Discussion on key issues of primary-secondary-tertiary pumping system design（2）：Operation condition and control mode of tertiary pumps

The tertiary pump of the non-decoupled regional primary-secondary-tertiary pumping system bears the superimposed influence of the head change of regional distribution system and user-side distribution system during operation. Establishes the accessible range of pump’s curve and the demand range of operating condition on the head-flow chart for the tertiary pump, and studies their matching degree. According to the example analysis, puts forward four types of operating areas, and presents the control methods under some conditions. Based on the high efficiency area of pump operation, proposes an optimized operation control strategy.