Assessing the Impact of Variable Renewable Energy on Generation Expansion Planning and System Reliability: A Case Study of Java Bali System

Previous studies show that integrating variable renewable energy (VRE) impacts system reliability and operational requirements. With Indonesia's target to increase the use of VRE to achieve a net zero emission target, an assessment of the impact of VRE on energy planning and system reliability is necessary. The Java-Bali System does not incorporate VRE in reserve margin or reliability calculation. However, the cost implications of VRE investments in system planning must be considered. Therefore, in this research, an assessment is conducted to evaluate the impact of VRE on power system planning and reliability by considering the investment effects of VRE in a generation expansion planning (GEP) while also assessing the system's reliability level. The GEP is conducted using a mixed integer linear programming (MILP) formula, followed by an evaluation of the impact of VRE on the reserve margin and investment costs. Based on the assessment of GEP for the Java Bali system, the electricity system has met the minimum reserve margin limit of 36.79% in 2030 without considering the contribution of the VRE power plant. In 2030, the VRE power plants of 3.1 GW are not considered in the reserve margin calculation. Building the 3.1 GW VRE power plant requires an investment of 1,440.8 million USD. If the VRE power plants are considered in the RM calculation, the RM becomes 44.67%. It shows the system overcapacity by adding the VRE to the RM calculation. Therefore, considering the VRE power plants in the RM calculation is crucial, and it is essential to obtain the firm capacity of the VRE power plant. The firm capacity shows the equivalent capacity of VRE PP in comparison to dispatchable power plants.