Frequency Stability Enhancement of Low-Inertia Large-Scale Power System Based on Grey Wolf Optimization

Sunghoon Lim,Jung-Wook Park,Soo Hyoung Lee,Donghee Choi,Chongqing Kang

doi:10.1109/access.2022.3146710

Abstract

The high penetration of converter-based distributed generations (DGs) to power system can give rise to the lack of rotational inertia while replacing the conventional synchronous generators (SGs), which provide the primary frequency reserve (PFR) in power systems. As the result, the decrease in PFR aggravates the frequency stability. To overcome this problem, the droop coefficients of governors in the remaining conventional SGs must be re-determined newly and properly. This paper proposes a new solution based on the grey wolf optimization (GWO) method to optimally select the droop coefficients of SG governors in the low-inertia large-scale power system due to the high penetration of renewables. The proposed solution is very effective for reducing the computational effort significantly, and it is able to recover not only the steady-state but also the transient frequency stability. To verify the effectiveness of proposed optimization solution based on the GWO method, several case studies are carried out on the practical Korea electric power system with the penetration of wind power plants of 4 GW.

Highlights

If these synchronous generators (SGs) are replaced with many converter-based distributed generations (DGs), and they always provide their maximum powers without inertia controls, it will cause a serious problem for the transient frequency stability in this low-inertia power system [1]–[5]
After the problem formulation to apply the grey wolf optimization (GWO) method, its implementation on a practical large-scale power system was accomplished in DIgSILENT PowerFactory® and MATLAB® based co-simulation framework
The results from several studies verified that the proposed optimization solution based on the GWO method improves the steady-state frequency stability, and the transient frequency stability most effectively and efficiently

Summary

INTRODUCTION

C. CONTRIBUTION AND PAPER ORGANIZATION This paper makes the new contribution by applying the heuristic optimization algorithm to optimize the droop coefficients of governors in remaining conventional SGs when the inertia of a large-scale power system becomes low due to the high penetration of wind power plants (WPPs). CONTRIBUTION AND PAPER ORGANIZATION This paper makes the new contribution by applying the heuristic optimization algorithm to optimize the droop coefficients of governors in remaining conventional SGs when the inertia of a large-scale power system becomes low due to the high penetration of wind power plants (WPPs) As the result, it can effectively recover both steady-state and transient frequency stability of a large-scale power system while keeping β constant. The high computational effort required for optimization in a large-scale power system is dramatically reduced with the proposed DIgSILENT PowerFactory® and MATLAB® based co-simulation framework applied with the GWO method.

FREQUENCY STABILITY

IMPLEMENTATION OF GWO METHOD

EVALUATION OF PERFORMANCE

CONCLUSION AND FUTURE WORK