Flexible DC power transmission system fault ride-through voltage margin control method and device

Abstract

The invention provides a flexible DC power transmission system fault ride-through voltage margin control method and device. The method comprises the following steps: determining a constant DC voltage end outer loop current amplitude limiting value change rate and a constant frequency control end outer loop current amplitude limiting value change rate; determining a constant direct-current voltage end amplitude limiting value and a constant frequency control end amplitude limiting value; according to the method, the output value of a constant direct current voltage end inner loop current controller and the output value of a constant frequency control end inner loop current controller are determined, and the alternating current side fault ride-through of the flexible direct current power transmission system is controlled, so that the fluctuation is greatly reduced, and the fault recovery time is shortened; the flexible DC power transmission system control is dynamically optimized in real time to adapt to the disturbance of the passive AC system, the AC transient process is stabilized, the safe operation of the flexible DC power transmission systems at two ends during the passive AC system transient fault period and in the fault recovery process can be ensured, and the DC control characteristics can be dynamically adjusted according to the fault characteristics. And alternating-current fault ride-through is realized.

Description

technical field [0001] The invention relates to the technical field of flexible direct current transmission, in particular to a method and device for controlling a fault ride-through voltage margin of a flexible direct current transmission system. Background technique [0002] Due to its excellent control characteristics, flexible DC transmission is especially suitable for the application scenario of connecting passive AC systems. When one end of the two-term flexible direct transmission system is connected to the passive network, according to the control principle of the flexible direct transmission system, the active power control target of the flexible direct transmission system connected to the passive AC system end needs to control the frequency of the passive AC network, so the active power control at the other end The target is a DC voltage. When a temporary fault occurs in the AC system at both ends and during the recovery process after the fault, the transient proc...

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Problems solved by technology

However, when a fault occurs in the flexible HVDC system, under large dynamic conditions, the d-axis reference value of the inner loop current controller obtained by the fixed-value limiting strategy will vary greatly, and this limiting will hinder the realization of the reference value. As a result, the tracking time of the inner loop current controller to the reference value is lengthened, resulting in large fluctuations in the flexible direct current transmission system, and a long fault recovery time

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