As distributed renewable energy sources expand and electrification of homes and businesses increases, additional energy will be required from the electric power grid. This is especially true when severe weather conditions occur, including heat waves, cold snaps, and extreme storms, all linked to climate change. As electric utilities move toward the fourth generation (4Ge) electric power grid, they will need to update their demand response model when electric energy demand exceeds supply and load shedding is required.
Electric utilities' goal will remain the same: provide reliable electric energy to every customer. However, the parameters, including peak load timing and energy costs, will change.
Instead of building expensive, high capacity facilities to provide extra electric energy for the 4Ge grid, and passing along increased costs to consumers, electric utilities should encourage customers to install load sequencing panels, a new technology that selectively reduces consumer demand.
Load sequencing panels (LSPs) will reduce the number and capacity of excess facilities that need to be built. In addition, using LSPs to selectively reduce customer load will benefit utilities by optimizing operating costs and expenditures for new equipment, preparing the grid for severe weather, and improving relationships with consumers.
Redundant, Not Reliable
Many of the facilities that are interconnected to form the electric power grid of today are rarely used to their full capacity. This is because historic grid designs require redundancy to ensure reliable power. For example, redundant substation transformers are installed so that all customers can continue to be served even if one transformer is out of service. Also, power generating facilities are often built to produce far more power than is regularly needed in case another generating facility trips offline.
Though these seem like logical solutions, high cost components and power production facilities are only used during a few peak load days every year. Additionally, even with extra infrastructure in place, electric utilities still need to reduce load when energy shortfalls occur.
Despite expensive, redundant infrastructure designed to ensure grid reliability, the grid is not always as reliable as it should be when high demand or severe weather increases load.
Consequences of Outdated Load Shedding
Presently, electric utilities use two forms of load shedding, depending on the conditions:
Rolling blackouts when energy shortfalls are predictable.
Underfrequency load shedding when sudden, unexpected energy shortfalls occur.
Rolling blackouts and underfrequency load shedding are brute force solutions with economic and political consequences. After the Fukushima earthquake and subsequent nuclear disaster in March 2011, rolling blackouts initiated to reduce load roiled Japan’s economy. During the cold snap in Texas in February 2021, reactive rolling blackouts led to numerous deaths and had widespread economic, environmental, and political consequences.
Consider an electric utility that owns and operates 100 distribution lines. When an energy shortfall occurs, underfrequency load shedding schemes will reduce load by opening circuit breakers on 10 lines at a time as frequency decays. However, not every line is subject to load shedding. Distribution lines that serve critical loads, such as hospitals, police stations, or sewage and water treatment plants are exempt from load shedding. Industrial customers that pay for premium service are also exempt from underfrequency load shedding.
When all exemptions are considered, this electric utility may exempt 40 of their 100 distribution lines from their underfrequency load shedding scheme. The remaining 60 non-exempt distribution lines will be included in rolling blackouts to reduce predictable energy shortages. When unexpected energy shortfalls occur, 30 non-exempt distribution lines will be included in underfrequency load shedding.
When the expected load is 8 MW per distribution line and the predicted energy shortfall is 40 MW, circuit breakers powering 5 distribution lines will be opened every 15 minutes on a rotating basis. During these rolling blackouts, customers powered via non-exempt distribution lines will experience a 15-minute power outage every three hours. For these businesses, several 15-minute outages a day will result in lost time, revenue, perishable items, and more. When underfrequency load shedding occurs, longer outages, up to 24 hours, could be expected.
Load Sequencing Panels: 4Ge Demand Control
Rather than shed load through the methods listed above, electric utilities should invest in modern load sequencing technology for next generation demand control. They should provide incentives for customers to install load sequencing panels that will reduce load when peak load exceeds the capability of energy sources, when voltage drops below scheduled values, and even when the cost of energy is very high.
Installing load sequencing panels, as illustrated in Figure 1, would negate the need for underfrequency load shedding schemes and eliminate price spikes when energy production shortages occur. By outfitting LSPs with Bluetooth controls that can automatically curtail load in an individual building, utilities can provide demand response in a timely manner and consumers can use less energy when the cost per kilowatt hour is above a set threshold.
Figure 1 shows the flow of electric energy, or “power flow,” and communication between an energy producer, electric utility, and load sequencing panel. Here, the LSP is located on the circuit breaker of a home.
Each consumer would use their LSP app to select some, but not all, circuits to be turned off when particular conditions occur. Consumers may choose to turn off some circuits due to high cost of energy, such over $0.25 per KWH. Electric utilities may also select criteria, such as when voltage drops to 118 volts or frequency decays to less than 59.9 Hertz.
Consider an all-electric home with the loads outlined in Table 1. In the table, enabled means the connected circuit breaker will remain closed, and the electrical load can always access power. Sequenced means the connected circuit breaker will be automatically opened during adverse grid conditions; load will continue until the associated appliance/electronic cycle completes, but cannot be turned on until the conditions have resolved. This could be when the cost per KWH has lowered below the threshold, or a system upset has been resolved.
By establishing set rules within the app that link to these conditions, LSPs will automatically reduce load by stopping the flow of electric energy to pre-set circuits. This ensures that consumers never lose power to their essential devices, while non-essential circuits may lose power to shed load. Smart appliances can interface with LSPs to supplement load reduction. On peak load days during the height of summer, LSPs can eliminate the need for rolling blackouts to address energy shortfalls.
Improved Demand Response is Essential
Load sequencing panels provide many benefits to electric utilities and electricity consumers alike. The technology required to implement LSPs is available today. Now is the time for electric utilities to embrace new technologies so that they are prepared for the expansion of distributed renewable energy sources, and other changes that will occur as the 4Ge electric power grid expands.