| Vigorously developing distributed renewable energy is an urgent need to achieve sustainable development.However,the intermittence and unpredictability of distributed renewable energy seriously affect the security and reliability of power system,so the utilization of distributed renewable energy is very low.The basic reasons are as follows: firstly,the existing concept of power transmission and distribution is that the power generation follows the demand of the user,that is,the balance of power transmission and distribution can only be controlled by the power generation terminal,which makes the degree of control freedom very low.Secondly,most of the existing distributed power grids are large-scale and large-capacity.The intermittent of these grids brings many problems such as large power fluctuation and harmonic pollution,which cannot be solved locally by means of absorption.Thirdly,the traditional control strategy mainly achieves the power balance of the grid by cutting off the distributed renewable energy,which leads to low efficiency of power conversion.In view of the above problems,this paper proposes a microgrid architecture and control strategy that can realize the high proportion of distributed renewable energy utilization based on the concept of demand side response.The main research contents are as follows:1)Aiming at the low utilization of distributed renewable energy grid connection,a novel structure of microgrid is proposed,which realizes the high utilization of distributed renewable energy grid connection.The idea of "turning whole into zero" is applied to the grid connection of distributed renewable energy and some electrical equipment is used as the energy elastic storage device on the demand side.This architecture can not only avoid the loss caused by multi-level energy conversion,but also use the energy elastic storage device to follow the fluctuation of distributed renewable energy generation,and ensure the safe and stable operation of the power grid under the high permeability of distributed renewable energy.2)Aiming at the problem of low efficiency of power conversion,the corresponding high-efficiency power conversion control strategy is designed.On the premise of high utilization,the designed microgrid presents pure resistance and piecewise constant active power features to the upper power grid,so that the fluctuation of distributed renewable energy can be eliminated at the demand side,and the performance index of controllable power consumption and zero pollution can be achieved.The control strategy is divided into a system-level control strategy and a converter-level control strategy.The systemlevel control strategy aims to minimize the power loss of electronic devices and the life loss of the energy storage equipment.Then particle swarm optimization used to achieve optimal control,which are taken high utilization of distributed renewable energy,pure resistance and piecewise constant active power features as conditions.The converter-level control strategy is based on the optimal solution obtained by the optimization algorithm,and the vector control strategy and the corresponding modulation method controls the converters to achieve the corresponding control objectives.The innovations of this paper are as follows:(1)A distributed renewable energy microgrid architecture that considers household flexible storage devices is proposed to increase the utilization from the demand side.(2)Piecewise constant active power feature is presents to grid,which can consumptive the fluctuating power locally and reduce the difficulty of dispatching the upper-level power grid.(3)Presents pure resistance is presents to grid,which can eliminate harmonic pollution and achieving zero pollution to the upperlevel power grid. |
