Synchronous condensers: Key to grid stability in North America

This is the largest condenser project at one location in the United States and possibly the world. Siemens Energy SGen-2000P series condensers will greatly increase the amount of energy from IPP that can be delivered to project participants in Southern California. In fact, the high-voltage direct current HVDC line from Delta to Adelanto cannot run at 100 percent without these condensers.

This was the case in San Clemente, California, in 2013. For more than 40 years, the San Onofre Nuclear Generating Station produced electricity for the homes and businesses in the area. In 2013, the plant was decommissioned somewhat unexpectedly, leaving a gaping hole in the region’s power generation mix.

The California Public Utilities Commission requires a sufficient Planning Reserve Margin - excess generation on-hand to handle peak loads which is often needed in Southern California’s stifling heat. Generation from other nearby power plants helped fill the gap, but they were still short on other needs for stable grid operation like short circuit power, inertia and voltage regulation. The California Independent System Operator said that an alternative means of voltage support was necessary. The utilities and power producers turned to Siemens Energy for a solution. Seven Siemens Energy synchronous condensers now operate in the area, providing the missing grid requirements and stabilizing the network.

A synchronous condenser is essentially a motor. The shaft is not connected to a turbine and spins freely. Its purpose is to adjust conditions on the electric power transmission grid by either generating or absorbing reactive power as needed. In addition, it provides sufficient inertia and additional short circuit power. In 2024, synchronous condensers are being called upon frequently in North America, and for similar reasons – to fill needs of stable power grid transmission.

There is something else that the electrical grid needs in addition to just electrons – inertia. Often called “rotating mass” or “strong power,” large power producing entities like plants running on coal, nuclear and natural gas create inertia for the system - a steady flow of electricity that keeps the system running smoothly. As more coal-fired plants are retired throughout the country, even if they are replaced by cleaner forms of electricity, inertia is lost in those systems creating frequency oscillation. Synchronous condensers provide the necessary inertia. They require less than 15 minutes of start-up time and have the capability to quickly provide dynamic voltage support.

Synchronous condensers are part of Siemens Energy Flexible Alternating Current Transmission Systems (FACTS) suite of products - solutions for increasing the reliability of alternating current grids, ensuring stability, and boosting transmission efficiency. With these modular and customized solutions from a single source, high voltage fluctuations and power failures can be prevented, network assets can be optimally utilized, and load-induced disturbances can be mitigated.

In 2018, Public Service Company of New Mexico installed a Siemens Energy synchronous condenser at its Blackwater station in Clovis, NM to help balance the 200 MW of wind capacity being delivered along a 216-mile transmission line to the Albuquerque area. Wind generation facilities tend to be in remote locations which has presented utilities with control and operational challenges, leading to increased interest in synchronous condensers.

This is how the energy transition can look – building net-zero energy production and turning to trusted technology providers to help maintain the reliability and affordability that Americans have come to expect. As we move away from a system that was built on always-on power from nuclear and fossil fuels, synchronous condensers and other grid modernization products hold the key to grid reliability.