Research On Optimal Economic Control Strategy Of DC Microgrid Based On Stability

Energy is the basic element of nature society,also is the important material basis in national economy.With the development of society,the energy demand become larger.The traditional fossil energy largely used at this stage would be exhausted at 2050.At the same time,with the world environment and climate question worse and worse,an energy revolution that the traditional fossil would be replaced by renewable energy is spread out.Renewable energy is regarded as primary energy,so it can be used by people only when it is translated to secondhand energy.For example,renewable energy distributed generation technology translates the sun,wind,tide energy and other renewable energy to electric energy.The electric energy can be transmitted to utility grid for human using.In order to decrease the energy loss and make the electric energy consume locally,the micro grid technology appeared.Compared to AC micro grid,DC micro grid which has the advantage of less energy conversion,easier control and small system energy loss has a brighter development future and research space.This paper firstly analysis the mathematic model and compound mode of photovoltaic.Establishing the Matlab/Simulink simulation after simplify the photoelectric characteristic equation.Paying more attention to photovoltaic maximum power point tracing and constant voltagecontrol mode.And proposing the mixed variable step size tracing algorithm based on original MPPT algorithm.According to circuit design and parameter selection,making the simulation experiment based on temperature and sun changing.The result proved that the proposed method is more superior to the original one.Then,proposing a method of parallel structure hybrid energy storage current sharing and control strategy based on the mathematic model and operating principle of lithium battery and super capacitor.Taking advantage of proposed DC/DC conversion circuit to prove the method above mentioned.The consequence proved that the mentioned control method can combine the advantage of lithium battery and super capacitor,enhancing the lifetime of hybrid energy storage and control flexible.In this way,the DC bus of DC micro grid can be stabilized sooner.Next,based on float electric price in Shenzhen,proposing a DC micro grid topology which consists of electric vehicle.Analyzing the DC micro grid stability on island and grid connected mode based on economy principle.Finally,setting up the DC micro grid model which is combined PV,Hybrid Energy Storage System,load and EV.Verifying the proposed whole control strategy and to prove the attitude correction and effectiveness.