Virtual synchronous machine series compensation grid-connected system subsynchronous oscillation suppression method and control system

Abstract

The invention discloses a virtual synchronous machine series compensation grid-connected system subsynchronous oscillation suppression method and control system. The method comprises the steps: collecting the current {ia, ib, ic} of a grid-connected inverter filter inductor L1, and multiplying the current {ia, ib, ic} by an impedance remodeling control coefficient H1 (s) to obtain a modulation signal feedback value {[detla]sa, [detla]sb, [detla]sc}; subtracting the modulation signal feedback value {[detla]sa, [detla]sa, [detla]sc} from a virtual synchronous machine modulation signal {sa, sb, sc} to obtain a grid-connected inverter modulation signal {sa-[detla]sa, sb-[detla]sb, sc-[detla]sc} with increased impedance remodeling control; and controlling the grid-connected inverter to operatethrough PWM modulation. According to the method, the low-frequency-band impedance of the virtual synchronous machine is reshaped into the characteristics of strong resistance and weak inductance, so that subsynchronous oscillation caused by impedance coupling of the virtual synchronous machine and the series compensation line can be well suppressed, additional impedance equipment does not need tobe added, and the cost is low.

Description

technical field [0001] The invention relates to the field of new energy power generation control, in particular to a subsynchronous oscillation suppression method and control system of a virtual synchronous machine series compensation grid-connected system. Background technique [0002] In recent years, new energy power generation represented by photovoltaics and wind turbines has developed rapidly. New energy power stations are usually far away from the power load center, and electric energy needs to be transmitted over long distances. In order to improve transmission efficiency, series capacitors are usually used to reduce reactive power consumption during transmission. The large-scale connection of new energy generation based on power electronic devices to the power grid will cause a series of stability problems. The subsynchronous oscillation problem of large-scale wind farms connected to the grid through series-compensated transmission lines has received extensive atten...

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Problems solved by technology

At present, only some demonstration projects have been built for new energy power generation based on virtual synchronous machine control. Grid-connected inverters based on virtual synchronous machine control have not yet been applied to modern power systems on a large scale. Therefore, the series compensation grid-connected system based on virtual synchronous machine The subsynchronous oscillation problem has not attracted the attention of industry and academia

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