The aim of this paper is to assess the capability of the emerging synchronized phasor measurement technology in improving the overall stability of the Hydro-Quebec transmission system through supplementary modulation of voltage regulators. Following a thorough singular value and eigenvalue analysis of the system dynamic interactions, five control sites consisting of four generators and one synchronous condenser are chosen to implement new power system stabilizers with a supplementary input from remote phasor measuring units, geographically spread over nine electrically coherent areas. Since the remote feedback loops are built on top of an existing decentralized control system, this design approach results in a decentralized/hierarchical control architecture with significant advantages in terms of reliability and operational flexibility. A systematic control and measurement pairing yielded four dominant natural loops, each associated with a significant open-loop inter-area oscillatory mode at 0.06, 0.4, 0.7 and 0.95 Hz respectively. These PSSs have a speed sensitive local loop operating in the usual way, and a wide-area measurement based global loop which involves a single differential frequency signal between two suitably selected areas. The tuning and coordination technique for these advanced multiple input signals PSSs is described. Their impacts on the system is assessed using both small-signal analysis and nonlinear simulations in a transient stability program. Wide-area stabilizing controllers have a significant potential in improving the dynamic performance of the Hydro-Quebec's existing power system.

Wide-area measurement based stabilizing control of large power systems-a decentralized/hierarchical approach

This paper presents a critical review on different application of Phasor Measurement Units (PMUs) in electric power system
networks incorporated with FACTS controllers for advanced power system monitoring, protection, and control. Also this paper
presents the current status of the research and developments in the field of the applications of PMUs in electric power system
networks incorporated with FACTS controllers. Authors strongly believe that this survey article will be very much useful to the
researchers for finding out the relevant references in the field of the applications of PMUs in electric power system networks
incorporated with FACTS controllers.

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Applications of phasor measurement units (PMUs) in electric power system networks incorporated with FACTS controllers

Over roughly the past two decades, an architecture has evolved for using wide area measurement systems to monitor power-system oscillatory dynamics. This includes, but is not limited to, the use of phasor measurement units and advanced signal processing algorithms. Today, this architecture is further evolving toward real-time operation applications. This paper provides a perspective upon these analysis approaches, and defines and clarifies analysis operations, interactions, and application conditions. An overview of WAMS analysis approaches is given along with several examples from the western North American power system.

A Perspective on WAMS Analysis Tools for Tracking of Oscillatory Dynamics

This paper presents a method to detect dynamic events in electric power networks by analyzing the frequency signals with Haar wavelet. The estimated post-event damping is used to determine the end of these events, and to separate overlapping events. This method has been implemented and tested on archived field data with good results. It can potentially be implemented in phasor measurement units for dynamic event recording and wide area stability control.

Dynamic event detection using wavelet analysis

Recent large-scale blackouts revealed that power systems around the world are far from the stability and reliability requirement as they suppose to be. The post-event analysis clarifies that one major reason of the interconnection blackout is lack of wide area information. Frequency dynamics is one of the most important parameters of an electrical power system. In order to understand power system dynamics effectively, accurately measured wide-area frequency is needed. The idea of building an Internet based real-time GPS synchronized wide area Frequency Monitoring Network (FNET) was proposed to provide the imperative dynamic information for the large-scale power grids and the implementation of FNET has made the synchronized observations of the entire US power network possible for the first time. The FNET system consists of Frequency Disturbance Recorders (FDR), which work as the sensor devices to measure the real-time frequency at 110V single-phase power outlets, and an Information Management System (IMS) to work as a central server to process the frequency data. The device comparison between FDR and commercial PMU (Phasor Measurement Unit) demonstrate the advantage of FNET. The web visualization tools make the frequency data available for the authorized users to browse through Internet. The research work addresses some preliminary observations and analyses with the fieldmeasured frequency information from FNET. The original algorithms based on the frequency response characteristic are designed to process event detection, localization and unbalanced power estimation during frequency disturbances. The analysis of historical cases illustrate that these algorithms can be employed in real-time level to provide early alarm of abnormal frequency change to the system operator. The further application is to develop an adaptive under frequency load shedding scheme with the processed information feed in to prevent further frequency decline in power systems after disturbances causing dangerous imbalance between the load and generation.

Power Systems Frequency Dynamic Monitoring System Design and Applications

Dynamics recording devices (DRDs) that monitor and record the transient or dynamic response of power systems are installed across power systems. DRDs that have been installed in the last decade have increasingly used digital computer implementation-these include digital relays, digital fault recorders, integrated electronic controls for substation automation and many digitally implemented controls such as excitation system controls and stabilizers. Here, the authors describe how DRDs and monitoring systems need triggering algorithms and settings that dependably and securely detect unusual events in the presence of normal power system events.

R.P. Schulz

Papers

Triggering tradeoffs for recording dynamics [in power systems]