Synchronous condensers design and conversion

Problem: A power company needed to control system voltage at the delivery point of a 63 MW wind farm. 

Solution: One Eaton synchronous condensers was used to provide voltage stability and fault current capacity during peak load conditions and transmission events, with Eaton's engineering services team building around a TEWAC +27.5/–14 Mvar synchronous machine. 

Results: The system relies on a variable speed drive and 1000 hp pony motor to provide trouble-free starting and synchronization, while the control system operates the condenser to control the bus voltage at the 115V substation. Integrating switched capacitor banks into the scheme, the control system continuously biases the machine output to operate in an under-excited state, allowing for full dynamic response to system faults and contingency events. 

Problem: The reactive capabilities of the transmission system would be adversely impacted by the utility’s decision to retire the generating assets. 

Solution: Eaton engineers converted three 165 MW steam turbine generators to synchronous condensers by disconnecting the turbine, replacing the excitation and control systems, and performing modifications to auxiliary systems. A PLC-based control system was implemented to handle machine startup, synchronizing and dispatch functions. 

Results: The control system ensures all machines work together to support the 138 kV bus voltage while sharing load equally among machines. 

Problem: A utility company desired system reliability and voltage stability for overloaded transmission lines and frequent voltage excursions at its facility. 

Solution: Two water-cooled, 16 Mvar synchronous condensers using variable speed drives and 500 hp pony motors were implemented to support AC voltage during peak loading conditions and transmission system outages, as well as provide fault current capacity.  

Results: The Eaton synchronous condensers solution stabilized the system by supplying voltage control and short-circuit current strength, avoiding the need for more costly transmission system upgrades.