Analysis of Short-circuit and Protection Failure Risk Considering Random Output of Distributed Photovoltaics

Distributed photovoltaics (DPV) will increase or shunt the fault current as a branch of the power supply. The random outputs of DPV will also cause a random distribution of fault current, while the breaking capacity of the breaker and the setting value of the current protection is pre-set value, and cannot flexibly change, so DPV will bring a certain degree of influence on the breaking margin and the sensitivity of protection. This paper makes probability distribution calculating model of fault current containing DPV, and takes IEEE 33-node system as an example, simulated the probability distribution of fault current at different penetration of DPV. Finally, from the two indicators of the breaking margin of breaker and the sensitivity of protection, analysed the protection failure risk after the access of DPV.