A Study on Load Dispatching Methods in Load Frequency Control with Battery Energy Storage Systems

―Comparison of Proportional-dispatching and Target-period-sharing Schemes―

Abstract

This paper examines the performance of two representative schemes—i.e., proportional-dispatching and target-period-sharing schemes—for load frequency control (LFC) of a power system, in which battery energy storage systems (BESSs) and thermal power plants are used for LFC. The target-period-sharing scheme has been recently proposed for LFC with BESS while the proportional-dispatching scheme has been widely used in LFC with thermals. However, few researches compare the performance of the two schemes. The paper examines their performance with spectral analysis techniques through simulation studies on the AGC model published by IEEJ—i.e., AGC30. The results show that the target-period-sharing scheme is preferable to the proportional-dispatching scheme when an appropriate time constant is chosen for a filter in the target-period-sharing scheme. The approximate time constant depends on the response characteristics of the LFC-regulated plants. On the other hand, regulation capacity should be carefully examined for the slow-response LFC-regulated plants in the target-period-sharing scheme because limiters in the control circuits tend to become active for the plants in the scheme.