高压直流系统低功率运行时的无功控制策略

Proposal on Reactive Power Control of HVDC System During Low Power Transmission

直流系统低功率运行时受端无功严重过剩,电网稳态电压偏高问题十分严重。对直流系统低功率运行时无功控制策略进行探讨,推导了无功消耗、关断角、换相角、直流电流等变量之间相互关系,计算受端换流站关断角和换流变分接头调节措施对直流无功功率消耗的影响,提出利用直流系统无功消耗的非线性,提高最小关断角可以吸收多余无功,有效解决直流系统低功率运行时的交流电网电压升高问题。

There are three conditions making the HVDC power transmission system operated in low power transmission： putting generation units at sending end into operation, seasonal power generation of upstream hydropower station and a period after putting HVDC system into operation. When HVDC transmission system is operated in low power operation condition, serious surplus of reactive power will occur in receiving end and it makes system voltage deviating from its normal value and the obvious voltage rise appears at the receiving end. The reactive power control strategy under low power transmission of HVDC system is discussed and the relations among such variables as reactive power consumption, extinction angle, commutation angle and DC current are derived, and the impacts of the adjustment of the extinction angle of converter station at receiving end and the adjustment of on-load tap changer of converter transformer on reactive power consumption in HVDC system are calculated, and then it is proposed that according to the nonlinearity of reactive power consumption in HVDC system the voltage rise problem caused by the low power transmission of HVDC system can be effectively solved by increasing the minimal extinction angle to absorb the excrescent reactive power.