Updated: Apr 20, 2021
Traditionally, energy has been created in centralized generating stations, such as coal burning power plants. As the grid transitions to renewable energy sources, these centralized energy hubs are being replaced with distributed renewable energy sources found throughout the grid, such as solar panels on home rooftops, which require levelized voltage control. Let’s explore that further.
Energy supplied by solar panels is inherently variable based on time of day and cloud cover. On a sunny day, solar panels are contributing energy to the power grid, which causes an increase in voltage. If a cloud passes over the solar panels, a sudden drop in voltage will occur. This results in a power quality issue; for example, lights dim when voltage drops. For power to be distributed with consistent quality, it must be levelized, not varied. Until the grid can handle these drops, it’s not ready to fully adopt renewable energy.
To make the grid renewable-ready, innovative voltage control modules need to be added to the grid so that distributed energy is levelized. Specifically, modules that can prevent power fluctuation by stabilizing the voltage with a 16 millisecond recovery time, regardless of customer load. This is a technology that Prescient is currently developing, and will be a reality soon.
Let’s explore Prescient’s voltage control modules in more depth. We’ll take a deeper look at why they’re needed, as well as how they work. This post gets a bit technical, so feel free to contact us if you have any questions.
The Challenge of Levelized Voltage
Maintaining levelized voltage within the traditional energy system is complicated because customer load varies hourly and seasonally. Figure 1 shows a typical distribution line load at various times of day, throughout the four seasons, with energy produced by traditional energy sources. In this example, loads peak in the summer, while other seasonal loads are less. Maintaining levelized loads is most challenging in the summer, especially in the late afternoon and evening.
When residential customers add rooftop solar panels, maintaining levelized voltage is further complicated. Power sales will be lower. Peak distribution system loads will occur after sunset and before sunrise, as illustrated in Figure 2. On cloudy days, the load profile in Figure 2 may revert to the load profile shown in Figure 1 as power produced by rooftop solar panels is reduced. This increase in variables is a significant change to the power grid.
One key to establishing levelized voltage is to control power factor at many points across the power grid. Power factor is the ratio of real power (KW) to apparent power (KVA). When KW equals KVA, power factor = 1.00, and voltage variations are minimized. When KW is less than KVA, power factor is less than 1.00, and voltage variations increase. If uncorrected, distribution line voltage will be higher during light load conditions and lower during peak load conditions. These inconsistencies lead to less optimal power transfer capability.
The Solution: Voltage Control Modules
To establish levelized distribution system voltage, voltage control modules must be implemented within the power grid. These modules are an assembly of commercially available components operated by an innovative controller. They will regulate power factor all day, every day, regardless of customer load.
Individual modules will be three-phase units rated at 1200 KVA, 2400 KVA and 3600 KVA. Fifteen KV modules, which can be applied on 12.47 KV, 13.8 KV and 14.4 KV systems, will replace step voltage regulators, fixed capacitors, and switched capacitors.
When power factor is less than 1.00 due to the capacitance in power cables, voltage control modules will switch inductors into service to increase power factor and optimize distribution system voltage.
When power factor is less than 1.00 due to the inductance of power cables, transformers, and motors, voltage control modules will switch capacitors into service to increase power factor and optimize distribution system voltage.
In cities where distribution lines are less than 2 miles long, voltage control modules will be placed in electric warehouses (next generation substations, to be discussed in a future post). In rural areas, voltage control modules will be placed along distribution lines, at 3 – 5 mile increments.
Advantages of Voltage Control Modules
The advantage of voltage control modules is that estimated load amps and power factor, rather than actual time-varying values, can be used to locate modules. Algorithms in microprocessor-based controllers with innovative DIP (differential, integrated, predict) logic will switch capacitors and inductors on and off to maintain steady state, levelized voltage between 100.5% and 99.5% of nominal at the meter base at all locations along a distribution line.
When customer load is low and renewable energy production is high, voltage control modules will act to reduce voltage. When customer load is high and renewable energy production is low, voltage control modules will act to increase voltage.
Learn More About Our Voltage Control Modules
The most exciting aspect of these modules is that all the components that are needed to assemble the modules are readily available commercially. This is why Prescient is already in the process of building a test module.
If voltage controls modules are something you’re interested in implementing or just learning more about, contact us. We’d love to discuss the technology at greater lengths with interested parties (and we can only dig so deep in a blog).
Remember, sustainable energy is the future. And the faster we can get there, the better off we’ll be.