13.5: Smart Grid Technology

With the introduction of distributed generation (DG), renewable generation, and PEVs, evidence of adverse impacts on grid operation is surfacing. These impacts include curtailed solar and wind, and increasing challenges in managing intermittent solar and wind—for example, by buffering intermittencies and by increasingly high afternoon ramp rates to augment the loss of solar late in the afternoon when loads increase. Arguably, to accommodate and manage DG, renewable generation, and PEV penetration, major changes in the operation of the grid must be developed and implemented. The deployment of DG and associated distributed energy resources (DER) such as energy storage requires visibility to, and control over, this new paradigm. Increasing the penetration of intermittent renewable resources requires an accurate forecasting of intermittent solar and wind resources, as well as a methodology to handle the uncertainty that these resources introduce into the modeling, planning, and operation of the system. Managing a high penetration of PEVs requires more visibility into the distribution system so that their impact on the load profile can be managed and they can be used as a grid resource for providing energy and ancillary services. Such “visibility” (that is, the amount and resolution of information that is accessible to system managers) includes real-time operating information on individual transformers.

Smart grid technology is emerging as a major strategy to handle these challenges. A smart grid is a grid with the intelligence to (1) maintain (and increase) the efficiency and reliability of the grid, (2) provide the grid operator with visibility and remote control of the system components through sensing throughout the transmission and distribution network, and (3) provide two-way communication and controls to enable a path for grid automation and electricity markets participation.

California provides an example of where the smart grid is emerging, with a focus on four major levels (Figure 13.5.1):

Figure 13.5.1 Smart grid.

• Consumer level: Facility energy management and control by residential owner, office building manager, industrial plant manager, or campus microgrid operator.
• PEV level: Automobile manufacturer and/or utility management schemes, control of PEV charging (smart charging), and potential V2G energy storage recovery.
• Utility level: Utility management and control of distribution system services and resources.
• Independent system operator (ISO) level: ISO management and control of the full portfolio of grid services and resources, including electricity markets, to ensure that loads are balanced and that supply is reliable and sufficient to meet the grid dynamics, namely load changes and rate of the load changes.

Smart grid technology in the country has developed and improved significantly during the past decade through investment in research and demonstration projects such as the California Public Utilities Commission’s smart grid investment plan and the US Department of Energy’s Irvine Smart Grid Demonstration program. These efforts resulted in advances and deployment of smart metering, smart appliances, automated substations and other distribution system upgrades, advanced sensing and controls, high-speed communications, smart inverters, and smart switches. The broad deployment of smart grid technology faces challenges, including these examples:

• Interoperability: A smart grid requires the various components of the system to communicate with one another or at least a central controller/operator. To achieve this, communication protocols, standards, and a robust communication infrastructure must be developed upon which vendors, utilities, and regulatory agencies can agree and comply.
• Reliability and cost: The reliability of the system must be ensured without having excessive redundancy, in order to minimize the overall cost of the system.
• Data management: The collection of high-resolution data is required to obtain an accurate picture of the system status and also verify the system load flow and transient models.
• Cybersecurity: As the system moves toward automation and remote control, the system must be secured through cybersecurity measures and encrypted communications.
• Too much change, too quickly: The smart grid paradigm will dramatically change the roles of utilities, independent system operators, aggregators, and service providers in a relatively short amount of time. Therefore, it is prudent to develop road maps and guidelines for the industry to follow and prepare for their revised roles. For example, with more distributed energy resources, the role of the utility changes from delivering energy to providing ancillary services and backup and/or serving as an aggregator of distributed energy resources.
• Development of a wholesale electricity market: First, the generating resource needs to establish an agreement with the utility to access the transmission system. Today this is done through wholesale distribution access tariffs (WDATs.) Second, the grid operators need to allow the distributed energy resources (DER) to participate in the market. This will present challenges since the DER can be very flexible (compared with conventional generation and even renewable resources) and are located deep in the distribution system where the ISOs do not have visibility.

To achieve the compelling potential attributes of smart grids and microgrids (for example, high efficiency, lower GHG and criteria pollutant emissions, lower operating costs, the accommodation of grid ancillary and emergency services, and the ability to enable and expand the evolving electricity), research is required to advance smart communications, controls, energy storage, high-resolution and robust sensors, power electronics, load-following and high-ramping 24/7 clean power generation, smart PEV charging/discharging, and energy management systems. In parallel, research is required to establish and implement policies that support the development and deployment of the empowered concomitant electricity markets.