CN-121984137-A - Double-layer frequency modulation and voltage regulation control method with participation of virtual synchronous machine

CN121984137ACN 121984137 ACN121984137 ACN 121984137ACN-121984137-A

Abstract

The invention discloses a double-layer frequency modulation and voltage regulation control method participated by a virtual synchronous machine, which comprises a rapid inertia response process and an active frequency modulation recovery process, wherein the rapid inertia response process comprises the steps that when the frequency deviation change rate exceeds a preset threshold value, VSG generates additional active power inversely proportional to the frequency deviation change rate and adds the active power to act on the VSG, and the active frequency modulation recovery process comprises the steps that when the frequency deviation continuously exists for a time exceeding the preset value, the VSG calculates the active power correction, and the active power correction is generated through a PI controller of the VSG or the active power correction is generated through a water turbine governor and acts on the total active power until the frequency is recovered to a rated value. The invention adopts the whole process frequency control method, provides a 'passive+active' double-layer frequency modulation architecture, not only suppresses frequency shock, but also eliminates steady-state deviation, and realizes the 'dynamic suppression-steady-state recovery' closed-loop control process of the frequency.

Inventors

CHEN TING
NI YUFEI
LIN TINGTING
MENG KE
JIN HUAPIN
Dong dafu
LIN NING
WU TAO
FANG MENG
ZHANG TIAN
SU YIJUAN

Assignees

水利部农村电气化研究所
水利部交通运输部国家能源局南京水利科学研究院

Dates

Publication Date: 20260505
Application Date: 20251216

Claims (10)

1. A double-layer frequency modulation and voltage regulation control method participated by a virtual synchronous machine is characterized by comprising the following steps: A fast inertial response process and an active fm recovery process, The fast inertial response process comprises the following steps: When the frequency deviation change rate exceeds a preset threshold value, the VSG generates additional active power inversely proportional to the frequency deviation change rate, and the additional active power acts on the VSG; the active frequency modulation recovery process comprises the following steps: When the duration of the frequency deviation exceeds a preset value, the VSG calculates an active power correction amount, and the active power correction amount is generated through a PI controller of the VSG or the active power correction amount is generated through a water turbine speed regulator to act on the total active power until the frequency is restored to a rated value.
2. The method for controlling the double-layer frequency modulation and voltage regulation with the participation of the virtual synchronous machine according to claim 1, wherein the calculation formula of the additional active power is as follows: ; In the formula, Is a virtual moment of inertia; Is the angular frequency of the system.
3. The method for controlling double-layer frequency modulation and voltage regulation with participation of a virtual synchronous machine according to claim 1 or 2, wherein the response time range of the fast inertial response process is 50 ms-200 ms.
4. The method for controlling the double-layer frequency modulation and voltage regulation with participation of the virtual synchronous machine according to claim 1, wherein the calculation formula of the active power correction amount is as follows: ; In the formula, 、 Proportional and integral gains, respectively; Is the frequency offset.
5. The method for controlling double-layer frequency and voltage modulation with participation of a virtual synchronous machine according to claim 4, wherein the range of the proportional gain is 0.05-0.2.
6. The method for controlling the dual-layer frequency and voltage modulation with participation of the virtual synchronous machine according to claim 1, wherein the method for controlling the dual-layer frequency and voltage modulation with participation of the virtual synchronous machine further comprises the following steps: An instantaneous reactive support process and a voltage steady state recovery process, Wherein the instantaneous reactive power support process comprises: when the voltage is suddenly changed, outputting capacitive reactive power based on the VSG virtual reactance; The voltage steady state recovery process includes: when the voltage has deviation, the PI controller of the VSG generates a voltage correction amount to realize the stable state recovery of the voltage.
7. The method for controlling the double-layer frequency and voltage modulation participated by the virtual synchronous machine according to claim 6, wherein the output capacitive reactive power is: ; Wherein V 0 is rated voltage, V is measured voltage, and X v is VSG virtual reactance.
8. The method for controlling the double-layer frequency and voltage regulation of the participation of the virtual synchronous machine according to claim 1, wherein the method for controlling the double-layer frequency and voltage regulation of the participation of the virtual synchronous machine further comprises the steps of identifying a power grid mode, executing only a fast inertia response process when the power grid mode is a grid-connected mode, and executing the fast inertia response process and an active frequency modulation recovery process simultaneously when the power grid mode is an island mode.
9. The method for controlling the double-layer frequency and voltage modulation with participation of the virtual synchronous machine according to claim 1, wherein in the active frequency modulation recovery process, when a plurality of VSGs exist and active power correction amounts are generated through PI regulators of the VSGs, the calculated active power correction amounts are distributed to the VSGs according to a preset distribution mode, and the corresponding active power correction amounts are generated by the PI regulators of the VSGs.
10. The method for controlling the dual-layer frequency and voltage modulation with participation of the virtual synchronous machine according to claim 9, wherein the formula of the preset allocation mode is as follows: ; Wherein k i is the power distribution coefficient of the ith VSG unit, P rated,i is the rated active power of the ith VSG unit; The sum of the rated powers of all VSG units participating in group control.

