Simulation Model Of Large-Scale Photovoltaic Power Station

Large-scale grid-connected photovoltaic station(LGPS) will change the power flow and voltage of grid, affecting the safety and stability of the power system. The change of load and short-circuit fault will alter output characteristics of PV station. Therefore, to study the interaction between PV station and power system, steady-state and transient analysis models of PV station should be established.Firstly, the paper describes the composition of LGPS and differences with distributed PV system. Listing the detailed power model and proposing three research points of power flow calculation model for generation unit. The impact of voltage and reactive power at the PCC caused by PV station is analyzed. According to voltage and reactive power control system of the station and the control principle of substation nine-zone diagram, to control the voltage and power factor at the PCC by inverters, SVG and transformers, corresponding strategies of voltage and reactive power control is proposed for PQ-type and PV-type PV station. The steady-state analysis simulation model for LGPS is built and the simulation results show that the proposed strategies are right and practical.Then, equipment selection and primary system design of a 30MW PV station is studied. Including defining array bracket installation and the type, capacity, number of series and parallel of PV cells, choosing filter and the type, capacity, control strategy of inverters, and deploying combiner boxes, DC distribution cabinets, AC distribution cabinets, transformers and collector lines. Considering the surrounding grid, primary system design scheme is determined by analyzing different grid-connected structure, boost methods and voltage level at the PCC.Finally, the detailed simulation model of LGPS in built after equipment selection and primary system design. According to equivalence principle and research content, the entirety model for transient analysis and DC equivalent model ignoring array and MPPT are given. Transient changes of the built model are studied by simulating short-circuit fault and irradiation change.