A Methodology for Provision of Frequency Stability in Operation Planning of Low Inertia Power Systems

Abstract

Along with the increasing share of non-synchronous power sources, the inertia of power systems is being reduced, which can give rise to frequency containment problems should an outage of a generator or a power infeed happen. Low system inertia is eventually unavoidable, thus power system operators need to be prepared for this condition. This paper addresses the problem of low inertia in the power system from two different perspectives. At a system level, it proposes an operation planning methodology, which utilises a combination of power flow and dynamic simulation for calculation of existing inertia and, if need be, synthetic inertia (SI) to fulfil the security criterion of adequate rate of change of frequency (RoCoF). On a device level, it introduces a new concept for active power controller, which can be applied virtually to any power source with sufficient response time to create synthetic inertia. The methodology is demonstrated for a 24 h planning period, for which it proves to be effective. The performance of SI controller activated in a battery energy storage system (BESS) is positively validated using a real-time digital simulator (RTDS). Both proposals can effectively contribute to facilitating the operation of low inertia power systems.

RoCoF-Minimizing H₂ Norm Control Strategy for Multi-Wind Turbine Synthetic Inertia

“…Among current closed-loop SI approaches, no particular VOLUME 4, 2016 attention is paid to controller parameter choice to maximize performance. These approaches basically propose a control law that represents the dynamic limitations on the amount of kinetic energy that can be stably withdrawn from the VSWT; for example, [10] proposes an energy constraint to a linear controller to account for the dynamic limitations with a stabilising low-pass filter. Similarly, in [11], a simplified constraint representing the feasible choice of a SI linear controller is added to an economic operation formulation.…”

A Study on Frequency Stability and Primary Frequency Response of the Korean Electric Power System Considering the High Penetration of Wind Power

“…In particular, the high penetration of wind power decreases the system inertia and the amount of primary frequency reserve, adversely impacting frequency stability. Moreover, when analyzing the frequency stability, frequency nadir (f nadir ) and settling frequency (f set ) are considered for the dynamic and steady state, respectively [4][5][6]. In order to maintain the frequency stability in the Korean electric power system, these two indices need to be above 59 Hz and 59.8 Hz to prevent under-frequency load shedding relay and activate automatic generation control (AGC), respectively.…”