Measurement and Modeling of Delays in Wide-area Closed-loop Control Systems

This paper aims to study the measurement and modeling methods for delays in wide-area closed-loop control systems (WACS). The delays are classified into communication delays and operational delays based on the information flow of WACS. For communication delays, an affine evaluation model is proposed based on previous studies, and this model is verified by the measured communication delays of the Guizhou Power Grid in Southwest China. For operational delays, a real time digital simulator (RTDS) hardware-in-the-loop measurement method is developed, and the measured operational delays are obtained and analyzed. Finally, an estimation method for the closed-loop delay in actual WACS is proposed, in which the uplink and downlink communication delays are modeled as constants and the operational delay is modeled as a normal distribution. Consequently, the closed-loop delay follows a normal distribution with the calculated parameters by combining the communication delays and operational delay. The measurement results and analysis presented in this paper are important for the development and applications of WACS.