Design of a robust PID-PSS for an uncertain power system with simplified stability conditions

Vijaya Lakshmi A.S.V,Ramalinga Raju Manyala,Siva Kumar Mangipudi

doi:10.1186/s41601-020-00165-9

Abstract

In a deregulated power system uncertainty exists and lack of sufficient damping can lead to Low Frequency Oscillations (LFO). The problem can be addressed using robust Power System Stabilizers (PSS). In this paper, an optimal procedure to design a robust PID-PSS using interval arithmetic for the Single Machine Infinite Bus (SMIB) power system is proposed. The interval modelling captures the wide variations of operating conditions in bounds of system coefficients. In the proposed design procedure, simple and new closed loop stability conditions for an SMIB interval system are developed and are used to design an optimum PID-PSS for improving the performance of an SMIB system. The optimum PID-PSS is attained by tuning the parameters using the FMINCON tool provided in MATLAB. The robustness of the proposed PID-PSS design is validated and compared to other notable methods in the literature when the system is subjected to different uncertainties. The simulation results and performance error values show the effectiveness of the proposed robust PID-PSS controller.

Highlights

Synchronous generators are equipped with high gain AVRs to enhance stability margins
To overcome the above issues, this paper presents a systematic procedure to develop simple and new stability conditions for an interval system
6 Conclusion A simple robust PID-Power System Stabilizers (PSS) design methodology is proposed to enhance the dynamic stability of an Single Machine Infinite Bus (SMIB) system for a wide range of operating conditions

Summary

Introduction

Synchronous generators are equipped with high gain AVRs to enhance stability margins. A controller design employing interval systems uses the following methods: 1) Eight extreme polynomials; 2) The Interval Routh Hurwitz criterion; and 3) Image set polynomials for 1024 operating conditions Even though these methods exhibit robust stability, they require high computational effort. The PID-PSS parameters are obtained using the newly developed stability conditions for interval systems, and to ensure the robust performance of the proposed PID-PSS, an objective function at a nominal operating point is defined. New necessary and sufficient conditions for SMIB system are developed to design the controller parameters of the robust PID-PSS for a specified range of operating conditions. For order n = 4 the stability conditions for the SMIB power system are given by: aaaþ01−þ0≥aaa2þ3−0−00:4;6a5þ15≥ a1− Using these stability conditions the robust PID-PSS controller for the SMIB system under large uncertainty is developed .

Case study I

Simulation results and discussion

Conclusion