Research Of Smart Grid Wide-area Measurement Cyber-Physical System

Wide-area measurement system (WAMS) which is based on synchronous phasor measurement unit (PMU) and an important development direction of smart grid can realize dynamic monitoring in power grid and make sure safe and stable operation of power grid. High frequency data acquisition in WAMS especially a sharp rise in the amount of data when the power grid in emergency will lead to huge amount of data transmission which is easy to cause network overload and increase network time delay. These problems will seriously affect real-time requirements of dynamic monitoring in power grid.Cyber physical system (CPS) seamlessly integrate computation, communication and control. This proposed the CPS technology could be applied in WAMS in order to solve the huge amounts of data transmission problem. This dissertation has completed the following research work:(1) Based on in-depth investigation of WAMS architecture and research of the key technology of CPS, Smart Grid Wide-area Measurement Cyber-physical System (SGWAMCPS) is proposed to solve the problem of huge amount of data transmission in WAMS. The architecture of SGWAMCPS is constructed based on the concept of CPS technology, which has four layers including PMU data-fusion physical layer, high-speed network layer, middleware-service layer and smart grid senior application layer. The definition and function of each layer are introduced in detail.(2) In orde to decrease data transmission quantity, senior application specified data fusion method which is carried out in the PMU data-fusion physical layer of SGWAMCPS is proposed. Compared with various data fusion technologies, Five categories in-network data fusion algorithm is proposed to effectively reduce the amount of PMU data transmission. Then taking voltage stability monitoring application which is the typical senior application in WAMS as an example, this dissertation has proposed a voltage stability index (VSI) which is suitable for SGWAMCPS, and has designed the data fusion algorithms which can be used for the voltage stability monitoring application.(3) The publish-subscribe middleware is applied in the middleware-service layer of SGWAMCPS. For the implementation of the middleware, this dissertation has proposed a three-layer network architecture, which is built upon IP network model. The publish-subscribe middleware could open an application-specified programming interface, which adopts the corresponding declarative publish-subscribe data model, and allows smart grid senior applications to subscribe to the published PMU data streams, and meanwhile specifies additional data fusion function.(4) Based on IEEE300 test system, a typical power system simulation model is designed and implemented to prove the proposed in-network data fusion algorithms used for the voltage stability monitoring senior application. The simulation result shows that the proposed four kinds of algorithms are applicable to reduce 40%-50% data transmission amount without affecting the accuracy of voltage stability index (VSI), which will effectively reduce the cost of information, and improve the efficiency of network transmission.This dissertation has improved the traditional architecture of WAMS based on the concept of CPS technology and proposed the in-network application specified data fusion to reduce network data transmission. The effectiveness of the proposed method is validated by simulation. The future research direction can be carried out in comprehensive sensors data analysis and data stream processing technology.