Nonlinear Modeling and Stability of a Doubly-Fed Variable Speed Pumped Storage Power Station with Surge Tank Considering Nonlinear Pump Turbine Characteristics

Abstract

This paper investigates the nonlinear modeling and stability of a doubly-fed variable speed pumped storage power station (DFVSPSPS). Firstly, the mathematical model of DFVSPSPS with surge tank considering nonlinear pump turbine characteristics was derived and established. Then, Hopf bifurcation analysis of DFVSPSPS was performed. The stable region was identified and verified by example analysis. Moreover, the effect mechanism of nonlinear pump turbine characteristics on the stability of DFVSPSPS was explored. Finally, the influence of factors on the stability and dynamic response of DFVSPSPS was studied. The results indicate that the emerged Hopf bifurcation of DFVSPSPS is supercritical and the region on the low side of the bifurcation line is the stable region. Nonlinear head characteristics have a significant influence on the stability and dynamic response of DFVSPSPS. Nonlinear speed characteristics have an obvious effect on the stability and dynamic response of DFVSPSPS only under positive load disturbance and unstable surge tank. Nonlinear head characteristics are unfavorable for the stability of DFVSPSPS under positive load disturbance and favorable under negative load disturbance. A smaller flow inertia of penstock, a smaller head loss of penstock and a greater unit inertia time constant are favorable for the stability of DFVSPSPS. The stable region under the positive disturbance of active power is larger than that under the negative disturbance of active power. The time constant of the surge tank presents a saturation characteristic on the stability of DFVSPSPS.

Study on Influence of Flow Inertia of Pressure Pipe on Critical Stable Sectional Area of Surge Tank

“…The basic equations of the diversion system including the surge tank are the flow continuity equation in the surge tank, the equation of motion, and the equation of flow motion in the pressure pipe [4][5][6][7] : T  is the coefficient of head loss in pressure channel; P  is the coefficient of head loss in pressure pipe.…”

Preliminary study on power regulation rapidity in pump mode of variable-speed pumped storage unit with DFIM

“…Giovanna Cavazzini et al [10] illustrated the effect of the S-Shape zone in turbine mode and the hump zone in pump mode on power regulation. Nan Zhang et al [11] explored the effects of various factors on the stability and dynamic response rate of a VSPSU.…”

Quantifying power regulation characteristics in pump mode of variable‐speed pumped storage unit with DFIM

“…Cavazzini et al 34 illustrated the influence of the S‐shape zone and the hump zone on the power regulation of VSPSU and proposed that not only both pump mode and turbine mode should be considered at the same time when optimizing the stability of the pump–turbine. Zhang et al 35 established a model of VSPSU with a surge tank and explored the effects of various factors on its stability and dynamic power response. Guo and Zhu 36 described variable‐speed PSP (VSPSP) as a fifth‐order nonlinear system and analyzed its operational stability through mathematical methods.…”