Session: 17-05-01: Steam Turbine Generators & Auxiliaries

Paper Number: 166027

Synchronous Condensers and Their Role Supporting the Power Grid 

Synchronous condensers are critical to a stable and resilient electric power grid because they address several key challenges introduced by the shift away from traditional synchronous generators (like those in fossil fuel and nuclear plants) toward inverter-based renewable energy sources (like solar and wind). Their importance stems from their ability to provide essential grid-stabilizing physics of traditional power plants— inertia, reactive power, and system strength—without generating electricity or emissions. They’re a proven, mechanical solution to the electronic challenges of a renewable-heavy grid, ensuring stability and resilience as the energy transition accelerates.

Unlike traditional plants, most renewable sources don’t naturally produce AC power with spinning turbines. Instead, they generate direct current (DC) (e.g., solar) or variable AC (e.g., wind), which is converted to grid-compatible AC via inverters—electronic devices that lack the physical inertia of synchronous generators. This transition, combined with the retirement of large, centralized plants, raises several stability challenges including loss of inertial, intermittency and variability, reduced dispatchability, and voltage and reactive power control.

An effective solution towards maintaining the stability and resiliency of the electric power grid as it is evolving with increasing renewables combines the construction of new gas turbine generator plants having synchronous condenser operation capability with the repurposing of existing fossil and nuclear facilities into synchronous condensers while in some cases also maintaining their ability to operate in power generation mode.

 

For the part of new gas turbines generator plants, they provide power that is quickly dispatchable to balance the intermittency of renewables like solar and wind, ensuring a reliable supply during peak demand or low renewable output.   When adapted with a SSS clutch, the generator can operate independently (and efficiently) from the turbine as a synchronous condenser to provide essential grid stabilizing services of inertia and reactive power.         

 

Converting retired plants’ synchronous generators into synchronous condensers leverages their inherent inertia and reactive power capabilities to stabilize grid frequency and voltage, counteracting the loss of these services as traditional plants phase out. Together, these strategies bridge the gap between the old grid’s mechanical reliability and the new grid’s electronic complexity, enhancing resiliency in an increasingly decarbonized energy landscape.   Conversions of retired plants have the additional benefit of repurposing an existing asset and infrastructure which is very cost effective in comparison to building news synchronous condenser plants from scratch.  Conversions have added environmental benefit by avoiding unnecessary waste of demolishing and building new condenser capability and keeps the plant from being replaced with entirely new fossil infrastructure elsewhere. 

This combined solution is advancing at an increasing rate in the US and globally through both long- and short-term conversions of retired or retiring power plants and in the construction of new combustion gas turbine power plants with synchronous condenser capability.     

Presenting Author: Alan Spisak ElectroMechanical Engineering Associates, Inc. (EME)

Presenting Author Biography: Alan Spisak is the Chairman and Chief Technical Officer of ElectroMechanical Engineering Associates (EME). He has over 30 years’ experience with large rotating electric machinery in the areas of new design, equipment enhancement, trouble shooting, and failure analysis. Types of equipment include hydro, turbine and wind turbine generators; synchronous, induction and DC motors; excitation systems and other specialty equipment.

Mr. Spisak holds a Bachelor of Science in Mechanical Engineering Technology from Penn State University and is a registered PE in the state of Pennsylvania. He holds a US patent for the conversion of cross compound generator units to synchronous condensers using a single drive motor.

Authors:

Alan Spisak ElectroMechanical Engineering Associates, Inc. (EME)
Randall Attix SSS Clutch