Synchronous condensers: Key to grid stability in North America

The Intermountain Power Project (IPP), transitioning from coal to natural gas and renewables, will also highlight the crucial role of Siemens Energy synchronous condensers in integrating renewable energy sources and enhancing grid stability across North America.

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 with a shaft that spins freely, not connected to a turbine. Its purpose? To balance grid conditions by providing or absorbing reactive power, adding inertia, and increasing short circuit power. In 2024 and beyond, North America increasingly relies on these machines to stabilize the power grid as renewable integration rises.

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. This has led to rising demands globally over the past years.

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 the face of energy transition—collaborating with trusted partners to ensure Americans receive reliable, affordable electricity while decarbonizing the grid. Synchronous condensers and other Siemens Energy technologies are at the center of this progress.