Start-stop method for unified power flow controller

Abstract

The invention discloses a start-stop method for a unified power flow controller. A start process comprises the steps of placing a parallel-side transformer into a parallel-side converter for charging and then unlocking the parallel-side converter to control the direct current voltage to be stable; unlocking a serial-side converter, and controlling the current of a by-pass switch of the serial-side converter to be close to zero; disconnecting the by-pass switch to connect a serial-side transformer to a line in series, wherein the serial-side converter enters a normal operation mode when the line stably runs; and during stop, switching the control mode of the serial-side converter firstly to enable the by-pass switch to be switched on in vicinity of zero current, controlling the current of the serial-side transformer to be gradually reduced into zero and stop the serial-side transformer, and then locking the serial-side converter and the parallel-side converter and stopping the parallel-side transformer. By the start-stop method for the unified power flow controller, the direct current overvoltage and overcurrent of the converter can be effectively inhibited when the serial-side transformer is switched off, the compact of current oscillation of an alternating current line to the serial-side transformer is reduced, and stable start and stop of the unified power flow controller are realized.

Description

technical field [0001] The invention relates to a flexible AC power transmission technology, in particular to a starting and stopping method of a unified power flow controller. Background technique [0002] With the interconnection of large-scale power systems and the use of various new equipment, the scale and complexity of the power system have also increased while making power generation and transmission more economical and efficient; coupled with a large number of distributed power generation systems connected to the grid , so that the traditional fixed power flow transmitted from the transmission network to the distribution network is reversed; the continuous growth of user load requires power flow control means to improve the existing power transmission capacity; the complex power exchange between the booming smart grid and the power market requires Frequent flow control. [0003] The unified power flow controller, also known as UPFC (UnifiedPowerFlowController), is t...

AI Technical Summary

Problems solved by technology

The way of shutting down is opposite to the starting procedure, respectively lock the converters on both sides and then exit the transformer. In this way of starting and stopping, when the transformer on the series side is switched on but the converter is not unlocked or the converter is blocked, the transformer and the series The side converter generates a large voltage, which even saturates the transformer, and at the same time causes overcharge of the converter capacitor, which affects the safety of the converter equipment; in addition, the line current will also have a large voltage when the transformer is put in and out. sudden change, which has a great influence on the power flow of the AC system

Images