Measurement And Analysis Of Power Quality In Wide Area Network

Power quality measurement is an important issue to ensure the stability and economy of power system. By power quality measurement (especially on-line measurement), status of power network can be obtained, and forepart failtrue signals are captured to indicate a necessary mitigation step. This issue is significant for both electricity supplier and customer since advanced measurement technology can increase the security and reliability of power system and ensure the economical and continuous operation of electrical facilities.For power quality measurement and analysis in wide area network, this work carries out four programs shown as follows:First, the state of art measurement approaches in both Chinese domestic and international power quality research filed are summarized. The measurement indices, standards and analytical methods are discussed. We make prominent efforts for harmonics analysis and introduce several traditional algorithm and novel algorithms.Second, the technology of establishing a power quality measurement system in wide area network (Ethernet) using PowerSATALITE II is presented in detail. Its communication technology and real time technology are discussed. In this measurement system, cable Ethernet is utilized to construct the network, and server-client mode is adopted. This system is equipped with 32 bit float processor and 16 bit A/D converter which provide high processing accuracy. An extended Globe Position System (GPS) module provides the function of simultaneous triggering among several measurement terminals in wide area network. The trigger time error is restricted within 10us which is beyond the accuracy of similar instruments at home.Then basic function module of central software is introduced. We improve the harmonic analysis module using MATLAB language. MATLAB is utilized here to write FFT algorithm. The MATLAB program is translated to a MS Excel package which can run without MATLAB environment using Excel Builder function. The package is subsequently macro-complied in Excel to realize the harmonic analysis based on FFT algorithm using MATLAB language.Finally, a great deal of testing experiments is carried out to verify the feasibility and stability of proposed power quality measurement system. The system was installed in a residential district where original data were collected for a whole day. The harmonic graph along time scale can be extracted from raw data using software aforementioned which intuitively presents the harmonic level in this district.