Research On Monitoring System Of Grid-Connected Distributed Electric Resources Based On WEB Technique

Distributed electric resources(DER)has been an attractive subject recently for its environmental friendly and distributed flexibly,which can make up for the shortcomings of the large power grid mode.With the increasing of the grid-connected capacity,negative effects begin to appear.Present monitoring systems are mainly used in large power stations.High cost,poor flexibility and complexity in installation make them do not apply to the grid-connected DER systems.As a result,exploring a new model of grid-connected DER monitoring system and researching on the key technologies are necessary for developing a new low cost and high flexibility monitoring system to ensure the DER working steadily.On the basis of understanding grid-connected DER systems' characteristics,key technologies,requirement analysis and design principles have been studied and analyzed.After this,a design of grid-connected DER monitoring system based on web has been raised and developed.This monitoring system employs B/S architecture,layered design and modular structure.The key technologies are including web access technology,embedded database technology,metering technology,anti-islanding protection technology and unbalanced power control technology,etc.There are three structural models in the design blueprint: WEB monitoring layer,WEB function layer and physical devices layer.CPU module,I/O module,SQL module are included in the function module block.During the development,CPU,AI,DO and DI in flashboard structure have been used to ensure reliability and compatibility.The software system adopts a hierarchical structure.And the underlying resources can be accessed by applications.The whole monitoring system operates on ?clinux2.6,Boa server,CGIC library and mini SQL.It can meet the need of real-time monitoring and remote access.In the end,the experiment for verification was done in Distributed Power Grid Engineering Research Center.As it turned out the monitoring system can monitoring the grid-connected DER running effectively.The grid-connected DER monitoring system based on web,possessing the functions of remote login,three remotes,anti-islanding protection,unbalanced power control and metering technology etc,can solve the problem of poor flexibility in using the regular systems and monitor the grid-connected DER systems by the client browser in a real time.Compared with the present system,this monitoring system,miniaturized and low cost,can save the expense of constructing monitor,substation and communication networks.It can be remote accessed by WEB flexibly and reliably with operating parameters displaying on the WEB interface.Consequently,this monitoring system can reduce the impact on the grid to keep the DER running reliability,which is benefit to achieve the complementary advantages between grid and DER.The research has guiding function for the DER in large scale connecting with the grid.