考虑网络损耗的直流近区风电场集电参数等值建模

Research on equivalent modeling of collecting parameters of DC near-field wind farms considering network losses

直流近区风电场受直流输电特性的交互影响,极易出现并网点暂态过电压问题,风电场集电参数对过电压水平的影响不容忽视。在此背景下,针对直流近区风电场的集电参数等值建模问题,结合暂态过电压功率特性,首先提出一种考虑损耗的风电场集电网络等值建模方法,然后定量化研究风电场内机组过电压水平受集电参数的影响,最后以实际电网为例,仿真风电场汇集的直流外送系统两次换相失败,分析其暂态过电压特性及风电场等值模型动态输出特性。结果表明:并网点过电压时远端机组电压变化幅度小于近端机组,相差为额定电压的2.5%左右,因此,必须考虑风电场集电参数等值;考虑集电参数损耗的等值模型与实际风电场的功率损耗、平均电压特性基本保持一致,具有实际应用价值。

The characteristics of DC power transmission have reciprocal effects on wind farms and it would possibly give rise to the transient overvoltage.The influence of collector parameters on overvoltage level in wind farms cannot be ignored.Under this background,for the modeling problem of wind farm near the DC region,this paper firstly proposes an equivalent modeling method considering power loss of collector networks by combining the power characteristics of transient overvoltage.And then,the effect of collector parameters on the generator terminal overvoltage can be quantified.Finally,the actual grid is included as an example.The characteristics of transient overvoltage and output characteristic of equivalent model are analyzed by simulating the case of two continuous commutation failures of HVDC system.It is shown that the variation of generator terminal voltage in the far-end wind turbines is lower than that of the near-end,and the difference is about 2.5%compared to the rated voltage.Therefore,it is necessary to consider the collector parameter equivalence of wind farms.Meanwhile,the power loss and average voltage of this equivalent wind farm model in this paper are fairly remain consistent with that of actual model,so that it has a certain practical application value.