Research On The Control Strategy Of Stabilizing Wind Power Storage Devices

Energy is one of the important factors restricting the development of world economy.Wind energy,solar energy and tidal energy are increasingly favored by many countries,due to their renewable,pollution-free,green and environment-friendly qualities.For the sake of sustainable development and welfare of the future generation,China attaches increasing importance to the use of renewable energy,and the wind energy is widely developed in the world as new energy.Because of its randomness,intermittency and volatility,wind energy is likely to pose a direct threat to the power network,which restricts the development of the wind power industry.Overcoming the randomness,intermittency and volatility is the key to large-scale development of wind energy.Meanwhile,energy storage technology,which matures day by day,and makes it possible to suppress the fluctuation of wind energy,and outfit the wind power system with a suitable energy storage device may effectively reduce the volatility of wind energy.This thesis focuses on studying the possibility of leveling off the volatility of wind power,as well as the method to prolong the battery life of energy storage system.The main contents are as follows.Firstly,a traditional first-order LPF(low-pass filtering)algorithm is designed to level off the volatility of wind power.The relationship between time length of sampling and SOC max changing range during battery's charging and discharging processes is discussed.And the effect of using filtering constant,TO to level off the volatility of wind power,as well as the relations between TO and the leveling effect,TO's contributions to energy storage is studied.On this basis,a hybrid control strategy is proposed,which is composed of two control methods.It switches in between two control methods in real time according to the magnitude of wind power fluctuation,so as to control the fluctuation of SOC in a reasonable range.It reduces wind power volatility,and it can also ensure sufficient capacity for charge and discharge operation at the next sampling time.Secondly,a first-order cloud model controller is designed.By using the volatility of wind power as the prerequisite and using the cloud model controller to regulate the filtering constant T0 we can realize fast control when there is much volatility of wind power,and at the same time we reduce the contributing requirement for the energy storage device.Thirdly,a 2-dimension cloud model controller is designed.The state of charge and the state of output of battery are used as the regular precursor of the two-dimensional cloud model controller.By detecting the state of charge and state of output of the energy storage battery,the filtering time constant is adjusted in real time so as to improve the suppression effect of the wind power and prevent the battery from circulating charge and discharge.The battery life of energy storage battery may be affected by the single-cycle maximum charging and recharging depth,as well as the switching times of charging and recharging.And therefore,by designing the energy storage device as double-battery packs,we make sure while one battery is charging or discharging,the other is in standby state.The times of charging and recharging of battery pack is reduced and its battery life is prolonged by using two-battery packs storage.