Grid Performance and Reliability

You are here

As the solar industry moves towards achieving the SunShot goals, the nation's electricity grid must evolve to accommodate increasing amounts of distributed photovoltaic (PV) systems. Effectively interconnecting variable PV generation requires forward thinking and dynamic solutions to ensure compatibility with the existing grid.

What is the Duck Curve?

Projects in the Grid Performance and Reliability activity area focus on achieving high penetrations of solar at the distribution level and on the transmission grid in a safe, reliable, and cost-effective manner. In order to accomplish these goals, the solar office supports:

  • Developing state-of-the-art utility modeling, simulation, and analysis tools to address technical issues surrounding grid planning, operations, and reliability;
  • Developing advanced grid-friendly PV interconnection technologies;
  • Accelerating cost-effective deployment of PV generation on the distribution and transmission grid;
  • Developing validated inverter, solar system planning, operations and feeder models to enhance PV integration analysis techniques;
  • Demonstrating the feasibility of high-penetration PV scenarios under a wide range of system conditions through laboratory and field testing;
  • Advancing interconnection and performance standards and codes to enable high levels of PV integration for grid reliability; and
  • Engaging with industry and stakeholders to inform and receive feedback on PV integration.

As the number of PV installations grows exponentially over time, real and perceived risks to grid reliability, operations and stability create additional barriers in advancing PV deployment. Part of the challenge is the need to deal with additional interconnection, operational impact and complexity. The Grid Performance and Reliability topic area aims to systematically address the challenges and remove the barriers to integrating high penetrations of solar generation at the transmission and distribution levels. The solutions must be cost-effective and ensure the overall safety, reliability and security of the electric grid.

Transmission System Challenges of High Penetration of Solar

  • Grid Operations – cycling and ramping of conventional generation, transmission utilization patterns and generation curtailment
  • Grid Reliability – impact on operating reserves, generation flexibility and grid codes compliance
  • Grid Stability – frequency response and system inertia, large and small scale signal stability
  • Models and Codes – steady state and transient stability models, short circuit and dynamic models, and interconnection-performance standards
  • Grid Operators and Utilities – regulators and adjacent power grids, and analysis derived understanding of PV

Distribution Systems Challenges of High Penetration of Solar

  • Voltage and Var Regulation – maintaining service voltages within the ranges of industry standards
  • Unintentional Islanding – safety hazards for line crews and the public, out-of-phase reclosing, transient overvoltage, and increase restoration time leading to lower system reliability
  • Power Quality – voltage flicker, harmonic distortion, and grounding-related protection issues
  • Protection Coordination – alteration of fault current flows on the distribution system impeding the ability of protection devices to detect and isolate faults, nuisance tripping and potential increases in system outages
  • Distribution Modeling Tools – new quasi static time series analysis tools, interoperability with utility legacy software, model conversion, complex granular data and increased computational time
  • Visibility and Control – real time visualization of distribution feeders, big data analytics, low cost sensors, and back-end hardware system
  • Codes and Standards – state interconnection process, IEEE 1547 series, FERC SGIP, UL1741, NEC and stakeholder engagement

Achieving the Grid Performance and Reliability target metrics in an integrated manner will create a significant and potentially disruptive improvement in the integration of solar generation in the distribution system and transmission grid. Achieving the target values will not only enable faster integration of solar generation into the grid, but also result in more reliable, efficient and cost-effective operation of the electric grid while increasing the penetration level of cleaner renewable energy generation.

Technical Metrics for Grid Performance and Reliability

  • High penetration of solar generation
    • PV penetration > 100% of peak load in a line segment as defined by FERC SGIP
  • Reduce interconnection approval time for solar projects
    • < 1 hr (residential); < 5 days (commercial and utility scale)
  • Reduce interconnection cost for solar projects (excluding hardware mitigation costs)
    • < $100 (residential); <$1,000 (commercial and utility scale)
  • Provide decision support, predictive analytics and economic analysis tools for utility planning and operation
    • Real-time (< 5 sec resolution) analysis, visualization, monitoring and mapping of “Big Data” sets from distribution feeder sensors, SCADA, GIS, CIS (Customer Information System), AMI, OMS (Outage Management System) and others 
    • Optimal sensor placement software tools or apps to minimize cost of distribution sensors and maximize sensor data use for time series analysis
  • Scalability and Interoperability
    • Hardware and software tools must be scalable and dynamically adaptable to any level of PV penetration and must interface seamlessly with utility legacy systems 
  • Maintain or Exceed present and future grid performance standard 
    • > ANSI, IEEE, NERC standards
  • Arizona Public Service: Impacts of High Penetration of PV with Energy Storage at Flagstaff Arizona
  • Clean Power Research: Integration of Behind-the-Meter PV Fleet Forecasts into Utility Grid System Operations
  • Electric Power Research Institute: Operational Simulation Tools and Long Term Strategic Planning for High Penetrations of PV in the Southeastern U.S.
  • ​Florida State University: Modeling and Analysis of High-Penetration PV in Florida
  • Georgia State University: Solar Install Mount Production Labor Equipment Simple Balance of Systems
  • Hawaiian Electric Power Company: Distributed Resource Energy Analysis and Management System (DREAMS) Development for Real-time Grid Operations
  • National Renewable Energy Laboratory: Emerging Technology Characterization
  • National Renewable Energy Laboratory: Improvement and Validation of Solar Systems Modeling Algorithms and Tools
  • National Renewable Energy Laboratory: Increasing Distributed PV Penetration Levels
  • National Renewable Energy Laboratory: Integrated Distribution-Transmission Analysis for Very High Penetration PV Solar
  • National Renewable Energy Laboratory: Modeling and Analysis of High-Penetration PV in California
  • National Renewable Energy Laboratory: RTC NREL - Ops & Buildout
  • National Renewable Energy Laboratory: RTC NREL - Research Tasks 1 & 2
  • National Renewable Energy Laboratory: Solar Integration National Dataset and Operational Analysis Models and Tools Improvement
  • National Renewable Energy Laboratory: Solar Value Analysis and Market Penetration Modeling
  • National Renewable Energy Laboratory: Transmission and Alternatives Analysis and Strategic Stakeholder Engagement
  • Sandia National Laboratories: Accelerating Development of Advanced Inverters
  • Sandia National Laboratories: Advanced Measurement and Analysis of PV Derate Factors
  • Sandia National Laboratories: Advancing Solar Integration on Transmission Systems​
  • Sandia National Laboratories: Characterizing Emerging Photovoltaic Technologies
  • Sandia National Laboratories: Distributed Grid Integration Accelerating Cost-Effective Deployment of Solar Generation on the Distribution Grid
  • Sandia National Laboratories: Dynamic Simulation over Long Time Periods with 100% Solar Generation
  • Sandia National Laboratories: Enhanced Grid Operation and Optimized PV Penetration Utilizing Highly Distributed Sensor Data
  • Sandia National Laboratories: Increasing Prediction Accuracy and Confidence in PV System Performance
  • Sandia National Laboratories: Low-Cost Solar Variability Sensor for Ubiquitous Deployment  
  • Sandia National Laboratories: Optimization of a Virtual Power Plant to Provide Frequency Support
  • Sandia National Laboratories: RTC NM/FL Site
  • Sandia National Laboratories: RTC VT Site
  • Sandia National Laboratories: RTC NV Site
  • Solexel: Development and Productization of High-Efficiency, Low-Cost Building-Integrated Photovoltaic Shingles Using Monocrystalline Silicon Thin Film Solar Cells