California Utilities Define New Smart Inverter Capabilities | IEEE Smart Grid Newsletter

Jun 13, 2019 | Article

California Utilities Define New Smart Inverter Capabilities
Originally published in the IEEE Smart Grid June 2019 Newsletter

Kay Stefferud, Director of Implementation Services
kay@enernex.com
865-770-4867

 

 

California’s phased implementation of smart inverter functionality addresses power quality issues including issues caused by independent and intermittent renewable energy sources. Recommendations from California’s Smart Inverter Working Group (SIWG) enable smart inverters to improve power quality. Inverters can be harnessed to improve power quality including rapidly changing production caused by clouds moving over solar PV sites. Previously per IEEE 1547, inverters were required to disconnect from the grid when power quality issues arose. Recent changes in IEEE 1547-2018 and the corresponding aligned state interconnection requirements now require smart inverters to sense grid conditions and respond accordingly. Smart inverters can positively impact the utility grid, or at the minimum leave the grid unaffected. Smart inverters are also capable of receiving signals from the utility to support the utility’s distribution system.

Phase 1 Functions

  • Anti-Islanding Protection
  • Low and High Voltage Ride-Through
  • Low and High Frequency Ride-Through
  • Dynamic Volt-Var Operation
  • Ramp Rates
  • Fixed Power Factor
  • Soft Start Reconnection

Phase 2 Recommendations

  • Smart inverters communicate with the utility through:
    • Direct DER Communications – individual DER systems linked directly to the utility.
    • Aggregator Mediated Communications – approved third parties that combine multiple DER systems

Phase 3 Functions

  • Monitor Key DER Data
  • DER Disconnect and Reconnect Command (Cease to Energize and Return to Service)
  • Limit Maximum Active Power Mode
  • Set Active Power Mode
  • Frequency Watt Mode
  • Volt Watt Mode
  • Dynamic Reactive Support
  • Scheduling Power Values and Modes

Previous standards required inverters to disconnect from the grid when system disturbances caused voltage and frequency to go outside of a specified band. The subsequent abrupt net demand change can be problematic on circuits with large amounts of inverter-enabled distributed generation. Phase 1 capabilities such as low/high voltage ride-through and low/high frequency ride-through instruct smart inverters to continue generating despite momentary/temporary voltage and frequency fluctuations.

With the Phase 3 Frequency-Watt function, generators with smart inverters are required to adjust active power generation as a function of frequency. Normal frequency operation is from 59.964 Hz to 60.036 Hz (within +/- 0.036 from 60Hz). During normal operation, smart inverters are not required to decrease or increase active power production. When the frequency goes over 60.036Hz, smart inverters are required to reduce active power at a rate of 50% of real power nameplate rating per Hz. As active power injection is beneficial at lower band frequencies, smart inverters can increase active power production by 50% of real power nameplate rating per Hz when possible. Similar to the Frequency-Watt settings, active power generation will also be adjusted as a function of voltage at the inverter terminal or the Point of Common Coupling (PCC). Active power adjustment is relative to the export of active power to the grid, and not the smart inverter’s overall active power production. Effectively, there is no limit on customer generation if they are using all the power generated. Active power production will be reduced by 25% of the active power nameplate per 1% of nominal voltage when the measured voltage is greater than 106% of the nominal voltage. Cut-off of generation occurs at 110% of nominal voltage, and the smart inverter reduces generation to 0 W.

Using dynamic volt-var operation, smart inverters are permitted to operate within a range of power factor values to provide reactive power support. Smart inverters respond to grid conditions and provide reactive support within the acceptable range of power factor values. Fixed power factor entails providing a power factor setting to smart inverters based on identified reactive power needs on a circuit.

Phase 2 recommendations guide utilities on communications with smart inverters. Communications enable utilities to send commands to smart inverters, including signals that can positively impact power quality. Utilities should be able to communicate directly with individual smart inverters, through Facility DER Energy Management Systems (FDERMS), and through Retail Energy Providers/Aggregators/Fleet Operators. Commands sent by utilities to smart inverters can enhance power quality. The commands can be particularly beneficial during grid distress periods. Commands identified by the SIWG include: “Cease to energize control command,” “Return to service control command,” “Limit active power command,” “Set active power level mode function,” and “Suspension of active power restriction.”

The “Monitor Key DER Data” function communicates performance information (smart inverter production or consumption of active and reactive power, phase voltages, and frequency) and operational state information (in-service or not in-service). The performance and operational state information provided by smart inverters enhances the utility’s situational awareness.

California’s smart inverter functions can address power quality concerns as described above. We will continue to follow the activities of the California Public Utilities Commission, SIWG, and utilities on power quality applications of smart inverters.

Smart Metering (SM) and Advanced Metering Infrastructure (AMI)

Smart Metering and AMI is a transformational process addressing multiple business and technical needs of the utility enterprise. This is more than just smart meters and communications networks; it includes all of the back end applications that can leverage the meter assets, such as outage notification, demand response, call center optimization, disputed billing process handling, pre-payment opportunities, and service connection management methods and procedures, to name a few.

Implementing SM and AMI faces the same business, engineering, and operational challenges as any other across-the-utility information technology endeavors – most notably risk associated with embracing proprietary technology, missing functionality and early obsolescence. Effective SM and AMI development, implementation, and operation relies on a marriage of electric power engineering with information technology expertise: a key component of EnerNex’s expertise and experience.

