| The centralized wind power resources have been developed and utilized on a large scale,and the distributed wind power resources still have a considerable stock.The integration of the distributed wind power into the micro grid has become an effective way to improve the renewable energy penetration at the end of the grid.Distributed wind turbine load shedding control technology,large-scale energy storage technology and grid operation control technology will become an important development direction of energy technology.The research on the optimal control of micro grid with distributed wind power generation needs to be carried out from two aspects:the single machine of distributed wind turbine and the optimal control of micro grid.Supported by the National 863 program smart grid key technology research and development project "research and development of wind farm and photovoltaic power plant cluster control system”(2011aa05al 04),the research work and achievements are as follows:1.Optimal load reduction control of distributed wind turbineThe theory of model predictive control(MPC)is studied and the model predictive control model is established.Considering that the operating point of the wind turbine is always changing with the wind speed fluctuation,the load reduction control effect of the single point model predictive controller will be affected,and the stability of the output of the distributed wind turbine needs to be enhanced.Based on the analysis of the operation characteristics of wind turbine in the whole wind speed range,a multi control target based wind turbine operation range division method is proposed.According to the measured wind speed and the estimated wind speed based on the state of the unit,the operation range of the unit is divided into five wind speed ranges.In order to ensure that the five MPC controllers based on the multi-objective division method can output control signals continuously at each working point,a multi model predictive control(multi MPC)model is established.A joint real-time simulation platform based on MATLAB and TUV GL bladed is established.After comparing and verifying the advantages of MPC controller with traditional PI controller,taking the nonlinear model of 2MW doubly fed wind turbine in GL bladed software as the research object,the multi MPC controller,MPC controller and traditional PI controller are simulated and compared.The simulation results show that the multi MPC controller can reduce the speed fluctuation amplitude of the wind turbine,restrain the speed overshoot,reduce the load of the transmission chain,restrain the fluctuation amplitude and change rate of the pitch angle,and reduce the operation load of the pitch mechanism.2.Microgrid operation optimization based on demand side responseIn order to achieve the maximum local consumption of the distributed wind power generation output,based on the demand side response mechanism,load reduction constraints,load reduction climbing constraints and total load reduction constraints are established,and the objective function is to maximize the net load demand of the microgrid system.The cost model of wind turbine and energy storage system considering charge discharge times and charge discharge depth are established.Based on the established cost model of wind turbine and energy storage system,the objective function with the minimum operating cost of micro grid system as the objective is set,which takes power balance constraint,power transmission constraint between systems and energy storage system operation constraint as the boundary conditions,considering demand side response mechanism and power purchase and sale cost.Based on the improved differential evolution algorithm,the objective function is optimized and compared with the solution based on genetic algorithm.The results show that the improved differential evolution algorithm can improve the economic efficiency and the life of energy storage system.Based on the improved differential evolution algorithm,three kinds of boundary conditions based on demand side response and energy storage system are compared and analyzed.The research results show that good demand side response mechanism and healthy charging and discharging of energy storage system are the key to the optimal operation of microgrid.The microgrid optimal scheduling model based on demand side response,energy storage life and electricity price factors optimizes the life of energy storage system,improves the life of energy storage system and the economy of microgrid.3.Regional optimization of composite energy storage in microgridThis paper reveals the structural characteristics and load time distribution of microgrid,and introduces the composite energy storage technology and the type selection of composite energy storage system.Based on the comprehensive energy system resources and load characteristics,geographical conditions,fixed assets coverage area,the micro grid area division method is proposed.Based on the power balance constraints,power transmission constraints between micro grid and external grid,operation constraints of lithium iron phosphate battery and super capacitor,capacity constraints,the annual cost function of energy storage system is established.Finally,the boundary conditions of composite energy storage system operation,power balance and grid connected transmission are established,and the maximum annual revenue of microgrid system is taken as the objective function of economic optimization criterion.The improved particle swarm optimization algorithm is used to solve the problem.The research results show that the proposed regional optimization method of wind/photovoltaic/microgrid composite energy storage system and the adaptive regional stratification of microgrid are proposed The control strategy can effectively suppress the fluctuation of power side and user behavior in microgrid system,improve the power grid's ability to absorb renewable energy,and reduce the impact of renewable energy on the external power grid.4?Optimal scheduling of integrated energy system considering the stochastic model of prediction errorThe structure and load change characteristics of integrated energy system are studied.Based on the wind power,photovoltaic power generation output and load fluctuation,the prediction error stochastic model is established.The objective function of the minimum comprehensive operation cost based on the operation cost of wind power,photovoltaic power generation,diesel power generation and energy storage system and the cost of purchase and sale of electricity is established.The boundary conditions are power balance constraint,power transmission constraint between systems,energy storage system operation constraint and diesel generator operation constraint.Under the given real-time electricity price condition,wind power/photovoltaic/load curve,improved particles are adopted Group algorithm.The research results show that the optimization of energy storage system and diesel power generation scheduling model,the optimization of energy storage system operation scheduling and diesel generator output can make up the difference between the actual value and the pre-determined value of power generation or consumption under the optimal economic operation condition,and the micro grid system can not only better suppress the fluctuation of wind and solar load,but also better control the fluctuation of wind and solar load It can realize the optimal economic operation.Therefore,it is necessary to arrange the type and quantity of distributed power reasonably according to the actual situation and the demand of regional scheduling of integrated energy system. |
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