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Many power plants have been transformed and operated using low‐pressure cylinder near‐zero output (LP‐ZO) technology in China to make way for or provide necessary guarantees for renewable energy power generation. This research focuses on utilizing numerical simulation tools to improve the operational economy of units with LP‐ZO. The LP‐ZO thermodynamic and energy‐consumption model of a reference plant is established, and the momentum particle swarm optimization method is used to optimize the unit operations. Moreover, a model to determine the economic operational range of the combined heat and power plant with LP‐ZO is proposed. The results show that the LP‐ZO mode operations of the unit can reduce the minimum peak shaving rate and improve the flexibility of operations. The energy efficiency of the LP‐ZO mode is increased due to the recovery of a significant portion of the cold source losses. However, the irreversible exergy loss caused by large temperature difference heat exchange reduces the exergy efficiency of the unit. After operational optimization, the reference plant can save approximately 68.15 t d−1 of coal and reduce carbon dioxide emissions by about 27 t tce−1 d−1. This study provides an operating approach to the CHP plant with LP‐ZO unit in enhancing flexibility and economy. [ABSTRACT FROM AUTHOR]

With the development of new-power generation sources, the difference between maximum and minimum power requirements from a power grid is growing. However, the peaking power installed capacity, such as pumped-hydro energy storage and gas-fired power, is too small to meet the peaking regulation requirements. Chinese coal-based energy resources structure determines coal-fired power plants to be the main source of power. This means that coal-fired power units will need to undertake more peak shaving tasks for a long period of time. In this paper, we provide an overall review of China׳s coal-fired power units׳ peak regulation with a detailed presentation of the installed capacity, peak shaving operation modes and support policies. High energy-consumption problems, environmental pollutants and safety barriers when coal-fired power units run in low-load operation are noted from the power generation perspective. Some policy recommendations are given to solve the peak shaving problem to some extent and to ensure the sustainable development of the power energy system. [ABSTRACT FROM AUTHOR]

• Operation modes were considered in energy consumption of a CHP plant. • The heat rate was obtained considering two units operating in parallel. • Optimization model based on the energy consumption was established. • 304.44 kJ·kWh−1 can be saved for the reference CHP plant. Optimizing thermal–electric load distribution toward combined heat and power (CHP) units can improve the efficiency of thermal power plants. Here, a thermal–electric load distribution method is proposed based on the energy consumption characteristics of CHP plants. The influence of operation modes on the energy consumption characteristics has been considered. Based on the energy consumption characteristics, the influence of load distribution on the heat rate is expounded considering two units operating in parallel. Firstly, a 600 MW unit model is developed using the EBSILON software, and the associated energy consumption model is established by passing the simulation results to a MATLAB routine. Then, three distribution methods are used to study the influence of the thermal–electric load distribution on the heat rate. Finally, the energy consumption model is embedded into a momentum particle swarm optimization (MPSO) algorithm, and the thermal–electric load distribution is optimized using the load data from a characteristic day with the operation feasible region taken as the boundary. The results show that the thermal load plays a major role in the energy efficiency of the unit, and the electric load determines the exergy efficiency distribution. The operation mode of the unit has little influence on the energy utilization rate, but has a significant influence on the exergy efficiency. When two CHP units are running in parallel, their heat rate can be reduced by optimizing the thermal–electric load distribution. A more uneven distribution of thermal–electric load between units results in a lower heat rate. The optimized heat rate given by the MPSO algorithm for a characteristic day is 6887.93 kJ·kWh−1, which is 304.44 kJ·kWh−1 less than under the average thermal–electric load distribution. These findings may be helpful to get insight into the energy consumption characteristics of CHP plants and guide for its economic operation. [ABSTRACT FROM AUTHOR]