Reactive voltage coordinated control method for extra-high-voltage DC converter station and near-field substation

Abstract

The invention provides a reactive voltage coordinated control method for an extra-high-voltage DC converter and near-field substation and belongs to the technical field of automatic voltage control ofpower systems. According to the method, when each automatic voltage control cycle arrives, whether the DC converter station is in a fault state after unipolar or bipolar blocking is checked, if the converter station is in the fault state, the emergency control of a near-field substation is performed; if the converter station is in a normal operation state, the operation trend of the converter station is determined, and corresponding control strategies are generated for different time periods where the active power of the converter station is located. According to the method, the coordinated control of extra-high-voltage and extra-high-voltage near-field substations is achieved, the repeated switching of reactive power devices in the near-site substation during the process of adjusting a converter station DC active power transmission capacity and the frequent switching of converter station reactive power devices are avoided, and the grid voltage stability and voltage quality are improved.

Description

technical field [0001] The invention relates to a reactive power and voltage coordinated control method of an ultra-high voltage direct current converter station and a nearby substation, and belongs to the technical field of automatic voltage control of electric power systems. Background technique [0002] Automatic voltage control (hereinafter referred to as AVC, Automatic Voltage Control) system is an important means to achieve safe (improved voltage stability margin), economical (reduced network loss), and high-quality (improved voltage qualification rate) operation of the transmission network. The AVC system architecture is based on the grid energy management system (EMS), which can use the real-time operation data of the transmission network to scientifically make the best reactive power and voltage adjustment plan from the perspective of overall optimization of the transmission network, and automatically send it to power plants, substations and subordinates The power g...

AI Technical Summary

Problems solved by technology

First, during the adjustment period of the active power transmission capacity of the converter station, the RPC system gradually switches the filter banks and capacitors according to the increase or decrease of the active power delivered by the converter station. Due to the large reactive power capacity of the filter, each switching will cause Large fluctuations in voltage, at the same time, the substation will follow its voltage optimization control target under AVC control, so the voltage is low before the filter (capacitor) in the converter station is put in, causing the substation to put in a capacitor (or remove the reactor), and in the converter station The high voltage after the filter (capacitor) is put in causes the substation to remove the capacitor (or put in the reactor), so there is a phenomenon that the reactive power equipment in the nearby substation is switched back and forth repeatedly during the adjustment of the DC active power transmission capacity of the converter station, which intensifies It reduces the voltage fluctuation in this area and affects the service life of reactive equipment in the substation

Second, after the adjustment of the active power transmission capacity of the converter station is completed and it enters into stable operation, the voltage of the converter station changes due to the AVC control switching capacitors and reactors in the nearby substation, and the reactive power exchange with the external AC system may occur The limit is exceeded and the RPC is triggered to switch the filter (capacitor) in the converter station, so the frequent switching of the filter (capacitor) in the converter station caused by AVC control occurs, which affects the safe and stable operation of the converter station

Third, when abnormal faults such as single-stage blocking or double-pole blocking of DC converter poles occur in the UHV converter station, due to the large change in the active power transmission capacity of the converter station during the fault process, the filter (capacitor) in the station during the fault process The adjustment capacity of the system may have been exhausted, and the voltage in this area may greatly exceed the limit after a fault. In traditional AVC, a fixed period (such as 5 minutes) is often used to issue the control of switching reactive power equipment to the substation adjacent to the converter station. Instructions, it is impossible to correct the bus voltage limit in this area in the shortest possible time

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