CN-121984004-A - Subsynchronous harmonic compensation method and device for electric power system

CN121984004ACN 121984004 ACN121984004 ACN 121984004ACN-121984004-A

Abstract

The invention discloses a subsynchronous harmonic compensation method and device for a power system. The method comprises the steps of obtaining a real-time load current signal, carrying out windowing processing on the real-time load current signal based on a preset first window function to obtain a first windowed current signal, carrying out peak detection on the first windowed current signal in a preset frequency range to obtain respective frequencies, amplitudes and phases of a plurality of subsynchronous harmonics, judging whether to keep the first window function or not based on the frequencies, the amplitudes and the phases of the subsynchronous harmonics, generating sine wave signals corresponding to the subsynchronous harmonics based on the respective frequencies, the amplitudes and the phases of the subsynchronous harmonics, and compensating the real-time load current signal through a unified power quality regulator based on the sine wave signals corresponding to the subsynchronous harmonics. The invention solves the technical problems of low detection precision and weak separation capability of the subsynchronous harmonic wave of the conventional unified power quality regulator.

Inventors

LI ZHUOQUN
WAN YI
LIU XIULAN
CHEN XI
JIN YUAN
GU JUN
DAI HANQI
YUAN XIAOXI
LIU XIANGLU
CHEN HUIMIN

Assignees

国网北京市电力公司

Dates

Publication Date: 20260505
Application Date: 20260320

Claims (10)

1. A method of subsynchronous harmonic compensation of an electrical power system, comprising: Acquiring a real-time load current signal of a load side of the unified power quality regulator in a preset time period; windowing the real-time load current signal based on a preset first window function to obtain a first windowed current signal; In a preset frequency range, carrying out peak detection on the first windowed current signal to obtain the frequency, amplitude and phase of each of a plurality of subsynchronous harmonics; judging whether to maintain the first window function or not based on the frequency and the amplitude of the plurality of subsynchronous harmonics; generating sine wave signals corresponding to the plurality of sub-synchronous harmonics based on the frequency, the amplitude and the phase of the plurality of sub-synchronous harmonics respectively under the condition that the judgment result is that the first window function is kept; and compensating the real-time load current signal through the unified power quality conditioner based on the sine wave signals corresponding to the sub-synchronous harmonics.
2. The method of claim 1, wherein the acquiring a real-time load current signal on the load side of the unified power quality conditioner for a preset period of time comprises: collecting three-phase load current signals at the load side; Converting the three-phase load current signal into a two-phase load current signal through coordinate transformation; sampling the two-phase load current signal based on a preset sampling rate to obtain a sampled load current signal; calculating a direct current component in the sampling load current signal based on a preset cache point number; And removing the direct current component from the sampled load current signal to obtain the real-time load current signal.
3. The method of claim 1, wherein peak detecting the first windowed current signal over a predetermined frequency range to obtain the frequency, amplitude, and phase of each of a plurality of sub-synchronous harmonics comprises: determining all maximum amplitudes within the preset frequency range; Calculating a noise filtering threshold based on all the maximum magnitudes; Removing the maximum amplitude values lower than the noise filtering threshold value in all the maximum amplitude values to obtain a plurality of target maximum amplitude values, and determining the frequency corresponding to each of the plurality of target maximum amplitude values; correcting the multiple target maximum amplitude values and the frequencies corresponding to the multiple target maximum amplitude values respectively through a three-point difference method to obtain the frequencies and the amplitudes of the multiple sub-synchronous harmonics corresponding to the multiple target maximum amplitude values respectively; The respective phases of the plurality of sub-synchronous harmonics are determined based on the respective frequencies, amplitudes of the plurality of sub-synchronous harmonics.
4. The method of claim 1, wherein the determining whether to maintain the first window function based on the frequency, amplitude, and/or the like of the plurality of subsynchronous harmonics comprises: determining the subsynchronous harmonic with the largest amplitude value among the subsynchronous harmonics as a target subsynchronous harmonic; determining a spectrum leakage degree based on the amplitude of the target subsynchronous harmonic; comparing the spectrum leakage degree with a preset leakage threshold value; And determining to maintain the first window function under the condition that the frequency spectrum leakage degree is smaller than the preset leakage threshold value.
5. The method as recited in claim 1, further comprising: Under the condition that the judging result is that the first window function is switched, re-windowing processing is carried out on the real-time load current signal based on a preset second window function, so that a second windowed current signal is obtained; and continuing the peak detection operation on the second windowed current signal.
6. The method of claim 5, wherein the first window function is a hanning window function and the second window function is a blackman window function.
7. A subsynchronous harmonic compensation device of an electric power system, comprising: The acquisition module is used for acquiring real-time load current signals of the load side of the unified power quality regulator in a preset time period; The windowing module is used for windowing the real-time load current signal based on a preset first window function to obtain a first windowed current signal; the detection module is used for carrying out peak detection on the first windowed current signal in a preset frequency range to obtain the frequency, amplitude and phase of each of a plurality of subsynchronous harmonics; A judging module, configured to judge whether to maintain the first window function based on the frequencies and the amplitudes of the multiple subsynchronous harmonics; the generation module is used for generating sine wave signals corresponding to the sub-synchronous harmonics based on the frequency, the amplitude and the phase of the sub-synchronous harmonics respectively under the condition that the judgment result is that the first window function is kept; and the compensation module is used for compensating the real-time load current signal through the unified power quality regulator based on the sine wave signals corresponding to the sub-synchronous harmonics.
8. A non-volatile storage medium, characterized in that the non-volatile storage medium comprises a stored program, wherein the program, when run, controls a device in which the non-volatile storage medium is located to perform the subsynchronous harmonic compensation method of the power system according to any one of claims 1 to 6.
9. A computer device is characterized by comprising a memory and a processor, The memory stores a computer program; The processor for executing a computer program stored in the memory, which when run causes the processor to perform the subsynchronous harmonic compensation method of the power system of any of claims 1 to 6.
10. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements a subsynchronous harmonic compensation method of an electric power system according to any one of claims 1 to 6.

