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Potential Impacts of Smart Grid on Fire Protection Engineering
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Potential Impacts of Smart Grid on Fire Protection Engineering

By Frederick W. Mowrer, Ph.D., P.E., FSFPE, Lonny Simonian, P.E., Thomas M. Korman, Ph.D., P.E., and David C. Phillips  | Fire Protection Engineering

INTRODUCTION

Historically, the generation, transmission, and distribution of electricity has largely been a one-way process, with electrical service providers sending electricity to consumers with little or no feedback from the consumer sites. That model is changing, however, with the modernization of the electricity delivery system to provide two-way communication between providers and consumers as a means to monitor and, in some cases, regulate electrical distribution. Another change is the more widespread use of on-site electrical generation, distribution, and storage systems.

 

These changes fall under the umbrella of what has become known as the "Smart Grid. " The purpose of this article is to address some of the potential electrical and fire safety impacts of the Smart Grid that were identified as part of a research project conducted at the California Polytechnic State University (Cal Poly) on this topic (see sidebar).

 

WHAT IS A SMART GRID?

Under the Energy Independence and Security Act of 2007, the National Institute of Standards and Technology (NIST) has "primary responsibility to coordinate development of a framework that includes protocols and model standards for information management to achieve interoperability of smart grid devices and systems…."1 Furthermore, NIST defines the term "smart grid" as:1

 

"a modernization of the electricity delivery system so it monitors, protects and automatically optimizes the operation of its interconnected elements – from the central and distributed generator through the high-voltage transmission network and the distribution system, to industrial users and building automation systems, to energy storage installations and to end-use consumers and their thermostats, electric vehicles, appliances and other household devices."

 

In this context, "thermostats, electric vehicles, appliances and other household devices" may be considered "utilization equipment." There are a wide range of energy management applications and electrical service provider interactions, including:

  • On-site generation
  • Demand response
  • Electrical storage
  • Peak demand management
  • Forward power usage estimation
  • Load shedding capability estimation
  • End load monitoring (sub metering)
  • Power quality of service monitoring
  • Utilization of historical energy consumption data
  • Responsive energy control

A Smart Grid Conceptual Model can be portrayed as a set of diagrams and descriptions that are the basis of discussing the characteristics, uses, behavior, interfaces, requirements and standards of the smart grid.1

This conceptual model, shown in Figure 1, provides a context for analysis of interoperation and standards for the development of the smart grid architecture.

 

Figure 1. Smart Grid Conceptual Model1

 

Figure 2. Smart Grid Customer Domain1

 

Within this model, "customers" are defined as the end users of electricity, but they may also generate, store, and manage the use of energy. Traditionally, three types of customers are identified, each with their own domain: residential (home), commercial (building/commercial), and industrial. In addition, the end user may be an institutional customer (such as schools, hospitals, etc.). This project focused on the end user, or customer, in the built environment as shown in Figure 2.

 

Implementation of the smart grid changes the nature of the electrical distribution system in ways that have a number of safety implications, including personnel, electrical, and fire safety. Because of these safety implications, it is important that relevant safety codes and standards, such as the National Electrical Code,2 stay abreast of smart grid developments.

 

Before the smart grid, electrical power distribution to customers was largely a one-way process, with customers receiving electrical power generated at a bulk generation plant which was then transmitted and distributed via the existing grid. Under this scheme, a limited amount of instrumentation data could be transmitted from a customer to the service provider and, in some instances, remote control could be executed, such as remotely turning off residential air conditioners during periods of peak demand.

 

Under the smart grid, electrical power generation and distribution become a two-way process between the customer and the grid. To work effectively and safely, the processes of power generation and distribution, as well as those of instrumentation and control, must be closely coordinated and managed.

