Frequency dynamics is one of the most important measures of an electrical power system status. To better understand power system dynamics, an accurately measured wide-area frequency is needed. The concept of building an Internet-based real-time GPS-synchronized wide-area frequency monitoring network (FNET) was proposed in 2000 by Qiu et al., and this concept has been realized. The FNET system consists of frequency disturbance recorders and an information management system. The FNET has made the synchronized observations of the entire U.S. power network possible with very little cost for the first time. This paper summarizes the implementation of the FNET system and shows some preliminary observations and analyses of the data that have been collected from the FNET.

Power system frequency monitoring network (FNET) implementation

A real-time performance monitoring system for monitoring an electric power grid. The electric power grid has a plurality of grid portions, each grid portion corresponding to one of a plurality of control areas. The real-time performance monitoring system includes a monitor computer for monitoring at least one of reliability metrics, generation metrics, transmission metrics, suppliers metrics, grid infrastructure security metrics, and markets metrics for the electric power grid. The data for metrics being monitored by the monitor computer are stored in a data base, and a visualization of the metrics is displayed on at least one display computer having a monitor. The at least one display computer in one said control area enables an operator to monitor the grid portion corresponding to a different said control area.

Real-time performance monitoring and management system

Wide-area, real-time monitoring and visualization system

The subject specification comprises a generalized grid security platform (GGSP) that can control power distribution and operations in a power transmission and distribution grid (PTDG) in real or near real time. The GGSP can receive data from one or more data sources, including a PMU(s) or an IED(s), which can obtain power system related data and provide at least a portion of such data to the GGSP at a subsecond rate. The GGSP can correlate data from the data sources based at least in part on a temporal, geographical, or topological axis. The GGSP can analyze the data, including performing predictive analysis, e.g., via simulation, root cause analysis, post mortem analysis, or complex event processing, when desired, to facilitate identifying a current or predicted future state of the PTDG, a cause or source of an abnormal condition, or a remedial action execution plan, new operation or maintenance guidance, etc.

Generalized grid security framework

This paper recalls the 30-year history of wide-area measurements at Hydro-Quebec. At present, a state-of-the art, eight-PMU-based wide-area monitoring system commissioned in 2004 is on line, feeding the EMS with GPS-synchronized angles, frequencies, and harmonic distortion measurements from key 735-kV buses. Specific to Hydro-Quebec is the current use of one such system for frequency regulation reporting and control-room implementation of preventive measures against geomagnetic storm-induced contingencies. Building on this experience, the Hydro-Quebec research institute, together with TransEnergie, is developing advanced applications which, in the long term, will go beyond active monitoring to safely initiate targeted control actions aimed at extending system power transfer limits with respect to both transient and long-term stability. In addition to the major improvement in inter-area mode damping shown previously by the authors, this paper demonstrates that, surprisingly, wide-area control of static VAr compensators (SVC) will also vastly extend the first-swing stability margins. Finally, initial results on a wide-area measurement-based secondary voltage control of the extensive park of dynamic shunt compensators in our grid using a single pilot voltage from the load center are very encouraging.

Wide-area monitoring and control at Hydro-Quebec: past, present and future

The disclosure relates to phasor-based monitoring, protection and control applications in electric power systems supervised and/or managed by a Supervisory Control And Data Acquisition/Energy Management System (SCADA/EMS). In order to enable the applications without incurring heavy infrastructural investments, a phasor measurement facility is integrated into a Remote Terminal Unit (RTU) that is part of the SCADA/EMS system and comprises Input/Output (I/O) interfaces hard-wired to a substation of an electric power system. By taking advantage of the fact that RTUs as indispensable building blocks for any SCADA/EMS are part of every substation of the power system, no extra housing, cabling and EMC shielding for the additional functionality needs to be provided.

Remote terminal unit and monitoring, protection and control of power systems

With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming increasingly important. This requires information with higher accuracy and update rates faster than those usually provided by traditional SCADA systems. In addition, it must be synchronized over a wider geographical area than that provided by traditional protection systems. The introduction of phasor measurement units as well as advances in communication and computational equipment have made it technically feasible to monitor the stability of the power system on-line, using a wide area perspective. This paper outlines the specialized applications to monitor and control voltage as well as frequency stability of power systems and describes their state-of-the-art platform, the wide-area measurement system, which is now commercially available.

Experiences with and perspectives of the system for wide area monitoring of power systems

The present disclosure is concerned with the reduction of an operational security margin of a power system without jeopardizing the safety of the power system or incurring heavy investments. According to the disclosure, a check for basic accuracy or correctness of a conventional State Estimation (SE) procedure allows to increase a level of confidence in the results of the procedure. To this end, an accuracy of the estimated states is verified by comparing the latter with the results (y, y′) of independent phasor measurements performed at selected locations of the power system. Unless a discrepancy is reported by this comparison, the results of the SE can be assumed to be sufficiently accurate, and any conservative or additional security margin intended to compensate for SE uncertainty can be relaxed. Hence, established trustworthiness in the estimated states allows increasing the transmitted power where the estimated states do indicate such a possibility, i.e. in particular in fringe areas and/or transmission corridors between countries, and especially under stressed network conditions.

Verifying an accuracy of a state estimation

The present invention is concerned with the reduction of an operational security margin of a power system (1) without jeopardizing the safety of the power system or incurring heavy investments. According to the invention, a check for basic accuracy or correctness of a conventional State Estimation (SE) procedure allows to increase a level of confidence in the results of the procedure. To this end, an accuracy of the estimated states is verified by comparing the latter with the results (y, y´) of independent phasor measurements performed at selected locations (B, D) of the power system. Unless a discrepancy is reported by this comparison, the results of the SE can be assumed to be sufficiently accurate, and any conservative or additional security margin intended to compensate for SE uncertainty can be relaxed. Hence, established trustworthiness in the estimated states allows increasing the transmitted power where the estimated states do indicate such a possibility, i.e. in particular in fringe areas and/or transmission corridors between countries, and especially under stressed network conditions.

Andreas Suranyi

Papers

Remote terminal unit and monitoring, protection and control of power systems

Experiences with and perspectives of the system for wide area monitoring of power systems

Verifying an accuracy of a state estimation

Method and apparatus for verifying the accuracy of state estimation calculations

Terminal à distance, surveillance, protection et commande de systèmes de puissance