直流闭锁故障下风电并网功率和直流输送功率的耦合关系分析

Coupling Relationship Between Wind Power Grid-connected Power and DC Transmission Power with DC Block Fault

中国一次能源和负荷成逆向分布,新能源基地集群通过特高压直流群外送,新能源高占比电网中风电和直流耦合关系复杂。首先,建立电网分析模型,研究风电和直流在电网频率、电压方面的耦合关系。其次,根据最大频率偏差耐受能力,计算风电和直流在频率方面的耦合关系。再次,根据直流闭锁故障后风电暂态过电压总脱网量约束,推导风电并网点的暂态压升,计算暂态压升和脱网量的关系,得到直流和风电在暂态过电压方面的耦合关系。理论计算结果表明:风电和直流呈负相关性。根据2020年西北电网青豫直流和近区风电并网功率的仿真结果,验证了理论推导的正确性。

China's primary energy production bases and load centers are inversely distributed and the renewable energy of the production base cluster is delivered through UHVDC cluster,so the coupling characteristics of wind power and DC are complex in the power grid with high renewable energy penetration.Firstly,an analytical model is established to study the coupling relationship between wind power and DC in power grid frequency and voltage.Secondly,according to the maximum frequency-deviation tolerance of power grid,the frequency coupling characteristics of wind power and DC are calculated.Thirdly,according to the constraint of the total trip-off of wind power transient overvoltage under DC blocking fault,the wind power transient voltage rise at the grid-connected point is derived,and the relationship between the transient voltage rise and the trip-off quantity is calculated.The coupling relationship of transient overvoltage between DC and wind power is thus obtained.Theoretic analysis shows that wind power is negatively associated with DC,and simulation of the relationship between the transmission capacity of the Qinhai-Henan DC project and the grid-connected power of adjacent wind power based on the data of the Northwest China Power Grid in 2020 verifies the correctness of the theoretical derivation.