Description

Subsynchronous harmonic compensation method and device for electric power system Technical Field The invention relates to the technical field of harmonic compensation of power systems, in particular to a subsynchronous harmonic compensation method and device of a power system. Background With the rapid development of power electronics technology and the large-scale grid connection of new energy power generation systems, the nonlinear, impact and fluctuation load duty ratio in the power system is continuously increased, so that the problem of power quality is increasingly complex. Besides the traditional voltage fluctuation, three-phase unbalance and integral harmonic pollution, subsynchronous harmonic (low-frequency harmonic component with frequency lower than power frequency 50/60 Hz) is becoming a new generation of key hidden trouble threatening the safe and stable operation of the power grid due to the characteristics of wide spectrum distribution, large amplitude fluctuation, easy formation of resonance with system impedance and the like. Although the current mainstream unified power quality conditioner (Unified Power Quality Conditioner, UPQC) can effectively solve the problems of fundamental wave integer harmonic wave, voltage sag, reactive power and the like, the core harmonic wave detection and compensation mechanism still adopts the traditional method, and the subsynchronous harmonic wave identification and response capability is seriously insufficient. In the existing detection technology, the method based on the instantaneous reactive power theory is highly dependent on the sine premise of the power grid voltage, detection drift is caused by fundamental wave phase misalignment under the condition of subsynchronous disturbance, although the synchronous rotation coordinate system conversion method can map a power frequency fundamental wave into a direct current component, subsynchronous harmonic waves are overlapped with the direct current component as low-frequency alternating current components and cannot be effectively separated to cause compensation instruction aliasing, and the wavelet conversion isochronous frequency analysis method has local feature extraction capability, but has high calculation complexity and poor instantaneity, and is difficult to embed a high-speed closed-loop control architecture of UPQC. More importantly, the current main scheme does not generally optimize the algorithm aiming at the frequency domain characteristics (such as frequency drift, narrow-band distribution and low signal to noise ratio) of the subsynchronous harmonic, so that the frequency spectrum in the detection window is seriously leaked, the frequency resolution is insufficient, the peak misjudgment rate is high, further the compensation instruction is misaligned, even the compensation current is reversely injected, and the system disturbance is aggravated. In view of the above problems, no effective solution has been proposed at present. Disclosure of Invention The embodiment of the invention provides a subsynchronous harmonic compensation method and device of an electric power system, which at least solve the technical problems of low subsynchronous harmonic detection precision and weak separation capacity of the conventional unified power quality regulator. According to one aspect of the embodiment of the invention, a sub-synchronous harmonic compensation method of an electric power system is provided, and the method comprises the steps of obtaining real-time load current signals of a load side of a unified electric energy quality regulator in a preset time period, windowing the real-time load current signals based on a preset first window function to obtain first windowed current signals, carrying out peak detection on the first windowed current signals in a preset frequency range to obtain respective frequencies, amplitudes and phases of a plurality of sub-synchronous harmonics, judging whether the first window function is kept or not based on the frequencies and the amplitudes of the plurality of sub-synchronous harmonics, generating sine wave signals corresponding to the plurality of sub-synchronous harmonics based on the respective frequencies, the amplitudes and the phases of the plurality of sub-synchronous harmonics when the judging result is that the first window function is kept, and compensating the real-time load current signals through the unified electric energy quality regulator based on the sine wave signals corresponding to the plurality of the sub-synchronous harmonics. The method comprises the steps of acquiring a three-phase load current signal on a load side, converting the three-phase load current signal into a two-phase load current signal through coordinate transformation, sampling the two-phase load current signal based on a preset sampling rate to obtain a sampling load current signal, calculating a direct current component in the sampling load current signal based on a prese