Design of Energy Storage for Assisting Extraction Condensing Unit to Peak Regulation and Frequency Modulation

Abstract

Coupling energy storage system is one of the potential ways to improve the peak regulation and frequency modulation performance for the existing combined heat power plant. Based on the characteristics of energy storage types, achieving the accurate parameter design for multiple energy storage has been a necessary step to coordinate regulation. In this work, heat storage tank for peak regulation and flywheel energy storage for frequency modulation have been carried out, including the parameters design and performance evaluation for their charging (or discharging) rate and capacity, and the collaborative optimization of dual energy storage systems has been realized. First, the effects of increasing peak depth, load change rate (frequency modulation) range, and energy storage parameters are further analyzed. It is worth noting that the power curves of regional thermal and electrical loads would be adjusted according to the set requirements. Results showed that, the set rate of charge and discharge as well as the capacity of energy storage is conducive to improving the peak regulation depth of the system, and the peak regulation depth would reach its limit at 96.35 MW and 40.83 MWh in the calculation cases, respectively. On this basis, the cooperative regulation of dual energy storage can further increase the capability of peak regulation and frequency modulation. The extreme point is that when the charge and discharge rates are both 3 MW, and meanwhile the peak clipping coefficient, a self-defined parameter, reaches 22.34 MW. Furthermore, an example calculation is carried out to verify the reliability of the design method of energy storage parameter. The specific parameters set include the charging and discharging rate of energy storage tank equipment is 61.67 MW, and its capacity is 10.64 MWh, and the charging and discharging rate of flywheel energy storage equipment is 3 MW. The example results confirmed that there was only a very small error between the set results and the calculation results. Finally, the thermal-electric load region has been drawn to contrast the key roles of dual energy storage systems, which indicates that the heat storage tank can be used for peak regulation and flywheel energy storage for frequency modulation. Overall, the parameter design method for dual energy storage can meet the engineering requirements and provide a new direction for the subsequent parameter design of thermal power unit coupled energy storage system.