Optimization control method suitable for UHVDC commutation failure fault recovery

Abstract

The invention discloses an optimization control method suitable for UHVDC commutation failure fault recovery. The method comprises the following steps: 1, acquiring a DC voltage, a DC current, a converter turn-off angle and a bus phase voltage of an AC system at an inverter side of a UHVDC system in real time; 2, constructing dynamic current margin control by using a difference value between a rectification side-direct current instruction value and an inversion side direct-current measurement value and a slope of a current margin function; and 3, after the fault is cleared, through the inverter side converter, adopting constant current control to make the dynamic current margin control take effect, so that the current margin in the fault recovery process is reduced. According to the method, the direct-current control target in the UHVDC system low current recovery process can be determined, so that the probability of unstable recovery of the system caused by improper interaction of the rectification side constant current controller and the inversion side constant current controller is reduced, and the subsequent commutation failure generated in the UHVDC fault recovery process is effectively inhibited.

Description

technical field [0001] The invention relates to an optimized control method suitable for UHVDC commutation failure fault recovery, and belongs to the technical field of commutation failure suppression of high-voltage direct current transmission systems. Background technique [0002] With the increasing demand for transmission capacity and transmission distance in the interconnection of the eastern and western power grids, the UHVDC system has obvious advantages in large-capacity, long-distance power transmission and power system networking, and has become an "AC-DC hybrid" An important part of the grid. UHVDC systems all use thyristors as commutation components, and need to rely on grid voltage to restore their own blocking capability. Therefore, the inverter side converter is vulnerable to commutation failure due to grid faults. [0003] Since the suppression of the first commutation failure requires extremely high prediction response speed of the controller, it is difficu...

AI Technical Summary

Problems solved by technology

Due to the improper interaction of constant current control on the rectifier side and the inverter side during the fault recovery process of the UHVDC system, the DC current control target is not clear, causing oscillation and overshoot, and the current deviation control output quickly drops to 0, and switches to After the turn-off angle control is fixed, the current deviation control cannot correctly increase the turn-off angle increment according to the current deviation value, which will cause the actual turn-off angle of the converter to be too small, resulting in subsequent commutation failure during the recovery process

For the AC / DC hybrid power grid, continuous commutation failures caused by subsequent commutation failures may lead to DC system blocking, resulting in serious consequences such as power shortage of the AC system at the receiving end, equipment damage, etc.

Images