 

 
SMART GRID TECHNOLOGIES

Current and emerging smart grid technologies were reviewed and the implications that these technologies may have upon the built environment (such as a facility's safety features) were assessed wherever the National Electrical Code2 (NEC) has jurisdiction. This included all power distribution and control systems throughout a facility. Specific areas of focus were:

  • The electrical service or utility point of connection interface (smart meter)
  • Energy generation and micro-generation systems (such as photovoltaic cells, wind power, micro hydro, emergency and standby generators, and fuel cells)
  • Energy conversion/storage systems (such as batteries, uninterruptible power supplies (UPS), and thermal energy storage)
  • Plug-in vehicles
  • Community energy storage

Customers who adopt smart grid technology gain control over the amount and time of electrical load consumption. For residential customers, the smart meter is typically installed by the utility or service provider, and the customer may acquire additional devices/systems to take advantage of the information and communication provided by the meter.

 

 
For example, if these customers switch to a time-of-use pricing system, they can benefit by shifting non-time-specific loads to cheaper times, optimizing micro-generation systems for maximum output at high price times, and using on-site storage to supply the grid or the home at high-price times. The commercial customer may acquire additional devices/systems to take advantage of the information and communication provided by the meter.

 

Device/System
Description
Possible NEC Issues
Smart Meters A meter that monitors and automatically reports a customer's electricity consumption to the utility. Smart meters may also interface with customer's energy systems and devices to provide the customer with additional information, communications with the utility, and demand response or load shedding triggers.
  • Increased wiring for communications
  • Life-safety circuits must not be affected by load shedding
  • Increased load center wiring
  • Adequate grounding and bonding provisions
  • Sensors for connecting smart meters and major electrical loads
  • Harmonics induced from Class 2 wiring
  • Security systems
  • Life support equipment
Energy Micro-Generation, Co-Generation, and Generation Systems (EMGS) Some grid-connected electricity customers have the ability to generate their own electricity through photovoltaic systems, fuel cells, backup generators, etc. These systems may be used to power the customer's equipment or add energy to the grid, especially during peak hours for economic incentives or to help with load shedding. Currently, however, backup generators are not normally permitted to supply power to the grid.
  • System interconnection requirements
  • Protection for fuel to energy conversion
  • DC from an EMGS to a building
  • Manual disconnect switches
  • Grounding system interconnection
  • Excess generation contingencies
  • Manual override of automatically controlled circuits
  • Use of DC from EMGS by consumers
  • Conversion of DC to AC for use or transmission to the grid
  • Limitations on inverter harmonics
  • Listed/certified equipment
Energy Storage Systems (ESS) Storage systems may be used by customers to reduce demand during peak hours, as a backup in case of grid failure, or as a way to increase the flexibility of renewable energy.
  • Overcharging of storage systems
  • Charging and discharging of ESS
  • DC to AC conversion for use or grid supply
  • Fuel cell placement and clearance
  • Ventilation requirements
  • Fault currents
Plug-In Vehicles These vehicles have an energy storage system on-board. The storage can be charged by connection to the grid and may be able to supply the grid if needed.
  • Battery charging and consumption meter/controller installations
  • Overcharging protection
  • Vehicle-to-Grid storage system charging and discharging
  • Charging and discharging
  • Listed/certified equipment

     

Community Energy Storage (CES) A local energy storage with limited backup time that is available to a small group of customers. CES units allow excess energy from the customers to be captured and later re-dispatched.
  • Voltage flicker provisions
  • CES unit guidelines
  • CES unit placement guidelines
  • Grounding and bonding provisions

Table 1. Summary of Smart Grid Technologies

 

Table 1 provides a summary of theses smart grid technologies and provisions that may need to be addressed by the NEC.

 

REVIEW OF NFPA 70

Based upon an assessment of current and emerging smart grid technologies, a review of the NEC was conducted and NEC sections were identified as candidates for revision. Some of these code sections may require revisions to address smart grid monitoring or control, such as chapter 4, "equipment," and chapter 6, "special equipment," while other code sections may require revisions due to utility interfaces (chapter 1, "general," and chapter 2, "wiring and protection"), emergency power (chapter 7, "special conditions"), or wired/wireless communication (chapter 8, "communication systems").

