This paper discusses the major features and design objectives of the IEEE-1588 standard. Recent performance results of prototype implementations of this standard in an Ethernet environment are presented. Potential areas of application of this standard are outlined.

IEEE 1588 standard for a precision clock synchronization protocol for networked measurement and control systems

IEEE Standard 1344, Synchrophasors for Power Systems, was completed in 1995. It sets parameters required to ensure that phasor measurement will be made and communicated in a consistent manner. It specifies requirements for the timing signal used for phasor synchronization and the time code needed for input to a measurement unit. GPS is the recommended time source and IRIG-B is the basic format used for time communication. The standard requires correlating phasors computed from unsynchronized and synchronized sampling to a common basis. Timetagging accurately and consistently is essential for wide area comparison of phase. The standard specifies information exchange and control message formats. These include data output, configuration, and command messages. It includes 7 annexes that discuss the concepts covered in the body of the standard.

IEEE Standard for Synchrophasors for Power Systems

This paper proposes a method for optimal placement of phasor measurement units (PMUs) for complete observability of a power system for normal operating conditions, as well as for single branch outages. A binary search algorithm is used to determine the minimum number of PMUs needed to make the system observable. In case of more than one solution, a strategy is proposed to select the solution resulting in the most preferred pattern of measurement redundancy. The proposed method is used to benchmark the optimal PMU placement solutions for the IEEE 14-bus, IEEE 24-bus, IEEE 30-bus and New England 39-bus test systems. The proposed method is applied on a 298-bus system to determine the optimal placement of PMUs when conventional measurements are available.

Optimal Placement of Phasor Measurement Units for Power System Observability

As background, we describe frequently used feedforward wide-area discontinuous power system stability controls. Then we describe online demonstration of a new response-based (feedback) Wide-Area stability and voltage Control System (WACS). The control system uses powerful discontinuous actions for power system stabilization. The control system comprises phasor measurements at many substations, fiber-optic communications, real-time deterministic computers, and transfer trip output signals to circuit breakers at many other substations and power plants. Finally, we describe future development of WACS. WACS is developed as a flexible platform to prevent blackouts and facilitate electrical commerce.

WACS-Wide-Area Stability and Voltage Control System: R&D and Online Demonstration

Evaluation of the vulnerability of phasor measurement units to GPS spoofing attacks

This paper describes the concept of utilizing time synchronized sampling over an entire power system to simultaneously obtain the phasor values of voltages and currents at particular instants of time. Uses of the phasors are reviewed and the necessary accuracy of synchronization for several applications is established for magnitude and angle of the phasors. Various methods of providing synchronizing signals are examined, and a possible format for transmitting the phasor measurements to remote locations is described. Finally, some possibilities for applications of this technique in protection and control tasks of the future are explored. >

M.A. Xavier

Papers

Synchronized sampling and phasor measurements for relaying and control