Risk assessment of photovoltaic system based on cumulant method and mixed copula

With the gradual integration of new energy resources such as photovoltaics into the power system, randomness and volatility in its operation become increasingly prominent. The traditional power flow calculation cannot accurately assess the operational risk of the power system. Additionally, there is a certain correlation among the outputs of each photovoltaic (PV) power station, and further study is needed for the risk assessment of power systems with PV power stations. This paper proposes a probabilistic power flow calculation method based on cumulant method and mixed Copula. The Cornish–Fisher series expansion method obtains the probability density function and comprehensively measures probability and severity. Node voltage and branch power flow limit indexes are established to evaluate the system operation risk. Testing the method in the IEEE34 node system verifies the impact of PV access on operational risk. Compared with the Monte Carlo method, the analysis examines the effects of PV output correlation on system operation characteristics. The results demonstrate that the proposed method efficiently and accurately assesses the risk of PV systems.