Abstract
The utilization of Energy Storage Systems (ESS) for improving the frequency response of a low inertia power system is investigated in this article. Substantial wind power penetration is causing the replacement of conventional synchronous generators in several power systems. Variable speed wind machines traditionally do not contribute to frequency regulation without additional control strategy. As a result, a wind dominated power grid may have inadequate inertia and governor responsive reserve. In such situation, a large contingency may yield undesirable Rate of Change of Frequency (ROCOF) and frequency deviation. To overcome this problem, deployment of ESS, namely, Superconducting Magnetic Energy Storage (SMES) and Battery Energy Storage System (BESS) can be a worthwhile solution. Since these devices are costly, their appropriate sizing and operational approach are crucial. Therefore, in this paper, analytical expressions are derived to find the minimum ratings of SMES and BESS. To this end, system frequency deviation, ROCOF, inertial response and governor response are taken into account. Also, a coordinated operational strategy is proposed to retain frequency response adequacy and minimize under-frequency load shedding where SMES is triggered when system ROCOF supersedes a certain limit and BESS is activated due to system frequency surpassing a preset threshold. The performance of the proposed strategy is explored in a low inertia network under substantial wind penetration considering several different wind penetration levels. Also, the results are validated against two existing approaches. Simulation results reveal that the proposed methodology considerably enhances the frequency response in various operating conditions.
Highlights
In recent times, traditional synchronous generators are being decommissioned in many power systems
Energy Storage Systems (ESS) RATINGS Using the proposed methodology, the ratings of Superconducting Magnetic Energy Storage (SMES) and Battery Energy Storage System (BESS) can be evaluated for any case studies
Extensive investigations are carried out to explore the roles of SMES and BESS for improving the frequency response of a low inertia grid
Summary
Traditional synchronous generators are being decommissioned in many power systems. Generator: DFIG) and type IV (Full-Scale Converter: FSC) machines These variable speed machines are isolated from the grid through power electronic converters [2]. They generally do not provide inertia and governor response ( known as primary frequency response) unless additional control strategy is implemented [3]. Situations can arise where a system has substantial wind penetration while it imports bulk amount of power through high voltage AC (HVAC) interconnection from adjacent grid. In such a condition, only a few VOLUME XX, 2017
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