EnerNex provides an array of engineering and consulting services geared towards intelligent and effective implementation of SM and AMI. This covers all phases of project development, starting with capturing system requirements where our experts leverage a “Use Case” centric view of activities needed to be accomplished and their interaction with systems and other users. Subsequent project steps typically examine other critical areas, such as: modeling of business cases, building inter-department consensus, assembling and assessing system functional requirements and non-functional requirements, developing a system design, hardware and software specifications and standards, complete procurement services including RFI and RFQ process support, supplier rating system, response evaluation methodology, deployment management, and training of office and field personnel.

Demand Response (DR)

Demand response can be as simple as load interruption directed by the energy supplier in response to severe demand requirements, to complex customer defined load management in response to price signals. DR is one of the components of a “Non-Wires Alternative” that many utilities are effectively using to avoid expensive distribution fortification or upgrade.

 

Often the success and/or failure of demand response programs can be linked to program implementation challenges such as rate/tariff design rate structures communication (e.g. price signals) or ineffective incentives used by utilities to encourage customers to accept operational change. The issues of program design, rate structure and customer impact have a tremendous influence on the success or failure of load management initiatives. Demand response has traditionally been used as a tool of the energy industry to ensure system stability. However, the introduction of microelectronics, communications, home automation and the Internet of Things (IoT) has led to the development of cost effective solutions that have the capability to allow the consumer to take control of managing their energy load and ultimately, the price they pay for energy.

EnerNex has the experience and skills to turn your DR program into a successful operational asset and customer engagement process that can deliver value to all parties.

Energy Assurance Planning

Natural and man-made disasters cause an estimated $57B in average annual costs for all parties; large single events have resulted in losses of $100B or more. Events, such as the World Trade Center disaster, Hurricane Katrina, and most recently Hurricane Helene, have demonstrated an acute need to revisit, revise and implement an effective energy assurance plan. Energy assurance plans assess the functionality and interdependencies of buildings and infrastructure systems and the role they play in sustaining service and rapidly restoring critical services to a community following a hazard event.

 

EnerNex assists our clients in developing comprehensive energy assurance plans that mitigate and minimize the impact of energy disruptions. Our experts assess critical infrastructure risks and evaluate appropriate mitigation strategies and can help in developing an effective business continuity/disaster recovery (BC/DR) plan for utilities and your customers.

Microgrid Development

As the electric grid becomes more distributed and interactive, microgrids are playing an increasingly important role in our energy future. Decision makers at military bases, corporate and institutional campuses, residential communities and critical facilities across the world are exploring and implementing microgrids to meet economic, resiliency and environmental goals. Utility-grade microgrids are being deployed to meet transmission constraints, reliability requirements and safe-havens in the event of a significant storm event.

Microgrid_development Graphic steps to support grid modernization

Bringing together a portfolio of distributed energy resources into a controllable, islandable microgrid comes with its own set of challenges. The key to solving these challenges is in architecting a system to support information exchanges between components across well-defined points of interoperability (interfaces) in a technology independent manner. This interoperability ensures that the system is resilient to technology change. Modern systems engineering techniques must be employed to ensure that individual sub‐systems are clearly identified, their functions enumerated, their data requirements known, and the points of interoperability clearly specified, along with the commensurate monitoring, command and control that is needed to ensure grid stability. With such architecture, we can apply best of breed technology available today to support those information exchanges at interface boundaries but be free to upgrade / change the implementation technology later without causing a ripple effect throughout the system.

Enterprise Architecture

Enterprise Architecture focuses on aligning an organization’s business strategies with its anticipated, desired and planned technology enhancements. Enterprise Architecture provides a framework to cost-effectively transition from a current “as-is” technology to future enterprise-wide technological solutions. An effective Enterprise Architecture program aligns business investments with long-term business strategies while minimizing risk and providing superior technological solutions. EnerNex’s key asset is its highly skilled and experienced staff who are closely connected to both the smart grid and EA standards and practices. We provide clients with the insight necessary to operate a fully functioning smart grid, which is flexible, scalable, and vendor independent.

Grid Modernization Roadmap

Utility companies across the globe are continually modernizing their grid. Each company often has different rationales, objectives and priorities. Frequently, smart grid plans are developed for individual, incremental initiatives, rather than as a part of a whole, intelligent and interoperable infrastructure. Planning may be developed around technology choices rather than business and technical requirements. The result of incremental and flawed planning leads to increased cost and risk, lost opportunities, disconnected expectations and dead ends.

 

EnerNex’s approach to grid modernization roadmap development follows a proven, industry-standard approach to grid modernization planning by collaboratively working with the utility to develop a set of prioritized and time-phased grid modernization initiatives unique to its business strategy and objectives. The roadmap developed is holistic, requirements-based, business value driven and actionable. It often builds on and leverages existing applications and infrastructure, and incorporates industry standards to ensure interoperability, flexibility and reduced cost and risk.

Utility Communications

Utility communication and control systems are increasingly interconnected to each other and to public networks and as a result, they are becoming increasingly more susceptible to disruptions and cyber attacks. EnerNex has experience with the various issues relating to development, implementation and optimization including feasibility analysis, design, software development and customization, project management and acceptance. Our expertise extends from being involved in the development of the fundamental standards that support utility communication and automation, through deployment and securing of those resources. EnerNex personnel were heavily involved in development of such standards and protocols as IEC 61850, IEC 60870-5 and DNp3. Our staff played a key role in the EPRI Utility Communication Architecture (UCA) project and the IntelliGrid Architecture effort.

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