Optimal Sizing of a Photovoltaic/Battery Energy Storage System to Supply Electric Substation Auxiliary Systems under Contingency

Abstract

Electric substations (ESS) are important facilities that must operate even under contingency to guarantee the electrical system’s performance. To achieve this goal, the Brazilian national electricity system operator establishes that alternating current (AC) auxiliary systems of ESS must have, at least, two power supplies, and in the case of failure of these sources, an emergency generator (EG) must at least supply energy to the essential loads. In order to improve the availability of auxiliary systems, a microgrid with other sources, such as photovoltaic (PV) systems and Battery Energy Storage Systems (BESS), can be an alternative. In this case, an economical optimization of the PV/BESS system must be addressed considering the costs associated with the installation and maintenance of equipment, and the gains from the credits generated by the photovoltaic system in the net metering scheme. In this paper, the size of the BESS system was determined to supply energy to the load of auxiliary systems of an ESS, as well as a PV system to achieve a null total cost. Furthermore, multi-objective optimization using the genetic algorithm technique was employed to optimize the size of the hybrid PV/BESS to minimize the investment cost and time when the demand was not met. Simulations under different scenarios of contingency were allowed to obtain the Pareto frontier for the optimal sizing of a PV/BESS system to supply energy to AC auxiliary systems in an ESS under contingency.

Automatic Generation Control Ancillary Service Cost-Allocation Methods Based on Causer-Pays Principle in Electricity Market

“…In this case, the cost to be paid by the loads, calculated as the sum of ( 1) and ( 2), more than (10), which is the cost ISO pays to the AASS. This is because Load 2 absorbs t At the same time, ISO must pay AASS for the increased power and receive this cost from Load 1, which caused the increase in net demand.…”

“…In this case, the cost to be paid by the loads, calculated as the sum of ( 1) and ( 2), is more than (10), which is the cost ISO pays to the AASS. This is because Load 2 absorbs the increase in Load 1, reducing the system's overall supply imbalance.…”

“…If only Load 1 fluctuates, Load 1 must pay (1) to ISO. However, (10) is paid to ISO, not (1), which means that Load 1 must pay the difference to Load 2, and opportunity cost, which Load 1 pays to Load 2 C load 1,load 2 is calculated as:…”

“…Moreover, securing additional reserve power from conventional sources becomes increasingly difficult as their share diminishes. Exploring alternative solutions, such as harnessing new power system facilities like Energy Storage Systems (ESS), is a viable option but may entail substantial costs [8][9][10]. Consequently, addressing…”