AN INTEGRATEDPMU AND PROTECTION SCHEMEFOR POWER SYSTEMS

synchronised with a GPS-clock and compute the corresponding phasor component from widely dispersed locations. Phasor technology provides time synchronized sub­ second data, which is applicable for wide area monitoring; real time dynamics and stability monitoring; and improvements in state estimation, wide area protection and controls. The implementation in WAMS technology thus far, however, is designed as an independent measurement unit, the PMU (Phasor Measurement Unit). The PMU device, although it may be implemented as a substation lED and even merged into an individual protective relay, usually its functions are separated from local protective systems. By this arrangement, it is difficult to coordinate the system monitoring, control and backup protection with the local protection systems, which could result in a conflict of interests between the system control and local protection and prevents correct actions being taken in case of system emergency. At the same time, with more and more substation IEDs (Intelligent Electronic Devices) being put into operation, increased complexity results from a number of issues, such as commissioning, maintenance and EMC (Electro Magnetic Compatibility). This paper presents the design and development of a novel scheme for the integrated control and protection of power transmission systems. The scheme integrates local and wide area control and protection systems by implementing the WAMS function and substation protections into one system. This integrated system coordinates stability and emergency control, system oscillation detection and protection.