CN-114498676-B - Synchronous oscillation suppression method and device for power synchronous control converter

CN114498676BCN 114498676 BCN114498676 BCN 114498676BCN-114498676-B

Abstract

The invention relates to a synchronous oscillation suppression method and a synchronous oscillation suppression device for a power synchronous control converter, which are used for obtaining a first difference delta P between an active power reference value and an active power measured value of a grid-connected point of the power synchronous control converter; the method comprises the steps of obtaining a first difference value delta Q of a reactive power reference value and a reactive power measurement value of a grid-connected point of a power synchronous control converter, limiting a synchronous frequency component of the first difference value delta P through a first band-stop filter to obtain a second difference value delta P, obtaining a reference phase of a modulation signal according to the second difference value delta P, limiting the synchronous frequency component of the first difference value delta Q through a second band-stop filter to obtain a second difference value delta Q, calculating to obtain a reference voltage amplitude of the modulation signal according to the second difference value delta Q, and generating the modulation signal of the control power synchronous control converter according to the reference phase and the reference voltage amplitude of the modulation signal. The invention can effectively restrain the synchronous oscillation in the operation of the power synchronous control converter.

Inventors

XIONG XIAOLING
ZHOU YAN
YANG YUCHEN
Luo Bochen

Assignees

华北电力大学

Dates

Publication Date: 20260505
Application Date: 20220125

Claims (6)

1. A synchronous oscillation suppression method for a power synchronous control converter, comprising the steps of: Step1, acquiring a first difference delta P1 between an active power reference value P ref and an active power measured value P out of a grid-connected point of a power synchronous control converter; acquiring a first difference delta Q1 between a reactive power reference value Q ref and a reactive power measured value Q out of a grid-connected point of the power synchronous control converter; Step 2, limiting synchronous frequency components of the first difference delta P1 through a first band-stop filter to obtain a second difference delta P2, and calculating through an active power control loop according to the second difference delta P2 to obtain a reference phase delta ref of a modulation signal; Limiting the synchronous frequency component of the first difference DeltaQ 1 through a second band-stop filter to obtain a second difference DeltaQ 2, and calculating through a reactive power control loop according to the second difference DeltaQ 2 to obtain a reference voltage amplitude V ref of a modulation signal; Step 3, generating a modulation signal for controlling the power synchronous control converter according to the reference phase delta ref and the reference voltage amplitude V ref of the modulation signal, transmitting the modulation signal to a PWM generator, and generating a PWM signal for controlling the power synchronous control converter; In step 2, the reference phase delta ref of the modulation signal obtained by the active power control loop calculation is realized by the following method, Obtaining a frequency deviation according to the second difference value delta P2 and the active droop coefficient D p , adding the frequency deviation and the synchronous angular frequency omega 0 of the power grid, and obtaining a reference phase delta through integral transformation ref; In step 2, the reactive power control loop calculates the reference voltage amplitude V ref of the obtained modulation signal by the following method, Obtaining a frequency deviation according to the second difference value delta Q2 and the reactive droop coefficient D q , adding the frequency deviation and the synchronous angular frequency omega 0 of the power grid, and obtaining a reference voltage amplitude V ref through integral transformation.
2. The method of claim 1, wherein in step2, the transfer functions of the first band reject filter and the second band reject filter are, Where s is Laplacian, ω 0 is the synchronous angular frequency of the grid, and ζ is the damping coefficient.
3. A synchronous oscillation suppression method as defined in claim 2, wherein the damping coefficient ζ is determined, According to the frequency spectrum characteristics of the power synchronous oscillation, an upper limit frequency f 2 and a lower limit frequency f 1 which are symmetrical with respect to the synchronous frequency f 0 are selected, so that the bandwidth delta omega=2pi (f 2 -f 1 ) and the damping coefficient xi= delta omega/omega 0 are obtained.
4. The method of claim 1, wherein in step 1, the active power measurement value P out and the reactive power measurement value Q out are obtained by direct measurement at a grid connection point of the power synchronous control converter.
5. A synchronous oscillation suppression device for a power synchronous control inverter, comprising: The active power control module comprises a first band-stop filter, wherein the first band-stop filter is used for limiting synchronous frequency components of a first difference value delta P1, a second difference value delta P2 is obtained, a reference phase delta ref of a modulation signal is obtained through calculation of an active power control loop according to the second difference value delta P2, and the first difference value delta P1 is a difference value between an active power reference value P ref and an active power measurement value P out of a parallel point of the power synchronous control converter; The reactive power control module comprises a second band-stop filter, wherein the second band-stop filter is used for limiting synchronous frequency components of a first difference value delta Q1 to obtain a second difference value delta Q2, and the reference voltage amplitude V ref of a modulation signal is obtained through calculation of a reactive power control loop according to the second difference value delta Q2, wherein the first difference value delta Q1 is the difference value between a reactive power reference value Q ref and a reactive power measurement value Q out of a grid-connected point of the power synchronous control converter; The modulation signal generation module generates a modulation signal for controlling the power synchronous control converter according to the reference phase delta ref and the reference voltage amplitude V ref ; A PWM generator that generates the modulation signal into a PWM signal that controls a power synchronous control inverter; the reference phase delta ref of the modulation signal obtained by the active power control loop calculation is realized by the following method, Obtaining a frequency deviation according to the second difference value delta P2 and the active droop coefficient D p , adding the frequency deviation and the synchronous angular frequency omega 0 of the power grid, and obtaining a reference phase delta ref through integral transformation; The reference voltage amplitude V ref of the modulation signal obtained by the reactive power control loop calculation is realized by the following method, Obtaining a frequency deviation according to the second difference value delta Q2 and the reactive droop coefficient D q , adding the frequency deviation and the synchronous angular frequency omega 0 of the power grid, and obtaining a reference voltage amplitude V ref through integral transformation.
6. The synchronous oscillation suppression device according to claim 5, wherein the transfer functions of the first band reject filter and the second band reject filter are, Where s is Laplacian, ω 0 is the synchronous angular frequency of the grid, and ζ is the damping coefficient.

