Managing Heavy Demand: Why and How Voltage Reduction is Used by Electric Power Companies

Electric power companies play a crucial role in maintaining the stability and reliability of the electrical grid. One of the key strategies they employ during times of heavy demand is voltage reduction. This technique helps to manage the load on the electrical system, prevent overload, and ensure that the grid remains stable. In this article, we will explore the reasons behind voltage reduction and specific methods implemented by electric power companies, using real-world examples from a utility in Florida.

The Importance of Voltage Reduction

Prevent Overloading: During peak demand periods, the electrical system can experience high loads that may exceed the capacity of transmission lines and transformers. Reducing voltage helps to decrease the overall demand on the system, preventing it from being overloaded.

Voltage Regulation: Maintaining a stable voltage level is critical for the proper functioning of electrical equipment. Reducing voltage helps to keep it within acceptable limits, preventing damage to infrastructure and appliances.

Demand Response: By lowering voltage, utilities can incentivize consumers to reduce their energy usage. This is often part of demand response programs where customers are encouraged to decrease their consumption during peak times.

Grid Stability: Voltage reduction can help maintain the balance between supply and demand. If demand exceeds supply, reducing voltage can help prevent grid instability or blackouts.

Efficiency: Lowering voltage can improve the efficiency of power distribution by reducing losses in the transmission system, which can occur at higher voltages.

How Voltage Reduction Can Save the Day

My experience as a utility worker in the largest electric utility in Florida provides insight into the practical implementation of voltage reduction.

The summer load peak is typically from 3:30 to 6:00 pm, during which South Florida experiences an 8-month hot season. Years ago, the generation capacity was insufficient to handle the increasing load, especially during extremely high temperatures.

To avoid blackouts, we implemented several measures, including:

Starting Emergency Combustion Turbine Generators: We would start emergency combustion turbines that can generate 50 Mw each when needed. Load Management Control: We introduced a load management control system that could automatically turn off AC and pool pumps for 10-minute intervals, grouped by location. Voltage Reduction: The public service commission allowed for a 2.5–3% voltage reduction. This method could reduce 20–30 Mw and provide another half-hour of support before it became less effective. Understanding the daily load curve is key to determining when these reductions are most effective.

These methods collectively helped to manage the demand and prevent blackouts, especially during summer months when the load was at its highest.

Winter peak load in South Florida is typically only experienced for 2 or 3 days a year. During these days, voltage reduction still works effectively, as heating systems in homes are primarily electrical. By disconnecting the compressor and using the fan to push air through a resistance, we could further manage the load, ensuring grid stability.

Understanding the load curve and implementing these strategies have been instrumental in effectively managing demand and preventing outages in Florida. Voltage reduction, coupled with other methods, is a powerful tool that electric power companies use to maintain the reliability and stability of the grid.

By adopting such strategies, electric power companies can ensure that the electrical grid remains stable during times of heavy demand, thus protecting homes, businesses, and critical infrastructure from power disruptions.