Optimization on Control Strategy of Tap Changer in HVDC Converter Transformer

doi:10.12204/j.issn.1000-7229.2021.02.002

Abstract

Abstract:

The on-load tap changer is important equipment to realize voltage and power regulation in HVDC system. In recent years, several serious faults arose during on-load tap changer adjustment process. To reduce the risk of tap changer failure, it is necessary to study the measures to avoid unnecessary adjustment of the tap changer. The control strategies of on-load tap changer of different types of HVDC converter stations are analyzed in this paper, and the reasons for the unnecessary continual adjustment of tap changer in some stations are revealed. On that basis, research on the optimizing of the operation mode, control parameters and control strategy is carried out, and three kinds of measures to reduce the adjustment times of the on-load tap changers are presented. Simulation models are set up to compare the effect of these measures. Finally, the feasibility of these measures is further verified by both simulation and site operation experience, the relative merits and application conditions for the suggested measures are also discussed.

Key words: HVDC system, on-load tap changer, continual adjustment, control strategy, real time digital simulation (RTDS)

CLC Number:

TM403.3

GUO Xianshan, LI Fengqi, RUAN Siye, ZHANG Jun, LIU Xinyang. Optimization on Control Strategy of Tap Changer in HVDC Converter Transformer[J]. ELECTRIC POWER CONSTRUCTION, 2021, 42(2): 9-11.

Figures/Tables 15

Fig.1 Control logic of tap changer in rectifier station

Fig.2 Flow chart of tap changer control in rectifier station

Fig.3 Control logic of tap changer in back-to-back DC inverter station

Fig.4 Flow chart of tap changer control in back-to-back DC inverter station

Fig.5 Control logic of tap changer in end-to-end DC inverter station

Fig.6 Flow chart of tap changer control in end-to-end DC inverter station

Fig.7 Simulation case of tap changer operation in traditional full-voltage operation mode

Fig.8 Simulation case of tap changer operation in reduced-voltage operation mode

Fig.9 Schematic diagram of tap changer to-and-fro continual adjustment

Fig.10 Simulation case of tap changer operation in optimizing DC voltage dead-band and asynchronous adjusting mode

Tab.1 Main circuit operation parameters of Tianzhong UHVDC project (original strategy)

Table 2 Main circuit operation parameters of Tianzhong UHVDC project(novel strategy)

Fig.11 Comparison of original strategy and DC dynamic voltage control strategy

Fig.12 Simulation case of tap changer operation in DC dynamic voltage control strategy mode

Table 3 Field test data of DC dynamic voltage control strategy in Zhaoyi HVDC project

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