A method for quickly extracting positive and negative sequence components of a fundamental electrical physical quantity

Abstract

The application provides a method for quickly extracting positive and negative sequence components of a fundamental electrical physical quantity, comprising: collecting three-phase fundamental voltages in real time; determining a fundamental synthetic rotating vector in an alpha-beta coordinate system based on the three-phase fundamental voltages; constructing a positive and negative sequence operation matrix based on the fundamental synthetic rotating vector in the alpha-beta coordinate system; and extracting positive and negative sequence components based on the positive and negative sequence operation matrix. The method provided by the application breaks through the constraint of a fixed delay on the extraction time by flexibly configuring a delay parameter, effectively improves the adaptability and extraction flexibility of the delay method under different working conditions, and retains the inherent advantages of the delay method, such as simplicity and small calculation amount.

Description

Technical Field

[0001] This application relates to the field of power electronic converter control technology, and in particular to a method for rapidly extracting the positive and negative sequence components of fundamental electrical physical quantities. Background Technology

[0002] With the continuous advancement of energy conservation and emission reduction goals and the rapid construction of new power systems, distributed new energy equipment such as wind power, photovoltaics, and energy storage are being connected on a large scale. This has led to increasingly complex power system operating conditions, resulting in frequent power quality problems such as voltage sags, harmonic pollution, and three-phase imbalance. To ensure that power electronic converters can maintain uninterrupted and stable operation under fault conditions and effectively reduce converter fault current, the requirements for rapid and accurate extraction of fundamental electrical quantities have increased. Positive-sequence and negative-sequence components are the core basis for power grid fault diagnosis, converter control, power quality assessment, and relay protection actions. Their extraction speed and accuracy directly determine the effectiveness and reliability of upper-level control and protection strategies.

[0003] Currently, methods for extracting positive and negative sequence components mainly include frequency domain analysis methods based on Fourier transform and methods based on dq coordinate transformation. Methods based on Fourier transform extract the fundamental amplitude and phase through frequency domain analysis, and then calculate the positive and negative sequence components using symmetrical component analysis. However, these methods require integer-cycle data windows, have slow dynamic response speeds, and are difficult to meet the needs of rapidly changing transient processes. Furthermore, their accuracy decreases significantly under harmonic interference. Methods based on dq coordinate transformation obtain the synchronous phase through a phase-locked loop (PLL) and complete the positive and negative sequence separation in a rotating coordinate system, improving dynamic performance. However, they are sensitive to PLL parameter tuning, and the separation results are prone to cross-coupling when the grid frequency fluctuates or the voltage is asymmetrical, limiting their adaptability. In contrast, fundamental frequency positive and negative sequence extraction methods based on delay signal cancellation (DSC) have the advantages of simple principle, low computational load, and ease of implementation. The time-delay method based on 1 / 4 of the fundamental frequency period was the earliest and most widely used Orthogonal Signal Generation (OSG) method. While cascaded DSC can eliminate harmonic components of any order and negative sequence components, the delay time is relatively long. Existing time-delay methods use fixed delay parameters, making it difficult to arbitrarily configure the delay time as needed. This hinders the flexible selection of delay values ​​required for different operating conditions and limits the adaptability of positive and negative sequence component extraction. Summary of the Invention

[0004] This application provides a method for rapidly extracting the positive and negative sequence components of fundamental electrical physical quantities. To solve the above-mentioned technical problems, this application adopts the following technical method: This application provides a method for rapidly extracting the positive and negative sequence components of fundamental electrical physical quantities, including: Real-time acquisition of three-phase fundamental voltage; Based on the three-phase fundamental voltage, determine the fundamental wave synthesis rotation vector in the αβ coordinate system; Based on the fundamental wave synthesis rotation vector in the αβ coordinate system, construct the positive and negative order operation matrix; Based on the positive and negative order operation matrix, the positive and negative order components are extracted.

[0005] Optionally, determining the fundamental wave synthesis rotation vector in the αβ coordinate system based on the three-phase fundamental voltage includes: The three-phase fundamental voltages are subjected to Clark transformation to obtain the fundamental composite rotating vector in the αβ coordinate system.

