The electric energy grid is facing a major transition as it moves to the next generation of energy production, transmission, and distribution. In the coming decade, distributed renewable energy sources will expand, electrification of energy consumption will increase, and electric vehicle ownership will grow in popularity. As the electric grid is modernized, new components must be introduced to maximize facility safety, reliability, and security, while increasing overall maintainability and reducing infrastructure costs.
Today’s aging substations must be replaced with electric warehouses, and transmission lines upgraded to powerways. Distribution lines should be updated to become serviceways, designed to accommodate bidirectional electric vehicle chargers and distributed energy resources. These enhanced designs will not require a total overhaul of existing grid components; rather, new components can be phased in over time or added to existing facilities. Once new components are designed, the cost to manufacture these modern components will be in line with today’s costs.
Electric Warehouses: Tomorrow’s Substations
Electric warehouses will be a modern, cost-effective alternative to today’s substations. The exterior of electric warehouses will be a low-profile building that blends in with surrounding buildings, which will enhance the security of these next generation substations. Inside, standardized, modular components will replace components that, today, are often unique to the electric utility or region of the country. These modular components can be quickly assembled inside the building within 60 days of completed building construction.
Standardized, modular components will reduce costs and enhance constructability of electric warehouses. Because components will be the same across the US, component availability will increase. This means that new electric warehouses can be constructed quickly with readily available components, and any failed components can easily be replaced within seven days of the failure.
With component standardization, electric warehouses will look the same inside the building no matter where they are located. For example, all high voltage circuit breakers will be designed so that they can be racked together in the same way that 13.8 KV switchgear is assembled. Other standardized components may include switchgear that is categorized by voltage and amps, for example, 15 KV type 1 (1000 amp), type 2 (2000 amp), type 3 (3000 amp) and 242 KV, type 2 (2000 amp), type 3 (3000 amp), Type 4 (4000 amp). Also, 242 KV / 72 KV transformers can be standardized by Mega Volt Amp (MVA): type 1 (125 MVA), type 2 (250 MVA), and type 3 (375 MVA).
Electric warehouses will have capabilities beyond those of today’s substations. Each neighborhood electric warehouse will be able to provide energy for up to four hours when connection to the power grid is lost. Energy can be provided either via storage technology, such as a large-scale battery, or in combination with distributed energy resources and electric vehicles connected to the electric warehouse. To meet the four-hour mark, a neighborhood electric warehouse with 15 KV, Type 1 switchgear should be able to access 100 MWH of stored energy. Note, stored energy will also be used to reduce load on the grid during peak load conditions.
Powerways: Next Generation Transmission Lines
Powerways will be inherently safer and more robust versions of today’s transmission lines. To create AC powerways, a few new components will be added to transmission lines: series capacitors or series reactors, depending on the length of the line, as well as solenoid type series reactors. Figure 1 shows a one-line diagram of a transmission line. Figure 2 shows the same transmission line after new components have been installed, transitioning it to a powerway.
Series capacitors will reduce line impedance and increase energy transfer on powerways that are more than 20 miles long. Series reactors will increase line impedance and optimize energy transfer when powerways are less than 20 miles long. Solenoid type series reactors will provide rapid voltage recovery in less than 8 milliseconds when faults occur. With these new components in place, energy flow across AC powerways will be optimized to maximize the utilization of energy production facilities. With fast acting impedance optimization, AC powerways will have 125% to 140% of the transfer capability of today’s transmission lines. Increased transfer capacity means fewer new transmission lines will need to be constructed to accommodate new renewable energy production facilities, as existing lines can be used to transmit additional energy.
Powerways will be either underground, aerial close spaced, or aerial triplex construction. They will be constructed to eliminate the possibility of igniting wildfires with design input from structural engineers, material scientists, environmental scientists, and vegetation management professionals.
Serviceways: Upgraded Distribution Lines
Serviceways will be upgraded distribution lines of today, designed to accommodate bidirectional electric vehicle chargers and distributed energy resources. Serviceways will be automated so that the status of every automatic device is monitored and actuated as needed to minimize power interruptions and eliminate the possibility that wildfires are ignited by faulted serviceways.
Figure 3 shows a typical distribution line drawing with reclosers, switches, and voltage regulators, all of which are standard use today. When distribution lines are upgraded to serviceways, shown in Figure 4, flow controllers will replace reclosers and switches, while voltage control modules will replace voltage regulators.
Flow controllers are components that enable a distribution network to function as an automated smart grid. They will have the fault current interrupting capability of reclosers plus the capability to receive segment status and react to the direction of fault current flow. Flow controllers will be located throughout the distribution systems so that no more than 250 customers lose power when a fault occurs. Communication links between electric warehouses and flow controllers will provide data to block or enable automatic closing, to shed load if overloads occur, and to reduce actuating times when the risk of wildfire ignition is elevated.
Today’s voltage regulators, which are used throughout many distribution systems to maintain voltage levels, can be damaged by reverse energy flow. This occurs when energy flows from remote locations, such as distributed renewable energy sources, to neighborhood substations. Voltage control modules will allow the unimpeded use of rooftop solar panels and other distributed energy resources. Voltage control modules are designed to maintain serviceway voltage within +/-1% of nominal voltage by injecting VARs during low voltage conditions and extracting VARs during high voltage conditions.
Serviceways, like powerways, will be either underground, aerial close spaced, or aerial triplex construction. They will be constructed to eliminate the possibility of igniting wildfires with design input from multiple subject matter experts outside the electric utility industry.
Consolidate Utilities to Move Forward
By 2050, there should be no more than ten holding companies that have acquired numerous investor-owned electric utilities. Consolidation is essential to obtain the benefits of standardization. Otherwise, electric utilities in every state will continue to prepare custom designs for every substation, every transmission line, and every distribution line.
Modern Facilities at Today’s Costs
The cost of electric warehouses will be comparable to the cost of today’s substations. This is because electric warehouses will be built using standardized components with reduced engineering costs, construction time frames, and onsite testing. Either electric warehouses or replacement substations will be needed to modernize aging substations.
The cost to retrofit an existing transmission line to a powerway will be less than the cost of building a new transmission line in parallel with existing transmission lines. Either powerways, which are retrofitted transmission lines, or new transmission lines will be necessary to accommodate increased renewable energy production. The cost to convert an existing distribution line to a serviceway will be economically feasible when the benefits of increased reliability are included in the assessment.
The challenge facing electric utilities is recognizing that customers’ perception of reliability and sustainability is just as important as the traditional focus on infrastructure costs. The opportunity for innovation is upon us.