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Load Sequencing Panels: Host Utility Perspective

Updated: Jan 15

In the first part of this series, I presented the capabilities and benefits of load sequencing panels (LSPs) for residential consumers. To briefly recap, LSPs are a combination circuit breaker panel and a switching panel, where the flow of power is monitored by a microprocessor. LSPs replace traditional circuit breaker panels in residences, and can be controlled via app. LSPs will allow customers to track their energy so that they can monitor their electric bills in real time.

The benefits of LSPs to residential customers are clear. Now let’s explore the ways in which LSPs will benefit host electric utilities.

LSPs can assist in event mitigation and recovery during extreme weather events, like the winter storm in Texas last February, or the California heat wave that led to days of outages last summer. Once in place, LSPs will eliminate the need for conventional, host utility initiated, rotating outages when consumer demand exceeds energy supply. In addition, consumers will support host utility recovery from failures that, in the past, would lead to wide area blackouts.

Additionally, LSPs will improve the financial stability of energy producers and host utilities by reducing their investment in new infrastructure. LSPs will also prepare the grid for next generation technology, such as electric powerways, serviceways, and electric warehouses, which will ease the transition to distributed renewables as a key energy source.

Let’s take a closer look at how LSPs will support host utilities.

No More Rolling Blackouts

Rotating outages (a.k.a. rolling blackouts) are implemented by host utilities when energy demand is expected to exceed energy supply. Most days, energy is produced for less than $0.03 per KWH. During peak load periods, host utilities purchase energy at much higher costs, as much as $1.00 per KWH. When additional energy is unavailable at any price, host utilities preserve the balance by initiating rotating outages.

Host utilities use underfrequency databases to determine which distribution lines can be interrupted in anticipation of energy shortfalls. Although actual undervoltage and underfrequency events are rare, they have occurred and are a design consideration.

Presently, undervoltage and underfrequency load shedding occurs on a substation basis: voltage and frequency are monitored at substations, and an entire distribution line is interrupted when an event occurs. Using underfrequency databases to select loads for rotating outages has negative impacts on businesses, transportation systems, and the overall quality of life in areas experiencing the outage. Usually, rotating outages are preemptive, meaning they are put into place to prevent an undervoltage or underfrequency event from occurring.

Rather than monitoring at the substation, LSPs monitor grid voltage and frequency at individual residences. This way, only interruptible and preferred loads, as designated by individual residents, will experience an outage during an undervoltage or underfrequency event. LSPs will be programmed to implement load shedding from specified circuits when voltage is less than 117 volts or frequency is less than 59.2 hertz.

Of course, if additional load shedding is necessary, power to essential loads may be stopped. However, the goal of LSPs is that only interruptible and preferred loads are shut off during an undervoltage or underfrequency event. Residents should continue to have power to essential devices such as refrigerators or WiFi routers, so long as they have classified those items as essential in the LSP app.

The ability to interrupt residential loads in real time will eliminate the need for preemptive, conventional rotating outages. When monitors in LSPs actuate to shed load, businesses will be able to continue as usual, since LSPs are designed to shed load from residences only. Traffic signals will continue operating, restaurants can continue to do business, and factories will continue producing.

Consider the August 9, 2019 U.K. blackout. When a fault occurred, the Little Barford gas-fired plant (698 MW) and the Hornsea offshore windfarm (1200 MW) tripped offline within seconds of each other, which led to a wide area blackout. Had LSPs been in place, the grid would have been able to ride through the loss of these large power plants.

LSPs: Next Generation Solutions

LSPs are necessary to prepare the grid for updated electric energy generation, namely from distributed renewables. LSPs will aid in the efficient transfer of energy from distributed renewables located at individual residences. The present approach to rotating outages will exacerbate, rather than mitigate, undervoltage and underfrequency conditions, unless host utilities modify their approach to account for distributed renewables.

Prescient’s vision for the updated electric power grid, including LSPs and other next generation components, is outlined in figure 1. The figure also includes updated communication channels, which will be necessary as utilities update their billing practices and LSPs become commonplace.

As a brief overview, electric powerways will include necessary updates to existing transmission lines; electric serviceways will include similar updates to distribution lines. Electric warehouses will be updated substations that contain storage modules in addition to traditional substation components. Browse our next generation blog collection to learn more about each of these components, or contact us with questions.

ELSPs: The Next Step

Because electric load and energy sources are continually changing, LSPs can be supplemented with Enterprise Load Sequencing Panels (ELSPs) designed for general business use, including offices, factories, and more. In cities, such as Pasadena, CA, where more than 50% of peak load is air conditioning demand, supplemental load shedding will be required. This is especially important if an undervoltage or underfrequency event were to occur during lower load conditions, such as in the spring or fall. ELSPs will provide supplemental load shedding when necessary.

For example, in April, few residential consumers are using air conditioners. Should an undervoltage or underfrequency event occur at that time, residential LSPs may not be able to shed enough load to prevent a wide area blackout. However, ELSPs can shed interruptible loads from businesses at any time of year because businesses are continually demanding a set amount of power.

ELSPs will bridge energy shortfalls during light load periods. Whereas LSPs are fast acting, first line devices, ELSPs are delayed so that they are second line devices. I’ll talk more about ELSPs in a future blog post.

LSPs and ELSPs Benefit Utilities

Once LSPs and ELSPs are implemented, consumers, rather than host utilities, will have the ability to automatically reduce selected loads when predictable, rare events, like the winter storm in Texas, occur. Had they been in place, LSPs would have prevented the almost statewide power shutdown in Texas by selectively shedding load when power demand exceeded supply.

LSPs will allow host utilities to eliminate expenditures for new infrastructure, including equipment that may only be needed for a few days each year while repairs or maintenance work is underway. LSPs can also be part of the solution to climate change because they will eliminate the need to run inefficient, outdated generating equipment when the cost of power increases significantly. Instead, LSPs will simply decrease residential power demand.

Change is Ongoing

Electric utilities develop detailed models to analyze known problems. However, anticipating future needs remains a concern. In the 1960s, every electric utility assumed that the demand for electricity would increase by 7% per year, indefinitely. Then the first OPEC oil embargo occurred. In 2002, every electric utility assumed that a multi-state blackout was unlikely. Then the Northeast blackout of 2003 occurred. In January 2021, electric utilities in Texas assumed that they were ready for winter conditions. Then the winter storm arrived.

The electric power grid can be compared to the stacking game Jenga. In Jenga, each player is trying to advance without collapsing the tower. With each play, the block that is least likely to result in tower collapse is removed. Every player has a clear vision of the present state of the tower. When operating the electric power grid, the event that will result in grid collapse is much more difficult to ascertain. In the electric power industry, only a few players have a somewhat better vision of an event that could lead to total grid collapse.

The goal of LSPs is to be prepared for inevitable, rare events, so that the grid does not collapse. Instead, the grid will be supported by load shedding at specific, residential circuits, rather than from an entire distribution line. Like playing Jenga with magnetic blocks.

LSPs will benefit host utilities and consumers, and assure that essential services are not interrupted. If you’d like to learn more about LSPs, contact us to discuss the opportunities and advantages at greater lengths.

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