A new short-circuit calculation method of power system with photovoltaic power sources

Abstract

A large number of photovoltaic power sources connected to the grid will increase short-circuit current level of power system, and its fault transient process will change the fault characteristics of power grid. In this paper, the equivalent models of transient and steady state faults are obtained, by analysing the full current expression of photovoltaic power sources and its current characteristics in different fault stages. Based on the superposition theorem, the short-circuit current calculation method of power system with photovoltaic power sources is proposed. Finally, the effectiveness of the proposed method is verified by the analysis of actual power grid calculation examples, and the results can be used for power grid planning and relay protection setting.

A state‐space average model of a three‐level PV inverter for transient short‐circuit currents analysis

“…s ij1 are the fundamental components of s ij . Substituting Equations (18) into Equations ( 9), ( 15), (16), and ( 17), we obtain the proposed average model of a three-phase three-level PV inverter as Equations from (19) to (22).…”

“…To better understand transient behaviours of PV short-circuit currents, on the analogy of conventional synchronous generator short-circuit current characteristics, a short-circuit current is divided into a DC transient component and an AC steadystate component, and as a result, the equivalent models of transient and steady-state faults are obtained [19,20]. However these researches lack theoretical basis.…”