The monitoring of power system events on transmission and distribution level by the use of phasor measurement units (PMU)

Abstract

Large power system disturbances and their consequences, represent a challenging problem for the power industry and especially for the network system operators, the ones who are responsible for the network operation at large, its security and reliability. This fact has reinforced interest in the new generation of monitoring systems with the aim to gain if possible a precise and maximum knowledge about those disturbances and their impact. Most of these severe events with impact on the entire system typically occur in or near the transmission network and are therefore best monitored at transmission system level. This puts great demands on the equipments and in general restricts the use of the data since it becomes property of the transmission system operator. Synchronized Phasor Measurement System has emerged as a powerful tool to improve power systems performance and reliability and fault localization possibility. Typical example of fault event that occurred in the transmission system and which was well registered by Phasor Measurement Units

Synchronous phasors monitoring system application possibilities

“…A combination of unusual events (line disconnections due to short circuits together with the decision of the dispatching centre to trip one line because of overload) triggered other cascading disturbances. [3] It is assumed that this was related to the oscillation phenomenon which was registered at this moment. Because of these outages the Czech system broke into two islanding operations.…”

The phase sequence selection for cables lines at Extra High Voltage level

“…This solution is more expensive than construction of overhead lines and brings new issues to planning and operation of power systems as well, the operation issues can be partly solved by new monitoring systems [2]. However, in some cases it may be the only suitable solution.…”

State estimation of Active Distribution Networks: Comparison between WLS and iterated kalman-filter algorithm integrating PMUs

“…In the last decade, the large use of the so-called Phasor Measurement Units (PMUs) for the monitoring of the transmission networks, has influenced the operational practices of these systems concerning the following aspects: i) system stability; ii) state estimation (SE); iii) system reliability; and iv) protections schemes (e.g. [3]- [9]). In view of the evolution of distribution networks from passive S. Sarri, R. Cherkaoui and M. Paolone are with the École Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland, (e-mail: styliani.sarri@epfl.ch, mario.paolone@epfl.ch, rachid.cherkaoui@epfl.ch).…”

“…However, in KF-based SE methods this equation is only used to provide the so-called a-priori estimation of the system state at a given time step. In principle, the proximity of the a-priori state predicted by (9) to the real one has a direct influence on the number of iterations that the KF has to perform to converge. As this aspect deserves specific investigations, we are here assuming for the a-priori estimated state the so-called 'flat-start' composed by voltage angles are equal to zero and voltage magnitudes equal to one in per-unit: ( )…”