Time-based Equivalent Method for Reactive Power Regulation Capacity of Grid-connected Photovoltaic Plant

The existing equivalent methods for reactive power regulation capacity of grid-connected photovoltaic(PV) plant do not take into account the voltage security constraints in the plant and the impacts of random fluctuations of grid-connected voltage and photovoltaic output, which makes it hard to meet the requirements of actual engineering. For this reason, a time-based equivalent method for reactive power regulation capacity of grid-connected PV plant is proposed, which can provide an effective decision-making basis for actual engineering management. Firstly, under the given gate voltage and PV output, and with consideration of the static var generator within the PV plant, the reactive power regulation capacity of the PV unit and the upper & lower limits of the reactive power regulation range, an optimal equivalent method for maximum gate reactive power regulation capacity of PV plant is proposed to determine the relationship between the gate reactive power regulation capacity of the PV plant and its active output and gate voltage. Secondly, considering the time period characteristics of the gate voltage and PV output fluctuations, the time-based equivalent scheme for reactive power regulation capacity of PV station is realized through the time period fusion strategy for fluctuation thresholds of similar days. Finally, the simulation analysis of an actual PV plant verified the effectiveness of the proposed method.