Hybrid Energy Storage Assisted Frequency Regulation for the Thermal Power Plants

To address the problems of slow power regulation speed, insufficient control accuracy, and delayed response of conventional thermal power units in automatic generation control operation, which makes it difficult to accurately and rapidly track grid frequency regulation commands and may lead to regulation delay, regulation deviation, and reverse regulation, a coordinated frequency regulation scheme combining thermal power units and energy storage systems is proposed in this paper. A hybrid energy storage system composed of supercapacitors and lithium iron phosphate batteries is introduced to provide auxiliary support for the frequency regulation process of thermal power units. On this basis, a hierarchical coordinated control strategy based on system frequency deviation and power command is designed. Taking a thermal power plant with two 660 MW supercritical coal fired generating units as the research object, a combined thermal power and energy storage frequency regulation model is established, and simulation analysis and engineering application verification are carried out. The results show that, after applying the proposed coordinated frequency regulation strategy, the integrated output of the units can track AGC frequency regulation commands rapidly and accurately. The tracking correlation coefficient between the combined output and the AGC commands is increased to above 0.99, while overshoot and response lag during the frequency regulation process are significantly reduced, and the operational stability of the system is markedly enhanced. Meanwhile, the comprehensive frequency regulation performance index kp is improved from 0.8 to 1.63, indicating a substantial enhancement in overall frequency regulation performance. The study demonstrates that the proposed coordinated frequency regulation technology can effectively compensate for the insufficient frequency regulation capability of conventional thermal power units and has practical engineering value for improving the frequency regulation performance of thermal power units and ensuring the safe and stable operation of power systems.