ABB UNITROL®6000 excitation systems

ABB UNITROL®6000 excitation systems

DESCRIPTION

ABB UNITROL® excitation systems are a key component in many power  generating units used by plant owners and operators to achieve  reliability of operations, stability, and fast transient response of their  assets, as per grid requirements.

The UNITROL® 6000 excitation systems series is  specifically designed to serve a wide range of  applications:

• Generators: steam, gas, nuclear and hydro power  plants, nuclear emergency diesel 

• Motors: steel mills, pulp and paper, chemical,  natural gas production plants, refineries

UNITROL® 6000 for indirect and static excitation  systems comes in the following versions:

• UNITROL® 6000 Medium 

• UNITROL® 6000 X-power

Selected applications

• Hydro power plant 

• Pumped storage power plant 

• Combined cycle power plant 

• Critical Steam power plant with brushless  excitation, Ifn 200 A, 400 Hz supply

Engineered solutions: 

• Online supply transfer 

• Electric braking

Selected applications

• Nuclear power plant, field current Ifn >10,000 A 

• Underground hydro power plant, Ifn 4,500 A, with  redundant air-to-water heat exchanger system 

• Gas turbine power plant, MEGATROL package with  Ifn 6,000 A and static frequency converter 15 MW  for turbine starting 

• Coal-fired power plant, Ifn 3,500 A, power part in  IP54 container, detached AVR cabinet with >150 m  distance apart 

• Hydro power plant, Ifn 4,000 A, two DC field  circuit breakers, one for DC backup excitation

Closed-loop control

• Voltage regulator with PID filter (AUTO mode) 

• Field current regulator with PI filter (MAN mode) 

• Reactive and/or active current droop compensation 

• Limiter circuits to ensure that the generator  operates within safe limits: - Maximum and minimum field current - Maximum stator current, dependent on machine  cooling media temperature - P/Q under-excitation - Volt/Hertz 

• Manual restrict to keep the generator within safe  limits, even though controlled in manual mode 

• Power factor/reactive load control 

• Power system stabilizer

Protection and monitoring functions 

• Monitoring and protection functions can be freely  configured on three action levels: 

- Alarm signal only 

- Changeover to redundant circuits 

- Instantaneous excitation trip to protect the  assets

Major available functions 

• Overcurrent protection (instantaneous/inverse  time) 

• Volt/Hertz protection 

• Loss of field protection 

• Rotor temperature 

• Thyristor conduction monitoring 

• Actual value monitoring

Power system stabilizer (PSS)

The PSS function improves the stability of the  generator and the transmission system by using  the excitation to damp power oscillations.

PSS types optionally available for UNITROL® 6000: 

• PSS 2A/2B/2C in accordance with IEEE standard  421.5-2016 

• PSS 4B/4C in accordance with IEEE standard  421.5-2016 

• Adaptive PSS (APSS) developed by ABB  Switzerland, which optimizes the PSS settings  based on the current network conditions, to  maximize availability and avoid trips due  to insufficient damping in weak networks

Main features (UNL14300)

• AC supply voltage up to 1,500 V 

• High insulation test voltages up to 7.5 kV 

• Low noise level of cooling fans ≤70 dB(A) 

• Active current balance control 

• Optional: - Redundant fans, replaceable during operation 

- “Draw-out” design for safe online repair and  function tests