[0006] Optionally, the step of constructing the positive and negative order operation matrix based on the fundamental wave synthesis rotation vector in the αβ coordinate system includes: Based on the fundamental wave synthesis rotation vector in the αβ coordinate system, an arbitrary delay component in the αβ coordinate system is constructed. Based on the fundamental wave synthesis rotation vector and the arbitrary delay component, a positive and negative order operation matrix is ​​constructed.

[0007] Optionally, the step of constructing arbitrary delay components in the αβ coordinate system based on the fundamental wave synthesis rotation vector in the αβ coordinate system includes: A synchronous delay operation is applied to the fundamental wave synthesis rotation vector in the αβ coordinate system to construct an arbitrary delay component in the αβ coordinate system.

[0008] Optionally, the step of constructing a positive / negative order operation matrix based on the fundamental synthesized rotation vector and the arbitrary delay component includes: Based on the fundamental wave synthesis rotation vector and the arbitrary delay component, a coefficient matrix is ​​constructed; The coefficient matrix is ​​inverted to construct a positive and negative order operation matrix.

[0009] Optionally, extracting the positive and negative order components based on the positive and negative order operation matrix includes: The matrix coefficients of the positive and negative order operation matrix are simplified by using trigonometric identity transformations to obtain a unified extraction matrix of positive and negative order components applicable to any delay duration. Using the equal division fixed-point rounding quantization formula, all matrix coefficients in the uniform extraction matrix of the positive and negative order components are discretized and approximated to determine the quantization processing matrix. Based on the quantization matrix, positive and negative order components are extracted.

[0010] Optionally, the step of extracting positive and negative order components based on the quantization processing matrix includes: The fundamental wave synthesis rotation vector and the arbitrary delay component are substituted into the quantization processing matrix to complete linear matrix operations, and positive and negative order components are output.

[0011] This application has the following beneficial effects: The method proposed in this application breaks through the constraints of fixed delay on the extraction time by flexibly configuring delay parameters, effectively improving the adaptability and extraction flexibility of the delay method under different working conditions, while retaining the inherent advantages of delay-type methods such as simple principle and small amount of computation. Attached Figure Description

[0012] Figure 1 A block diagram of a system for separating the fundamental positive and negative sequence components of electrical physical quantities based on arbitrary delay, provided in an embodiment of this application; Figure 2 A flowchart illustrating a method for rapidly extracting the positive and negative sequence components of a fundamental electrical physical quantity, provided in an embodiment of this application; Figure 3 A comparison diagram of the positive and negative sequence separation results and the actual component waveforms provided in the embodiments of this application. Detailed Implementation

[0013] To facilitate understanding by those skilled in the art, the present application will be further described below in conjunction with embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present application.

[0014] This application focuses on the rapid extraction of the positive and negative sequence components of fundamental electrical physical quantities. The process is as follows: Figure 1 As shown. The three-phase unbalanced voltage processing link is divided into an orthogonal transformation unit, a synchronization delay unit, a sequence component decoupling matrix, and... dq The system consists of five parts: a coordinate transformation unit and a phase-locked loop unit. The orthogonal transformation unit decouples the three-phase raw signals into two-phase stationary orthogonal components. The synchronization delay unit provides a customizable dual-channel equal-phase delay output. A unified extraction matrix for positive and negative sequence components is also included. M Based on the original and delayed sets of orthogonal components, the positive and negative αβ components are simultaneously separated, among which K 1. K 2 represents the operational coefficients after equal division and fixed-point rounding quantization, s represents the Laplace operator, T represents the time constant corresponding to the first-order inertial element, and PI represents the proportional-integral controller. dq The coordinate transformation unit realizes the sequential rotation coordinate system transformation, and the phase-locked loop unit outputs a synchronous phase to support Clark transformation. The entire topology relies on adjustable delay and algebraic matrix operations to achieve fast sequential component extraction without filtering.

[0015] To solve the above technical problems, such as Figure 2 As shown, this application proposes a method for fast extraction of the positive and negative sequence components of fundamental electrical physical quantities, including: Step S101: Real-time acquisition of three-phase fundamental voltage; The overall simulation system of this application exhibits asymmetrical component operation. The fundamental voltage component, containing negative sequence components, is extracted, and the expression for the three-phase voltage is as follows: (1) in, This is the three-phase fundamental voltage. These represent the amplitudes of the fundamental positive-sequence and negative-sequence components. The fundamental synchronous angular frequency, The initial phase angles of the positive and negative sequence components are denoted by , and t is time. The three-phase unbalanced electrical quantities can be decomposed into a superposition of the fundamental positive-sequence component and the negative-sequence component. By acquiring the three-phase fundamental voltage in real time, the positive and negative sequence electrical quantities under unbalanced conditions are fully preserved, providing data for subsequent accurate separation of positive and negative sequences.

