Fast control method of fault island containing flexible DC

Abstract

The invention discloses a fast control method of a fault island containing flexible DC. A control strategy execution scheme is formed through offline simulation calculation for the condition of an interconnected network of which regional network powers are connected with other power networks through AC and DC transmission channels separately; an offline control strategy is divided into an emergency control strategy and a non-emergency control strategy to correspond to control methods of different flexible DC; the strategy which is obtained through offline calculation in advance is searched according to frequency and frequency variation characteristics when the fault island is generated, execution is confirmed, a frequency and a frequency variation are continuously judged, and real-time complement can be carried out on an action result of a security and stability control device in a power system; and the stability of an island system is finally restored. The fast control method has the advantages that a flexible DC control method is directly determined in a manner of using an offline strategy searching scheme, the sampling calculation amount is small, judgment is fast and the control efficiency is high, thereby improving the frequency stability and the operation economy of the fault island.

Description

technical field [0001] The invention belongs to the technical field of power system operation control, and in particular relates to a fast control method for fault islands with flexible direct current. Background technique [0002] Flexible direct current transmission (flexible direct current) technology uses fully controlled power electronic devices, which has many advantages such as fast power flow control, dynamic reactive power support, multi-port coordinated operation, and prevention of expanded fault range. Multiple regional power grids are connected through AC and DC transmission to form an interconnected power grid. When an important section fails, regional power grid voltage and frequency stability problems will occur, which seriously threatens the safe and stable operation of the power grid. After the system stability is damaged, it is usually necessary to cut the machine (or load) by the stability control device to ensure the stable operation of the system. After...

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Problems solved by technology

Aiming at the connection mode that the regional power grid is connected to other power grids through AC and DC transmission channels respectively, when the AC transmission channel is interrupted to form a regional island power grid, the power shortage will cause the island to lose stability. The connection mode of the transmission channel and other power grids is formed through offline simulation calculations to form an offline control strategy. At the moment of the fault island, the offline control strategy obtained by offline calculation is searched according to the frequency and frequency change rate, and the flexible DC fast emergency control and accurate The non-emergency control is organically combined. Before the second and third lines of defense of the safety and stability control system operate, the flexible DC has the safe and fast power flow adjustment and reversal functions that conventional DC does not have. Then the flexible DC can dynamically adjust the islanding frequency in two directions. The characteristics of the system continue to make up for the execution deviation of the safety and stability control system, and finally restore the stability of the island system

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