Secondary Control Of Microgrids Based On Multi-agent System

In recent decades,the energy crisis and environmental pollution problems are getting worse.In order to alleviate the energy crisis and environmental pollution problems,domestic and foreign scholars put forward to distributed generation technology which use renewable energy as the main power generation form.However,a large number of distributed generator connect with main grid has brought a lot of adverse consequences.In order to reduce the impact of distributed generator on the power grid,micro-grid was put out.The output voltage amplitude and output frequency of the distributed generator are important indicators to measure the quality of the generator.Only by stabilizing the generator in the vicinity of the rated value can the power system be safe and reliable operation.In the connect network operation mode,the voltage amplitude and frequency of the microgrid system are provided by the main power grid.Once the island operation mode is entered,the output voltage amplitude and output frequency of the system fluctuate violently.In order to stabilize the amplitude and frequency of the voltage,the researchers took the droop control strategy,also known as the primary control;however,the steady-state voltage and frequency under the primary control were all lower than their own ratings.In order to make the system output voltage amplitude and output frequency are restored to their respective ratings,with the introduction of secondary control.The traditional microgrid secondary control adopts the centralized control structure of the central controller,but this structure has many defects,which makes the system reliability and scalability worse.Such as complex communication network,large traffic,and do not have "plug and play" function.In view of the above problems,this paper presents a distributed coordinated control strategy,the following aspects of the study:?The distributed control structure of microgrid is studied.The structure consists of three modules: the primary control module based on the droop control,the distributed secondary coordination control module and the distributed economic dispatching module.The structure simplifies the communication network of the system,reduces the communication traffic,the distributed generator can be plug and play,the reliability and expansibility of the microgrid system has been improved.?Based on t he coordinated control theory of multi-agent system,a distributed coordinated control strategy is designed for the secondary control problem of microgrid.The controller in this strategy only needs the signal of each distributed generator itself and the distributed generator signal which communicates directly with it,can realize the output voltage amplitude and output frequency recovery control of DG.At the same time,the distributed generator output active power and output reactive power in proportion.?Design a distributed second-order coordinated control strategy with finite time.By introducing the segmentation function,the output voltage amplitude and output frequency of the distributed generator in the system are restored to their respective rated values in finite time,and achieve output active power and output reactive power of distributed generator proportional distribution in finite time.