 

SUMMARY MATRIX

Table 2 links recommended code revisions to technologies that have evolved to prompt the change.

Table 2. Summary Matrix

 

Acknowledgements: Portions of this report are reproduced with permission from the National Electrical Code,2 NFPA 110,3 Emergency and Standby Power Systems, and NFPA 111,4 Stored Electrical Energy Emergency and Standby Power Systems, all of which are Copyright © 2010 National Fire Protection Association. This material is not the complete and official position of NFPA on the reference subject, which is represented solely by the standard in its entirety.

This work was made possible by the Fire Protection Research Foundation (an affiliate of the National Fire Protection Association). The authors are indebted to the project steering committee members, smart grid task group members, and industry representatives for their valuable suggestions.

 

Frederick W. Mowrer, Lonny Simonian, Thomas M. Korman and David Conrad Phillips are with the California Polytechnic State University.

 

Smart Grid and NFPA Electrical Safety Codes and Standards

Project Background

In 2009, NFPA was invited to participate in the National Institute of Standards and Technology (NIST) smart grid rapid standardization initiative to ensure that the safety of built infrastructure was appropriately addressed. This was a proactive initiative to ensure that National Electrical Code2 (NEC) and other NFPA electrical safety standards kept pace with smart grid developments. An NFPA smart grid task force was formed and a grant request submitted to NIST for focused support of task force activity. This included accelerating interoperable codes and standards development for the smart grid. The grant request was approved in the summer of 2010.

Project research objectives included:

  • Technology Review and Safety Assessment of the emerging technologies associated with smart grid implementation and their impacts on the safety features of the built environment
  • Regulatory Development and Needs Assessment of current weaknesses/gaps in the U. S. fire and electrical safety codes and standards which will impede widespread implementation of this technology
  • Roadmaps of needed specific codes and standards development/changes and areas where additional data/research on safety aspects is required

The project has received broad support from the fire protection community. The project steering committee consisted of members representing the National Electrical Manufacturers Association, Underwriters Laboratories Inc., International Association of Electrical Inspectors, International Fire Marshals Association, NEC Correlating Committee, Schneider Electric Company, NIST, National Fire Protection Association, and CSA-International.

A two-day industry workshop was conducted in Washington, D. C., in mid-March of 2011 to review preliminary results and solicit input from leaders within the NFPA safety standards development community on the project. The NEC Smart Grid Task Force also provided comments in consideration of the upcoming NEC code-change cycle.

The outcomes of the project included:

  • The final report,5 which is available for free download at nfpa.org/foundation
    – This will form the technical basis for submitted NEC changes related to the smart grid
  • A 20-page inspector's guide6
  • Presentations at IAEI section meetings
  • Plans for future webinars

 

References:

  1. "Report to NIST on the Smart Grid Interoperability Standards Roadmap," Electric Power Research Institute (EPRI), Palo Alto, CA, 2009.
  2. NFPA 70, National Electrical Code, National Fire Protection Association, Quincy, MA, 2011.
  3. NFPA 110, Standard for Emergency and Standby Power Systems, National Fire Protection Association, Quincy, MA, 2010.
  4. NFPA 111, Standard on Stored Electrical Energy Emergency and Standby Power Systems, National Fire Protection Association, Quincy, MA, 2010.
  5. Simonian, L., Korman, T., Mowrer, F. & Phillips, D. "Smart Grid and NFPA Electrical Safety Codes and Standards," Fire Protection Research Foundation, Quincy, MA, 2011.
  6. "A Guide for the Electrical Inspection Community," Fire Protection Research Foundation, Quincy, MA, 2011.
  7. NFPA 70E, Standard for Electrical Safety in the Workplace®, National Fire Protection Association, Quincy, MA, 2012.

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