Fine Modeling And Optimization Control Research On The Governing System Of Pumped Storage Unit

Pumped-storage power station, which has become the major economic and realistic means to regulate peak and valley load and guarantee the reliable operation of the power system, plays the significant roles of load scheduling, energy-saving promotion and system security and stability maintenance in modern power grids for its characteristics of emergency standby, fast load tracking and frequency-phase modulation. Compared with conventional hydroelectric generating units, pumped storage units have shown the privilege in working in complicated situations with greater head variation, frequently condition conversion and bidirectional flow, which makes the turbine governing system a complex non-minimum phase and hydro-mechanical-electrical coupled nonlinear systems with great difficulty in modeling and control optimization.For the sake of precisely modeling the complex structure of water diversion system composed of elastic pipeline, surge tank, valve and pump turbine, the equivalent circuit model simulation, which naturally transforms hydraulic analysis to circuit analysis and is capable of tackling variable spatial scale dynamic simulation of the hydraulic pipeline with high accuracy, has been introduced in this paper. Taking the interpolation problem in pump turbine characteristic curves into consideration, the improved Suter transformation is utilized to avoid the phenomenon of cross and aggregation of the opening line for its high interpolation precision and a more general algorithm for water-head calculation is proposed to solve the limitation of waterh-head solution in improved Suter transformation. On the basis of studying on modeling mechanism and simulation algorithm, a precise mathematical model for governing system of pumped storage unit including pressure water system, pump-turbine, generator-motor and pump turbine governor is established. Furthermore, a linear small signal model for pumped storage turbine governing system especially for the analysis of the dynamic response of small disturbances at nominal operating point has also been proposed to simplify the model of the water diversion system. Experiments have been conducted to validate the superiority of the small signal model.In order to improve control performances in the governing system of pumped storage unit and realize control optimization under the unit's operation condition, simulation research has been carried out on the condition conversions of the governing system of pumped storage unit and regulating process in the governing system has been analyzed. Moreover, control parameters sensitivity under small disturbance in primary frequency regulation has also been extensively studied and intelligent algorithms are introduced to optimize the PID control parameters. Finally, the wicket linear closure law and the integrated closure law of guide vane and ball valve to optimal control during load rejecting conditions have been analyzed in this paper.