Description

Double-layer frequency modulation and voltage regulation control method with participation of virtual synchronous machine Technical Field The invention relates to the technical field of frequency and voltage regulation of an electric power system, in particular to a double-layer frequency regulation control method applied to participation of a virtual synchronous machine of a small water electric micro-grid or a distributed power system. Background Along with the continuous improvement of the permeability of distributed power sources such as small hydropower stations, photovoltaics, wind power and the like in a power distribution network, the number of traditional synchronous machines is reduced, the overall inertia level of the system is reduced, and the frequency adjusting capability is weakened. Under the disturbance of sudden load increase or power off-grid, the system frequency is easy to have the problems of rapid sliding down, too low lowest point, long recovery time and the like, and the safe operation of the power grid is seriously threatened. Virtual Synchronous Generator (VSG) technology provides instantaneous power support at the beginning of a disturbance by simulating the rotor motion equation of the synchronous generator in a power electronic converter controller, imparting virtual inertia and damping characteristics to the synchronous generator, and effectively suppressing the rate of change of frequency (RoCoF), referred to as "passive inertial response". However, the existing VSG control mostly only implements the primary frequency modulation function, and has the following limitations: the steady-state frequency deviation cannot be eliminated, namely the traditional VSG depends on droop control or fixed power output, the frequency cannot be recovered to the rated value after disturbance, and static errors exist; The VSG controller usually operates independently, is not cooperated with a water turbine speed regulator or an upper energy management system, and is difficult to realize secondary frequency modulation; the control level is single, most schemes design inertia response and power adjustment coupling, and the response speed and the steady-state precision are difficult to consider; the voltage regulating capability is insufficient, namely the prior research on multi-focus frequency control has less attention on a cooperative mechanism of VSG participating in reactive power/voltage regulation; The recovery process is slow, namely, in a small hydropower system, the mechanical speed regulator responds slowly (in the order of seconds), so that the frequency recovery time is too long, and the power supply quality is affected. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a double-layer frequency and voltage modulation control method participated by a virtual synchronous machine, which aims at solving the technical problems that in the prior art, only a primary frequency modulation function is realized and active regulation capability is lacking. The invention provides a double-layer frequency and voltage modulation control method participated by a virtual synchronous machine, which comprises the following steps: A fast inertial response process and an active fm recovery process, The fast inertial response process comprises the following steps: When the frequency deviation change rate exceeds a preset threshold value, the VSG generates additional active power inversely proportional to the frequency deviation change rate, and the additional active power acts on the VSG; the active frequency modulation recovery process comprises the following steps: When the duration of the frequency deviation exceeds a preset value, the VSG calculates an active power correction amount, and the active power correction amount is generated through a PI controller of the VSG or the active power correction amount is generated through a water turbine speed regulator to act on the total active power until the frequency is restored to a rated value. Further, the calculation formula of the additional active power is as follows: ; In the formula, Is a virtual moment of inertia; Is the angular frequency of the system. Further, the response time range of the rapid inertial response process is 50 ms-200 ms. Further, the calculation formula of the active power correction amount is as follows: ; In the formula, 、Proportional and integral gains, respectively; Is the frequency offset. Further, the range of the proportional gain is 0.05-0.2. Further, the double-layer frequency modulation and voltage regulation control method participated by the virtual synchronous machine further comprises the following steps: An instantaneous reactive support process and a voltage steady state recovery process, Wherein the instantaneous reactive power support process comprises: when the voltage is suddenly changed, outputting capacitive reactive power based on the VSG virtual reactance; The voltage s