A novel thermal power unit with feedwater pump turbine driven by thermal energy storage system: System construction and performance evaluation

The rapid development of renewable energy power generation brings the strong demand of load regulation capacity for the coal-fired thermal power unit. This paper presents a novel approach to improving its operational flexibility with a feedwater pump turbine driven by a thermal energy storage (TES) system. The purpose of this study is to investigate the feasibility of the proposed system and evaluate its system performance. During energy charging process, some steam is extracted from hot reheat pipe to heat the TES system and reduce the power generation. During energy discharging process, the feedwater pump turbine is driven by the steam generated from the stored heat instead of extracting from the main turbine. Performance evaluation was conducted based on a model of a 660 MW supercritical thermal power unit. The results show that a low TES outlet steam temperature during the charging process should be employed and extracting water from the pipe between condenser and No. 8 heater during the discharging process should be adopted. The peak regulation range can be expanded from (198-660 MW) to (188.41-685.15 MW) without charging the boiler load rate. Hence, the proposed novel system is demonstrated to be an effective way for flexibility improvement of thermal power unit.