Understanding AGC and AVC Functions in Energy Management Systems for Advanced Energy Storage

Energy Storage Systems (ESS) have become integral to modern power grids, offering solutions like peak shaving, load leveling, and frequency regulation, which are essential for maintaining grid stability and efficiency. These systems can smooth out the variability of renewable energy sources like solar and wind, reduce electricity costs by charging during off-peak hours and discharging during peak times, and ensure uninterrupted power supply during grid outages through islanding operations.

At the core of an effective ESS is the Energy Management System (EMS), which serves as the decision-making hub for the storage station. The EMS interacts with the Battery Management System (BMS) and the Power Conversion System (PCS), collectively referred to as the “3S” system. This system is crucial for monitoring and managing the storage station, ensuring seamless integration with the grid, and providing a suite of advanced functionalities like data collection, storage, processing, visualization, and alarm management.

Two of the most critical functionalities within an EMS are Automatic Generation Control (AGC) and Automatic Voltage Control (AVC). These features play a pivotal role in maintaining the stability of both frequency and voltage within the power grid.

AGC (Automatic Generation Control)

AGC is an automated control technology designed to maintain the frequency stability of a power system. It works by continuously monitoring the grid’s frequency and adjusting the active power output of generators in response to any deviations. When the grid frequency deviates from the standard, AGC sends signals to the generators to either increase or decrease their power output, ensuring that the frequency returns to the desired range. AGC systems typically consist of a central controller and multiple generators, where the central controller is responsible for monitoring and adjusting the load of the generators.

AVC (Automatic Voltage Control)

Similar to AGC, AVC is an automatic control technology, but its focus is on maintaining voltage stability within the power grid. AVC monitors the grid’s voltage levels and adjusts the reactive power output of generators in response to voltage deviations. When the voltage strays from its set standard, AVC sends signals to the generators to adjust their reactive power output, thereby bringing the voltage back within the acceptable range. The AVC system, like AGC, is managed by a central controller that oversees and adjusts the reactive power output of multiple generators.

AGC vs. AVC: Key Differences

The primary difference between AGC and AVC lies in their control targets. AGC is focused on frequency control, while AVC is concerned with voltage control. Both parameters are crucial for the reliable operation of power systems, but frequency deviations generally have a more immediate and significant impact on the operation of electrical equipment. Therefore, frequency stabilization typically takes precedence over voltage stabilization.

In summary, the integration of AGC and AVC functions within an EMS is vital for the optimal operation of Energy Storage Systems. These automated controls ensure that both frequency and voltage within the power grid remain stable, thereby enhancing the reliability and efficiency of power supply, particularly in systems with a high penetration of renewable energy sources. As the energy landscape continues to evolve, the roles of AGC and AVC in grid management will only become more critical.

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