Design And Control Strategy Research Of Non-grid Wind Power Direct Supply System

In geological engineering such as sea water desalinization and oil production, water raiser, high pressure pump and oil sucking machine, etc. consume large amount electric power, which is the main bottleneck of energy conservation and emission reduction for these engineering. Renewable energy such as wind power and solar energy is a new solution for geological engineering power supply, which is clean, highly efficient and green.Because the stability problem brought by grid-connected wind power has not been solved fundamentally yet, micro-grid theory and non-grid-connected wind power theory have been put forward, which cut off the connection of wind power and grid. Combined with large consumer direct supply theory for power market, this paper proposed the non-grid-connected wind power direct supply (NWPDS) theory. The core is wind power is directly send to the heavy loads such as sea water desalinization and oil production, without grid transformation. The main content and research achievement are as follows:I. Proposed the whole design solution of NWPDS system.The NWPDS system is composed of wind farm, hybrid DC transformation, energy saving device and grouped load controlled by solid switch, whose design and operation target is to ensure supply reliability and maximum utilization of wind power. The hybrid DC transformation system combined the low cost of current source converter (CSV), the voltage control ability and supply ability to passive load of voltage source converter (VSC). Energy saving device is attained by parrelled super capacitor and battery. The relationship between energy saving device and wind power utilization is studied and the optimization necessity of energy saving device capacity and power rating is pointed out. The genetic algorithm based on oriented evolution is proposed to optimize the energy saving device parameters. The simulation results verified its correctness.II. Proposed the control strategy of NWPDS system.Compared with micro-grid and grid control, the opinion that the main control objects in NWPDS system are energy saving device and load is proposed. Based on this opinion, the control strategy of the active power and reactive power decoupled in physical is proposed. The reactive power control is realized by VSC, and the active power control is realized by energy saving device and load control. In active power control, three-level frequency control is proposed, including prediction control based on wind power prediction and pre-set load curve, energy saving control for rapid wind power fluctuation and load control. Simulation verified the validity of the control strategy.III. Power quality of non-grid-connected wind power is analyzed also. Aiming transient power quality disturbance classification problem, the method combined wavelet transformation and fuzzy logic was proposed. Simulation result identified that this intuitive method is of high accuracy, which is basic for solving NWPDS power quality problem.IV. A lab system of NWPDS sea water desalinization was introduced. The running results verified the correctness and validity of the theory proposed in this paper.