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Electric Power Metrology and the Smart Grid

Summary

Our country's way of life depends on the electric power distribution system. Keeping the national electric grid in good working order -- and ensuring power is measured accurately and billed fairly -- requires a set of standards for electric power measurements. NIST is deeply involved in developing and maintaining these standards. Our efforts include devising metrology that allows new technologies to connect into existing power production and delivery systems, as well as standards that protect the infrastructure from potential dangers introduced by deregulation. This project's work also supports the realization of the Smart Grid, the future model of the U.S. electric power grid that incorporates cutting-edge technologies to achieve unprecedented efficiency, reliability, and safety.

Description

Allen Goldstein

Figure 1. Allen Goldstein with the NIST PMU Calibrator Calibration System

Major advancements in electric power generation, transmission, distribution and loads over the last 20 years have led to improvements, reliability, robustness, efficiency and energy security unlike anything from the proceeding 80 years. Combined, this power grid modernization has been called the “smart grid” due to reliance on computing communications techniques. With modern challenges such as increasing demand for electrical power, increasingly severe weather events, transitions from centralized, remote generation resources to distributed generation, and local and regional mandates to transition to renewable energy sources, the advancement in grid technology is accelerating.

Physical Measurements are at the heart of the smart grid. And measurement is the heart of the NIST Physical Measurement Laboratory mission. Power grid modernization requires measurements to be made more often and with increasing accuracy. The modern power system presents new measurement challenges such as switching noise from inverter-based resources, increasingly dynamic power swings and modern generation, load balancing, and protection schemes. New, wide area monitoring, protection and control has created a new metrological field: synchrometrology – the science of time-synchronized measurement.

The NIST Synchrometrology Laboratory researches synchronized measurements and instrument calibration techniques, collaborates with laboratories, industry, academia and other government agencies in the development of measuremtns techniques and with international standard setting organizations in the creation and revision of standards, guides and reports. The Synchrometrology Lab also provides traceability for the international synchrophasor performance conformity assessment program laboratories through our PMU Calibrator Calibration service.

Smart Grid Testbed
Figure 2. NIST Smart Grid Testbed Power Conditioning System Schematic
Watthour Meter Testing
Watthour Meter Testing

PML collaborates with the NIST Smart Grid Program to provide project leadership of the NIST Smart Grid Testbed Power Conditioning System, a  microgrid test bed designed for measurement, protection, and control research of grid connected inverter based resources.

Power outages are at a minimum an inconvenience, but extended periods without power can be life-threatening; e.g., to patients in hospitals and during extreme weather. The introduction of renewable resources within the U.S. electric power industry has complicated the task of ensuring the dependability of the nation's complex power infrastructure. NIST performs invaluable research that supports reliable power delivery, public safety, and accurate pricing of electric power.

Recent advances are making this task increasingly difficult. Modern technology has opened the door to suppliers using non-traditional electricity generation technologies that may introduce distortions into the flow of power delivered to customers. NIST is developing systems to characterize the distortions and verify that meters can still operate accurately even when these distortions are present.

Permuting Resistive Divider
Permuting Resistive Divider

To remain competitive in the global power market, U.S. industry needs standards that are internationally acceptable. International comparisons are essential for the validation of measurement techniques used at national metrology institutes across the globe and also for transnational sales of electric power. The Electric Power Metrology group is at the forefront of addressing these concerns through quantum based measurements and references, phasor measurement and calibration of phasor measurement units (PMUs), renewable and distributed energy source research, and power calibration services to validate digital multimeters (DMMs), current transformers (CTs), and other power energy solutions.  

Enabling higher levels of penetration of variable, renewable energy sources such as wind and solar PV, requires precise, low-latency, time-referenced voltage, current, and power measurements on the transmission and distribution system in order to prevent system instabilities.  These types of measurements are also necessary to enable the development of controls for smart inverter based resources.

Major Accomplishments

  • PJVS Referenced Power Measurement System
    PJVS Referenced Power Measurement System
    Developed hardware and software to test more secure control system communication techniques and to make sure that these techniques meet the relevant standards
  • Served as the pilot lab for a comparison among countries that participate in the Interamerican Metrology System
  • Performed essential electric power metrology for the Smart Grid, a model for the modernization of electric power production and distribution. The Smart Grid will be more reliable, efficient, and safer than today's grid.
  • Developed quantum-referenced power generation system that accurately relates the voltage and current signals of the generated phantom power to either a programmable Josephson voltage standard (PJVS) or a Josephson array waveform synthesizer (JAWS).
  • Developed hardware and software to support the calibration of distorted power calibrators and analyzers.
  • Developed improved measurement services to support the calibration of ac current and voltage transducers.
  • Calibration services that are covered in the project are:
    • DMMS
    • PHASE
    • VOR
    • POWER AND ENERGY METERS
    • CURRENT TRANSFORMERS
    • DC HIGH VOLTAGE DVIDERS
    • PMU CALIBRATORS
    • QUANTUM BASED MEASUREMENTS / REFERENCES
Created November 21, 2008, Updated May 11, 2021