Hydraulic disturbance characteristics and power control of pumped storage power plant with fixed and variable speed units under generating mode
Rui Cao, Wencheng Guo, Fangle Qu
Abstract
The variable speed unit (VSU) is one of the future directions of pumped storage power plant (PSPP) technology. The combined operation of fixed speed unit (FSU) and VSU becomes an important operation mode of PSPP and faces the challenge of power control under hydraulic disturbance condition. This paper aims to investigate the hydraulic disturbance characteristics and power control of PSPP with FSU and VSU under generating mode to guide the operation of PSPP. Under the hypothesis of one-dimensional flow, the hydraulic disturbance characteristics and power control are studied by the method of numerical simulation of transient process. Firstly, the mathematical model of PSPP including pipeline system, FSU and VSU is established. Then, based on simulation and contrastive analysis, the hydraulic disturbance characteristics and power control of VSU and FSU are analyzed for two regulation situations and two types of hydraulic disturbance condition. Finally, by determining and comparing the power output and active power of the disturbed VSU and FSU, the effects of location and speed of VSU on the hydraulic disturbance characteristics are revealed for two regulation situations. The results indicate that the hydraulic disturbance characteristics and power control performance of the disturbed FSU and VSU of regulation situation 2, i.e. power mode of FSU and power priority control of VSU, are superior to those of regulation situation 1, i.e. frequency mode of FSU and power priority control of VSU. If the PSPP with different locations of VSU is under regulation situation 2 or the speed of VSU is greater than the critical speed, the power control performance of the disturbed VSU is superior to that of the disturbed FSU. The speed of VSU should not be less than the critical speed to bring the regulation performance of VSU into full play.