Electromagnetic torque analysis-based method for performance evaluation and optimisation of closed-loop CPS regarding small signal stability

• Published in: IET Cyber-Physical Systems: Theory & Applications Vol. 3; no. 4; pp. 187 - 193
• Main Authors: Sheng, Yibiao, Lin, Tao, Chen, Rusi, Chen, Baoping, Ding, Guili, Xu, Xialing, Xie, Chang, Liu, Lin
• Format: Journal Article
• Language: English
• Published: Southampton The Institution of Engineering and Technology 01.12.2018; John Wiley & Sons, Inc; Wiley
• Subjects: Closed loop systems; closed-loop CPS; closed-loop cyber-physical system; closed-loop system; Control stability; cyber-physical systems; Damping; electromagnetic torque analysis method; electromagnetic torque analysis-based method; electromagnetic torque coefficients; Feedback; Frequency stability; inter-area low-frequency oscillations; optimisation; Optimization; Performance evaluation; power system control; power system measurement; power system stability; small signal stability; Smart grid; Special Issue: Cyber Physical Power Systems: Advanced Intelligent Technologies and Applications; time delay; Time lag; torque; two-area four-machine physical system; typical cyber system; WADC control parameters; wide-area damping controller; wide-area measurement system; power system stability; power system measurement; electromagnetic torque analysis method; smart grid; electromagnetic torque analysis-based method; small signal stability; wide-area measurement system; torque; time delay; time-delay; typical cyber system; damping; wide-area damping controller; inter-area low-frequency oscillations; closed loop systems; cyber-physical systems; optimisation; WADC control parameters; closed-loop cyber-physical system; two-area four-machine physical system; electromagnetic torque coefficients; power system control; closed-loop CPS; closed-loop system
• ISSN: 2398-3396; 2398-3396
• DOI: 10.1049/iet-cps.2018.5033

Low frequency oscillation occurs frequently in the smart grid, which threatens the security and stability of the physical system. Wide-area damping controller (WADC), which belongs to cyber system, can effectively suppress inter-area low frequency oscillations and improve the small signal stability of the closed-loop cyber-physical system (CPS). However, with the introduction of global signals, time delays of communication are inevitable. Considering that, this paper deduces the general mathematics expression among electromagnetic torque coefficients, WADC control parameters and time delays, which makes it possible to analyse the influence mechanism of time delay on small signal stability. Based on these analysis, on the one hand, the time-delay small signal stability region is established to evaluate the operation state of closed-loop CPS, on the other hand, if small signal stability is not achieved due to the measured time delays, optimisation scheme is proposed to carry out WADC control parameters coordination to optimise small signal stability of the closed-loop system. Finally, taking two time delays as example, this study verifies the effectiveness and advantages of the proposed method by comparing the closed-loop system performance considering two time delays with the cases of considering singe time delay and without time delay.