Fault Current Limitation Roadmap to Anticipate the Problem of High Fault Currents in Indonesian Java-Bali Power System

Power system expansion is carried out to meet the load growth. Expansion results in increasing fault currents and, in Java-Bali power system, the increases are projected to exceed the short circuit capabilities of the existing circuit breakers as the protective equipment. There are three alternatives going to be optimized in solving this problem: network reconfiguration, installations of fault current limiters, and upgrades of circuit breakers. This paper presents the anticipation roadmap of Java-Bali power system expanded based on PT PLN Electricity Business Plan 2021–2030. The grid code constraints include loading, voltage level, and 500 kV critical clearing time, both in the normal and 500 kV line N-2 contingency conditions. Firstly, the network reconfiguration is held; that is, network splitting operations in the 150 kV grid and bus splitting operations in the 500 kV grid. The number of loops is minimized so that the system's effective impedance is increased and, thus, fault currents become lower. Next is to install series fault current limiters (FCLs) to again increase the system's effective impedance and decrease the fault currents. Nevertheless, FCLs introduce unwanted side effects such as voltage drops, increases in grid losses and decreases in stability. Thus, these parameters need to be considered as another engineering constraints. Finally, circuit breakers whose breaking capacities are lower than the fault currents in associated substations are upgraded. The simulation result performed using DIgSILENT PowerFactory explains that the anticipation roadmap ensured no fault current exceeds the short circuit capabilities of circuit breakers in the recommended configuration.