impact on the primary system.

[0078] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. The active detection protection orthogonal control method based on SVPWM is characterized by: include: The control system uses SVPWM as the basis for controlling power electronic equipment; Set up a superimposed control system based on the basic control system; The signals received, processed and output by the superimposed control system are orthogonal to the signals of the basic control system; The superposition control system controls the switching state of the converter device, tracks the space vector, and outputs the required waveform at the port; The superposition control system is based on the negative sequence component or the zero sequence component; When the superposition control system is based on the negative sequence component, the space vector of the three-phase voltage of the negative sequence SVPWM for: , the positive transformation S of the negative sequence dq transformation is: ； Inverse Transform for: ； When the superposition control system is based on the zero-sequence component, the space vector of the three-phase voltage of the zero-sequence SVPWM for: .

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