Static Watt Compensator and Battery Energy Storage System for Frequency Stability Considering Smelter: A Comparison

The regulation of Indonesian Minister of Energy and Mineral Resources No. 4 of 2009 encourages many mining and mineral companies in Indonesia to build smelters. Electric arc furnaces used in the smelting process are non-linear loads that consume large amounts of power and change very quickly over time. The characteristics of electric arc furnaces that fluctuate rapidly may cause several problems such as system frequency instability. To compensate the intermittency of an electric arc furnace, a Static Watt Compensator (SWC) or Battery Energy Storage System (BESS) can be used. This paper discusses the comparison between the Static Watt Compensator and Battery Energy Storage System in terms of performance, sizing, and cost. The modeling and the simulation will be carried out with DIgSILENT PowerFactory, a power system analysis software. The performance of SWC and BESS will be compared by using the Integral Square Error (ISE) method. The results show that SWC maintains system frequency by absorbing active power and can only overcome the system's over-frequency condition, whereas BESS maintains system frequency by supplying or absorbing active power so that it can overcome both over-frequency and under-frequency conditions. However, the use of SWC increases system losses, which causes the total cost of SWC slightly higher than BESS.