[0016] Step S102: Based on the three-phase fundamental voltage, determine the fundamental wave synthesis rotation vector in the αβ coordinate system; The Clark transformation is applied to the aforementioned three-phase fundamental voltages, transforming them from a three-phase stationary coordinate system to a two-phase stationary coordinate system (αβ coordinate system), resulting in the fundamental composite rotating vector in the αβ coordinate system. This transformation reduces the computational dimensionality, simplifies the signal representation, and facilitates the separation and solution of positive and negative sequence components. The rotating vector containing the negative sequence component is shown in the following equation: (2) in, The fundamental wave synthesis rotation vector is derived from the fundamental wave positive sequence rotation vector. and fundamental negative sequence rotation vector synthesis.

[0017] The formula for coordinate transformation is: (3) Step S103: Based on the fundamental wave synthesis rotation vector in the αβ coordinate system, construct the positive and negative order operation matrix; By applying a synchronization delay operation to the fundamental wave synthesis rotation vector in the αβ coordinate system described above, an arbitrary delay component in the αβ coordinate system is constructed, as shown in the following equation: (4) In the formula, T delay To customize the synchronization delay duration, The delayed α and β components are derived from the delayed fundamental positive sequence components. and delayed fundamental negative sequence component synthesis.

[0018] By setting the delay parameters appropriately, high extraction accuracy can be maintained even with small fluctuations in the power grid frequency, which is superior to the frequency sensitivity of the fixed delay method.

[0019] Expanding the trigonometric functions in formula (4) and rearranging, we obtain the linear relationship between the delayed orthogonal components and the original αβ components: (5) By combining the fundamental wave rotational composite vector (Equation (2)) and the arbitrary delay component (Equation (5)), a system of four linear equations is constructed, namely the coefficient matrix T: (6) Inverting the coefficient matrix T to decouple the positive and negative ordered components allows us to calculate the matrix determinant. To ensure T The invertibility of a matrix must satisfy the following condition: Right now After performing operations according to the rules for solving inverse matrices, the expression for solving the ordinal components is obtained, i.e., the positive and negative order operation matrix H: (7) Step S104: Extract the positive and negative order components based on the positive and negative order operation matrix.

[0020] By simplifying the matrix coefficients of the positive and negative order operation matrix H using trigonometric identities, a unified extraction matrix for positive and negative order components applicable to arbitrary delay durations is obtained. M That is, the universal extraction formula for the positive and negative sequence components of the fundamental wave under arbitrary delay: (8) Because the positive and negative order components are extracted into a unified matrix M The cotangent and cosecant terms in the matrix are prone to irrational numbers. Therefore, a discrete approximation of all matrix coefficients is performed using the equal-division fixed-point rounding quantization formula: (9) In the formula, K real For matrix M Theoretical value N est To quantize resolution, K est This represents the quantized, actual usable value. Matrix coefficient quantization reduces floating-point operations, lowers computing power requirements, and facilitates real-time operation on the platform.

[0021] After the above processing, the quantization processing matrix M′ is obtained. The fundamental wave synthesis rotation vector in the αβ coordinate system and the arbitrary delay component in the αβ coordinate system are substituted into the quantization processing matrix M′ to complete linear matrix operations. Through algebraic decoupling, the cross-coupling terms of the positive and negative sequence rotation vectors are canceled, realizing the separation of the fundamental wave positive sequence component and negative sequence component in the αβ coordinate system, and outputting the positive and negative sequence components. and After dq coordinate transformation, the positive and negative order components in the dq coordinate system are obtained. and .

[0022] Simulation verification A simulation model was built using the MATLAB simulation platform. The fundamental positive sequence amplitude was set. The negative sequence component amplitude is 1000 V. 500 V, fundamental synchronous angular frequency The initial phase angles of both positive and negative sequence components are 0, and the synchronization delay duration is... T delay Set to 2.5ms, quantization resolution N est The value is 10000.

