Abstract:

The complex gas engine-driven heat pump (GEHP) is composed of a gas engine, a heat pump as well as a data acquisition and control sub-system. Effective control of the gas engine speed and evaporator superheat is necessary for safe and highly efficient operation of a GEHP. Based on the characteristics of the gas engine and the heat pump, a simultaneous control strategy was developed with an expert PI controller for engine speed and gain-regulating controller for evaporator superheat. Simultaneous control studies were performed on a GEHP system over a wide range of engine speed and evaporator superheat. When the set point of evaporator superheat was changed, superheat overshoot was less than 1℃ and the engine speed control showed strong anti-interference. When the set point of engine speed was changed, the engine speed control showed a good performance with no overshoot and the superheat fluctuated within a range of less than 0.5℃. The experimental results also show that the simultaneous controller run well in terms of settling time and overshoot when the set points of engine speed and superheat were changed continuously. The research findings will provide technical support for design of automated GEHP control system.

Key words: natural gas, thermodynamics, compressor, gas engine-driven heat pump, gas engine speed control, superheat control, simultaneous control

摘要：

燃气机热泵是由燃气机、热泵系统和数据采集控制系统组成的复杂系统。系统运行过程中，燃气机转速与蒸发器过热度的有效控制是系统安全高效运行的前提。根据燃气机及热泵系统的特性，设计了燃气机转速与蒸发器过热度联合控制策略，其中燃气机转速采用PI控制，蒸发器过热度采用增益调度控制，并将该控制策略应用于燃气机热泵的控制，对燃气机转速与蒸发器过热度的联合控制进行了试验。当蒸发器过热度设定值改变时，过热度的超调量小于1℃，转速控制表现出较强的抗干扰性能；当燃气机转速设定值改变时，燃气机转速基本没有出现超调，过热度的波动范围小于0.5℃。试验结果表明，当燃气机转速设定值和蒸发器过热度设定值连续改变时，联合控制策略同样表现出良好的动态响应特性和抗干扰性能。本文结果可以为燃气热泵的自动控制系统设计提供技术支持。

关键词: 天然气, 热力学, 压缩机, 燃气机热泵, 燃气机转速控制, 过热度控制, 联合控制