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 the 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 are conducive to improving the peak regulation depth of the system, and the peak regulation depth would reach its limit at 96.35MW and 40.83MWh 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 3MW, and meanwhile the peak clipping coefficient, a self-defined parameter, reaches 22.34MW. 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 61.67MW, and its capacity is 10.64MWh, and the charging and discharging rate of flywheel energy storage equipment is 3MW. 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.

The increasing depletion of fossil energy and the gradual aggravation of environmental pollution have increased the necessity of renewable energy applications. However, the intermittent characteristics of renewable energy power generation need to increase the flexibility of the original coal-fired power unit for balancing the supply and demand of the power system. In this work, two 350 MWe condensing units (CUs) were taken as examples and the thermodynamic simulation models were built by the ebsilon software to evaluate their technical and economic characteristics. At the same time, the system is coupled with heat pump (HP) and backpressure turbine (BT) for heating. Among them, the rated steam intake of HP is 194.9 t/h, and the rated steam intake of BT is 214.5 t/h. Results show that under the same requirements, the energy consumption with the backpressure turbine priority principle (BTtlp principle) is smaller than that with the heat pump priority principle (HPtlp principle). However, under the same thermal load conditions, the electrical load with the HPtlp principle can drop lower than that with the BTtlp principle. Meanwhile, there is an optimization interval for the output distribution of HP and BT. From the energy current diagram, it can be found that under the design main steam and given thermal load condition, the power generation efficiency of coupled mode is 0.74% more than that of HP mode and is 1.93% more than that of direct mode, while under the given thermal and electrical load condition, the system’s boiler output with direct mode is 3.37% more than that with HP mode and is 5.34% more than that with coupled mode. This provides a theoretical basis for the subsequent comprehensive evaluation of heating reformation.