[0023] Based on the simulation verification of the rapid extraction of the positive and negative sequence components of the fundamental electrical physical quantities, the results are as follows: Figure 3 As shown in the figure. Simulation results show that the waveform of the sequence component obtained by the algorithm of this invention highly coincides with the theoretical true value, fully verifying the correctness and effectiveness of the positive and negative sequence extraction scheme. This algorithm can complete the decoupling of positive and negative sequence components under arbitrary delay conditions, has strong adaptability to operating conditions, and has important application value in engineering scenarios such as real-time control of power electronic converters with variable interface delays and flexible DC transmission.

[0024] In summary, the method proposed in this application, by flexibly configuring delay parameters, breaks through the constraints of fixed delay on the extraction time, effectively improving the adaptability and extraction flexibility of the delay method under different working conditions, while retaining the inherent advantages of delay-type methods such as simple principle and low computational load.

[0025] In some embodiments, this application also provides a computer system including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0026] This application also provides a computer-readable storage medium for storing a computer program. This computer-readable storage medium can be applied to a computer device, and the computer program causes the computer device to execute the corresponding processes in the methods described above in the embodiments of this application; for brevity, further details are omitted here.

[0027] The above embodiments are preferred implementations of this application. In addition, this application can be implemented in other ways. Any obvious substitutions without departing from the concept of this technical solution are within the protection scope of this application.

[0028] To facilitate understanding by those skilled in the art of the improvements made by this application compared to the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this application.

Claims

1. A method for rapidly extracting the positive and negative sequence components of a fundamental electrical physical quantity, characterized in that, include: Real-time acquisition of three-phase fundamental voltage; Based on the three-phase fundamental voltage, determine the fundamental wave synthesis rotation vector in the αβ coordinate system; Based on the fundamental wave synthesis rotation vector in the αβ coordinate system, construct the positive and negative order operation matrix; Based on the positive and negative order operation matrix, the positive and negative order components are extracted.

2. The method according to claim 1, characterized in that, The determination of the fundamental wave synthesis rotation vector in the αβ coordinate system based on the three-phase fundamental wave voltage includes: The three-phase fundamental voltages are subjected to Clark transformation to obtain the fundamental composite rotating vector in the αβ coordinate system.

3. The method according to claim 2, characterized in that, The construction of the positive and negative order operation matrix based on the fundamental wave synthesis rotation vector in the αβ coordinate system includes: Based on the fundamental wave synthesis rotation vector in the αβ coordinate system, an arbitrary delay component in the αβ coordinate system is constructed. Based on the fundamental wave synthesis rotation vector and the arbitrary delay component, a positive and negative order operation matrix is ​​constructed.

4. The method according to claim 3, characterized in that, The construction of arbitrary delay components in the αβ coordinate system based on the fundamental wave synthesis rotation vector in the αβ coordinate system includes: A synchronous delay operation is applied to the fundamental wave synthesis rotation vector in the αβ coordinate system to construct an arbitrary delay component in the αβ coordinate system.

5. The method according to claim 3, characterized in that, The construction of a positive and negative order operation matrix based on the fundamental synthesized rotation vector and the arbitrary delay component includes: Based on the fundamental wave synthesis rotation vector and the arbitrary delay component, a coefficient matrix is ​​constructed; The coefficient matrix is ​​inverted to construct a positive and negative order operation matrix.

6. The method according to claim 5, characterized in that, The step of extracting positive and negative components based on the positive and negative order operation matrix includes: The matrix coefficients of the positive and negative order operation matrix are simplified by using trigonometric identity transformations to obtain a unified extraction matrix of positive and negative order components applicable to any delay duration. The equal division fixed-point rounding quantization formula is used to make discrete approximations of all matrix coefficients in the uniform extraction matrix of the positive and negative order components to determine the quantization processing matrix. Based on the quantization matrix, positive and negative order components are extracted.

7. The method according to claim 6, characterized in that, The step of extracting positive and negative order components based on the quantization processing matrix includes: The fundamental wave synthesis rotation vector and the arbitrary delay component are substituted into the quantization processing matrix to complete linear matrix operations, and positive and negative order components are output.

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