Measurement-based dynamic load modelling using time-domain simulation and parallel-evolutionary search

© 2016 The Institution of Engineering and Technology.Conventional approaches for measurement-based load modelling uses measured voltage (V) as the input to calculate the load model output - P and Q powers. This assumes that the P and Q response is a function of V. In fact, there is an inherent interaction among the three variables (P, Q, and V) especially when motor load occupies a large proportion. With increased penetration of wind power, the fault-induced dynamic voltage response is becoming a serious concern given the low-voltage-ride-through (LVRT) requirement of wind turbines. This paper firstly shows that given different load model parameters, the V responses can vary significantly. Then, an improved method is proposed for more accurate measurement-based load modelling. The proposed method incorporates the V response into the load model output, therefore is able to accurately reflect the dynamic voltage trajectories. Given the load model parameters, the system responses of P, Q, and V are all simulated via time-domain simulations using industry-grade software, and problem is to search the load model parameters to minimise the fitting error between the simulated and measured system responses. A trajectory sensitivity index is used to identify the well-conditioned parameters, and a parallel-differential evolutionary algorithm is designed to solve the model.