基于机组电压支撑效果的直流近区火电最小开机方法

Minimum startup method of a DC near-field thermal power unit based on a unit voltage supporting effect

随着大规模新能源集中接入及直流送出规模的提升,送端电网面临暂态过电压和事故后稳态过电压等电压问题。基于送端电网特高压直流运行特性,全面评估了火电机组暂态稳定、潮流组织等安全性及充裕性作用。在此基础上,首先分析了火电机组对多回直流换流站静态电压支撑效果,通过故障下机组无功出力随时间变化积分获得直流预想事故集下动态电压支撑效果。结合静态及动态电压支撑效果,确定直流配套机组最优开机顺序,兼顾直流稳控切机容量。最终确定直流近区最小开机方式,并以实际电网算例进行验证。

With the centralized access of large-scale new energy sources and the increase of DC output,the sending power grid is faced with transient overvoltage and steady-state overvoltage after an accident.The safety effect including transient stability,power flow organization and adequacy effect are comprehensively evaluated based on the UHVDC operating characteristics of the sending power grid.On this basis,first,the supporting effect of a thermal power unit on the static voltage of a multi-circuit DC converter station is analyzed.Then the dynamic voltage supporting effect of the DC predictive fault set is obtained by integrating the unit reactive power over time under the fault.Combined with the supporting effect of the static and dynamic voltage,the optimal startup sequence of the DC supporting unit is determined,and the DC stable control tripping capacity is taken into consideration.Finally,the minimum startup method of the DC near-area is determined and verified by an actual grid example.