光伏集中并网电压约束下的准入容量与电压波动的评估方法

Penetration Capacity Under Voltage Constraint and Evaluation Methodology of Voltage Fluctuation Caused by Centralized Grid Connection of Photovoltaic Power

大容量光伏集中并网必定会对整个配电网特别是并网点的电压造成一定的影响,而光伏出力的随机性也会引起电压的随机波动。为此,建立了光伏集中并网后引起并网点电压偏差的数学模型,导出了以电压偏差不越限为约束的光伏准入容量,定义了能够全面反映母线电压波动情况的4项指标,即分布重心、离散度、偏度和峰度,提出一种评估光伏并网下电力系统电压波动状况的方法。基于光伏出力的随机模型在PSCAD中建立了符合实际情况的光伏电站组件,并以单电源链式配电网为例验证了上述指标的准确性和有效性。最后将所提指标和方法用于某地区含光伏电站电网的电压波动程度的评估,结果表明该指标和方法可为光伏电站并网点的优选提供参考依据。

Centralized grid connection of large capacity photovoltaic power undoubtedly causes certain influence on voltage in distribution network, especially at point of common coupling（PCC）, and random fluctuation of photovoltaic power output leads random voltage fluctuant in power grid. Therefore, a mathematical model of PCC’s voltage deviation under centralized grid connection of large capacity photovoltaic power is constructed and PV penetration capacity under voltage constraint is derived. Four indexes are defined to fully reflect bus voltage fluctuation, namely distribution center, discrete degree, skewness and kurtosis and accordingly a method assessing voltage fluctuation of power system is put forward. Based on stochastic model of photovoltaic output, photovoltaic power station module in accordance with actual situation is established in PSCAD. A single power supplied chain distribution network is taken as an example to verify the accuracy and validity of these proposed indexes with PSCAD simulation. Finally, the proposed indexes and method are applied to evaluate the voltage fluctuation of a regional power grid with photovoltaic power station. The results show that the evaluation indexes and corresponding method can provide instructive reference for PCC selection.