火电厂给水系统功频约束对电力系统频率特性的影响

精细的系统频率响应模型是准确分析电力系统频率特性的基础,现有的频率响应模型未考虑大频率偏移下火电厂给水系统功频特性及其约束对系统频率特性的影响,难以准确分析严重频率偏移下的电力系统频率特性。给水系统出力变化影响机组出力,对机组的安全稳定运行起着重要作用。首先,分析了给水系统的功频特性;然后,建立了考虑给水系统的频率响应扩展模型,在更大频率偏移范围内分析了给水系统功频约束对机组静态功频特性的影响,发现机组出力随频率降低先增加后减小;最后,基于PSS/E开发了扩展频率动态仿真分析工具,并通过39节点算例分析了不同扰动下给水系统功频约束对电力系统静态功频特性和频率响应特性的影响。

Impact of Power-Frequency Constraint of Feedwater System in Thermal Power Plant on Frequency Characteristics of Power System

A detailed system frequency response model is the basis for accurately analyzing frequency characteristics of the power system. The existing frequency response models do not consider the impacts of the power-frequency characteristics of the feedwater system in the thermal power plant and its power-frequency constraints on the system frequency characteristics under large frequency deviation. It is difficult to accurately analyze power system frequency characteristics under severe frequency deviations. The output change of the feedwater system affects the output of the unit, which plays an important role in the safe and stable operation of the unit. Firstly, the power-frequency characteristics of the feedwater system are analyzed. Then an extended frequency response model considering the feedwater system is constructed. The impacts of the power frequency constraints of the feedwater system on the static power-frequency characteristics of generating units are analyzed within the larger frequency deviation range and it is found that the generator output increases first and then decreases with frequency declining. Finally, the extended frequency dynamic simulation and analysis tool is developed based on the PSS/E. The impacts of power-frequency constraints of the feedwater system on the power system static power-frequency characteristics and frequency response characteristics are analyzed under different disturbances in the 39-bus system.