Research On Reactive Power Optimal Control For CSP-PV Hybrid Power Generation System

Solar energy has the highest storage capacity among many clean and renewable energy sources,and is basically pollution-free.Solar power generation technology has huge development potential and broad application prospects.At present,domestic solar power generation technology is divided into two major technical fields: concentrated solar power(CSP)generation and photovoltaic(PV)power generation.CSP is an emerging form of solar power,the coordinated operation of CSP and large-scale photovoltaic power generation and AC-DC hybrid power grids can absorb intermittent and random renewable energy,thereby realizing renewable energy consumption and renewable energy.Therefore,it is of great significance to build a source-side energy power system mainly based on PV and CSP.However,reactive power control of CSP-PV hybrid power system is based on independent control of CSP and PV power stations,in other words,independent control by a single power station will not guarantee the voltage regulation requirements of the global system.So,this thesis will start the research on the reactive power optimization control strategy of CSP-PV system,the specific research work is as follows:(1)Based on the CSP generation technology and PV power generation technology,this thesis establishes the mathematical models of CSP and PV power generation respectively,and analyzes the optimized operation mode and characteristics of reactive power output of the CSP-PV hybrid power generation system.(2)This thesis proposes a dynamic reactive power planning method suitable for CSP-PV hybrid power generation system.The method determines the installation node of the dynamic reactive power compensation device and its compensation capacity based on the system's own reactive power adjustment capability.The critical fault node is determined by the transient voltage stability recovery index,and the weak node of the system is initially determined.And based on this,the sensitivity index is used to determine the installation node of the dynamic reactive power compensation device.Dynamic reactive power planning optimization model is established with the lowest investment cost of dynamic reactive power compensation device and the improvement of system transient voltage stability.And besides,the component of the reactive power compensation node is optimized by Particle Swarm Optimization Based on Differential Evolution.The simulation results of the example system show that compared with the dynamic position compensation device installation location optimization method,the proposed method can improve the transient voltage stability of the system under the same reactive power compensation cost.(3)From the perspective of multi-level,a coordinated optimal control strategy of reactive power based on hierarchical control theory on CSP-PV hybrid system is proposed,which contains three parts.First,the system reference values of reactive power were estimated.Second,the optimal reference values of reactive power for each power station at each PCC were calculated.Third,reactive power distribution of equipment in the station were estimated.The simulation results show the control strategy fully utilizes the reactive power control capability of the synchronous generator,the photovoltaic inverter and the reactive power compensation device,which realizing the optimal distribution of the reactive power compensation task in the CSP-PV hybrid system,and improving the system integration bus voltage stability and reducing the network loss.(4)From the perspective of multi-time scale,a multi-time scale reactive power optimal control strategy based on the theory of MPC on CSP-PV hybrid system is proposed.Based on the day-ahead optimal reactive power of synchronous generator and photovoltaic inverter,the bus voltage is controlled by dynamic reactive power compensation equipment within the intra-day time scale,which adopts the idea of rolling optimization and correcting control based on MPC.The voltage prediction model based on sensitivity is used to predict the voltage states at multiple moments in the future;On the basis of that,the intra-day rolling optimization model is established with the minimum deviation of the predicted voltage control at multiple future moments as the optimization objective to obtain the reactive power control plan of the dynamic reactive power compensation equipment,and the model predictive control of the in-day-reactive power and voltage is completed by feedback correction of the voltage control deviation.The simulation results show that by comparing with the traditional multi-time scale reactive power optimization control strategy,the proposed control strategy in improving the stability of system bus voltage and the PCC bus voltage for concentrating solar power station and photovoltaic power station are better.