Deploying Advanced Technology - Key Success Factors and Applications

Authors: V. Madani, Pacific Gas & Electric, R. King, Mississippi State University, F. Rahmatian and D. Novosel,Quanta Technology, M. Adamiak, General Electric, A. Apostolov, OMICRON electronics

Synchronized measurement technology can support many functions, including enhanced energy management system (EMS), situational awareness, wide-area monitoring, advanced warning systems, protection, and control applications. The technology can also be used for daily system operation and asset performance monitoring. The present state estimation (SE) functions, supported by Supervisory Control and Data Acquisition (SCADA) systems, provide some basic monitoring. Inaccuracies in measurements and system models, absence of redundancy in the measured parameters or statuses in most cases, as well as lack of synchronization and time resolution in the SCADA data, result in limited functionality when more frequent and precise power system measurements are required. Introduction of three-phase Synchrophasor measurements into the EMS opens additional opportunities in operating a balanced system.

The addition of synchrophasor data, typically having several orders of magnitude higher resolution, (i.e., 60 or 120 measurements per second as opposed to current EMS measurement of once every 4 to 8 seconds), can help detect and capture higher speed phenomena in the power system. Also, time synchronization to one micro-second allows for accurate comparison of phase angles across the grid and identification of major disturbances, such as voltage instability and islanding. The synchrophasor technology is identified as the key technology to help detect and prevent wide-spread blackouts across the power system.

The rapid deployment of new synchrophasor applications for reliable and secure operations of power systems is already making progress in the electric utility industry. Several such new generation of applications have moved beyond the conceptual and development stages to the development stage. The synchrophasor applications such as Linear State Estimator (LSE), Oscillation Detection, damping, Voltage Stability indicators, etc. are in deployment stages and clear criteria for parameter set-points for triggering events are required for each application. Enhanced tools to validate results and advanced simulation tools for training are other areas for development. Major initiatives are underway to make synchrophasor data format conform to COMTRADE standards for use with off-line analysis tools.

While plug-and-play of such applications into legacy EMS systems is preferable, the deployment faces many challenges. A Service Oriented Architecture (SOA) based implementation will make it easier to integrate new applications into the EMS.
To establish the “business case” and to identify the problems is a major challenge. The system operators have no time to deal with yet a new application that may provide new insights but is not actionable. An extension of this challenge is the new application should be well integrated into their familiar work environment (e.g. user interface) while offering positive new benefits (easy to use, situational awareness, etc.)

To deploy a practical synchrophasor system, several factors have to be considered. A synchrophasor system consists of a number of elements, including measurement devices known as Phasor Measurement Units (PMUs), data processing and alignment devices referred to as Phasor Data Concentrators (PDCs), various telecommunication devices including routers and switches, telecommunication infrastructure usually spanning over several hundreds of miles, and intelligent functions and software applications running on various computers and processors throughout the synchrophasor system.

A production grade synchrophasor system design and architecture need to satisfy a number of key requirements including cyber security, low-latency, large data throughput (bandwidth), high availability and reliability, and maintainability. Also, consistency amongst all measurements (including measurements during dynamic conditions) and interoperability among devices used are critical for the functions deployed in a wide area system. Accordingly, ensuring accuracy of measurement devices and conformance to requirements is paramount for a well-functioning and sustainable system.

Methodology
Pacific Gas & Electric Co. (PG&E), one of the Department of Energy (DOE) Smart Grid Investment Grant (SGIG) recipients, is implementing a production grade synchrophasor system with resiliency for a disaster recovery infrastructure, with a number of advanced applications, both at the control centers and at the substation level. The objective is to engineer a secure, reliable and sustainable synchrophasor system that supports improved grid operation and business decisions.

The following key functions are supported by the PG&E’s synchrophasor system:

  • Situational Awareness, Visualization and Alarming for Electric Transmission Operators
  • Enhanced Energy Management Systems and State Estimation for current EMS users
  • Linear and Distributed State Estimation
  • Post-Disturbance Event Analysis for Planners and Engineers
  • Voltage Stability Management
  • Operator and Engineering Training, Enhanced Dispatch Training Simulator (DTS)
  • Providing interfaces with EMS and with third parties
  • Cognitive task and performance analysis

To support the process of achieving a reliable and maintainable system, PG&E has established an innovative 3-step process:
1. Development of system requirements and specifications
2. Engineering and implementing a real-time proof-of-concept (POC) performance validation center
3. Full deployment and end-to-end testing

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