Editorial

by Alex Apostolov, Editor-in-Chief

Synchrophasors Are Here - It is Time to Use Them!

Synchrophasor measurement devices have been around for more than twenty years. At the beginning they were exotic devices installed in a very small number of locations by utilities that were trying to find better ways to monitor and control the state of the electric power system.

Today things are different. The developments of multifunctional intelligent electronic devices for protection and other applications that perform synchrophasor calculations, as well as the improvements in inter and intra-substation communications bring the industry to a time when many specialists are thinking about the use of synchrophasors for different protection, automation and control applications.

This issue of the PAC World magazine focuses on current and future applications of synchrophasors. The fact that we have articles covering different aspects of the application of synchrophasors in the electric power industry in several continents demonstrates the trend in growing acceptance of this technology as a result of better understanding of its impact on the industry.

The transition from visualization of synchrophasors and support of state estimation to their use for situational awareness, system integrity protection schemes and potentially even for protection applications in the future is driven by the developments of synchrophasors related standards and the increased levels of functional integration in protection and control IEDs.
The old IEEE C37.118 standard is now split in two parts in order to make it easier to harmonize the work with IEC which has different technical committees covering the measurement aspects and the communications.

The first part of the new standard is C37.118.1-2011 - IEEE Standard for Synchrophasor Measurements for Power System. This standard defines synchrophasors, frequency, and rate of change of frequency (ROCOF) measurement under all operating conditions. It specifies methods for evaluating these measurements and requirements for compliance with the standard under both steady-state and dynamic conditions. Time tag and synchronization requirements are included. Performance requirements are confirmed with a reference model, provided in detail. This document also defines a phasor measurement unit (PMU), which can be a stand-alone physical unit or a functional unit within another physical unit, supporting the integration of synchrophasor measurements in multifunctional IEDs.

This standard for the first time introduces two performance classes. As the letter indicates, the P class is intended for protection types of applications requiring fast response which does not require explicit filtering. On the other hand, the M class is intended for measurement applications which could be adversely affected by aliased signals but do not require the fastest reporting speed, thus the M class requires anti-alias filtering. All standard compliance requirements are specified by the performance classes.

The second part of the new standard C37.118.2-2011 - IEEE Standard for Synchrophasor Data Transfer for Power Systems specifies a method for real-time exchange of synchrophasor measurement data between power system equipment. It specifies messaging that can be used with any suitable communication protocol for real-time communication between phasor measurement units (PMU), phasor data concentrators (PDC), and other applications. It defines message types, contents, and use. Data types and formats are specified and a typical measurement system is described. Communication options and requirements are described in annexes. The standard defines the formats for frames sent out from the PMU (data, configuration, and header) and for command frames sent to the PMU, together with mappings to serial communication and to TCP/UDP.

All of the above, together with the Technical Report IEC 61850 90-5 Use of IEC 61850 to transmit synchrophasor information according to IEEE C37.118 creates an environment for development and implementation of many new synchrophasor applications that can move the electric power industry in the direction of steady state system monitoring, adaptive wide area protection and other advanced PAC applications.

"If we do not change our direction, we are likely to end up where we are headed."
Chinese Proverb

Let?s start with organization in protection testing