Description

Synchronous oscillation suppression method and device for power synchronous control converter Technical Field The invention relates to a synchronous oscillation suppression method and device for a power synchronous control converter. Background The common voltage source type converters (voltage source converters, VSC) are divided into two types, namely a grid following type converter (grid-followingconverter) and a power synchronous control converter (grid-forming converter) according to different synchronous modes. Compared with the early power grid following type converter, the power synchronous control converter can provide voltage and frequency support, along with the increasing of the grid connection proportion of new energy, the traditional synchronous generator in the power grid is gradually banned, the voltage and frequency standard of the power grid cannot be determined depending on the synchronous generator, and the power synchronous control converter becomes a research focus due to the capability of providing voltage and frequency support and has very wide application prospect. However, since the power control of the converter is performed by adopting droop control, the power control of the converter lacks damping characteristics, and synchronous oscillation is easy to occur in the operation process, so that the system is unstable, and the converter is a disadvantageous factor for safe and stable operation of a power grid. In addition, the coupling effect of the active loop and the reactive loop in the power control loop has an aggravating effect on the synchronous frequency oscillation phenomenon, is equivalent to introducing negative damping, and also reduces the stability of the system. Based on the background, the problem of restraining the synchronous oscillation of the power synchronous control converter is a problem to be solved urgently, and the method has important significance for guaranteeing that the power grid with continuously increased new energy grid-connected proportion maintains stable operation. Disclosure of Invention The invention aims to provide a synchronous oscillation suppression method and device for a power synchronous control converter, which can effectively suppress synchronous oscillation in the operation of the power synchronous control converter. Based on the same inventive concept, the invention has two independent technical schemes: 1. a synchronous oscillation suppression method for a power synchronous control inverter, comprising the steps of: Step1, acquiring a first difference delta P1 between an active power reference value P ref and an active power measured value P out of a grid-connected point of a power synchronous control converter; acquiring a first difference delta Q1 between a reactive power reference value Q ref and a reactive power measured value Q out of a grid-connected point of the power synchronous control converter; Step 2, limiting synchronous frequency components of the first difference delta P1 through a first band-stop filter to obtain a second difference delta P2, and calculating through an active power control loop according to the second difference delta P2 to obtain a reference phase delta ref of a modulation signal; Limiting the synchronous frequency component of the first difference DeltaQ 1 through a second band-stop filter to obtain a second difference DeltaQ 2, and calculating through a reactive power control loop according to the second difference DeltaQ 2 to obtain a reference voltage amplitude V ref of a modulation signal; And 3, generating a modulation signal for controlling the power synchronous control converter according to the reference phase delta ref and the reference voltage amplitude V ref of the modulation signal, and transmitting the modulation signal to a PWM generator to generate a PWM signal for controlling the power synchronous control converter. Further, in step 2, the transfer functions of the first band-stop filter and the second band-stop filter are, Where s is Laplacian, ω 0 is the synchronous angular frequency of the grid, and ζ is the damping coefficient. Further, the damping coefficient xi is determined by, According to the frequency spectrum characteristics of the power synchronous oscillation, an upper limit frequency f 2 and a lower limit frequency f 1 which are symmetrical with respect to the synchronous frequency f 0 are selected, so that the bandwidth delta omega=2pi (f 2-f1) and the damping coefficient xi= delta omega/omega 0 are obtained. Further, in step 1, the active power measurement value P out and the reactive power measurement value Q out are obtained by direct measurement at the grid-connected point of the power synchronous control converter. Further, in step 2, the reference phase O ref of the modulation signal obtained by active power control loop calculation is implemented by the following method, Obtaining a frequency deviation according to the second difference value DeltaP 2 and the ac