Always ready for a challenge, the AJ Power engineering team excels once more in a challenge to provide a generator large enough to start a 3.2MW, 10kV motor direct online (DOL). This in turn is the starter of a 64MVA, 105kV gas turbine.
The electric motor, once running, would connect to the turbine gearbox via a Voith torque converter to run it up to firing speed. It sounded straight forward enough until the additional requirements were mentioned. The load of 3MW would be presented in approximately 1 second to the starter motor and in turn the generating sets.
Onerous specified electrical characteristics were also required to protect the motor. 3 nos. conventional synchronised generating sets with oversized alternators to limit voltage and frequency dips would have satisfied the requirement but they were well outside the clients budgetary constraints.
Joe Bradley, our Director of Sales, a chartered electrical engineer with power plant and network knowledge spanning nearly 40 years, took up the challenge of finding a solution that would meet the clients needs. He brought together our team of highly qualified senior electrical and mechanical engineers to find a novel method of starting. This resulted in selecting 2 generating sets instead of 3, with a special synchronising system that resulted in a 30% plus cost saving to the client but more importantly, coming inside their budgetary requirements. Numerous technical meetings took place with the utility engineers and our distribution partners before it was accepted that the theory could be put into practice.
The onus was on AJ Power to deliver the solution. The machines were assembled in our Craigavon UK factory and, where possible, the site conditions were simulated using both reactive and resistive load with numerous performance traces taken. The results were in line with calculations and the machines were then fitted into acoustic enclosures for delivery to site. In December after extensive commissioning, the project was handed over to an appreciative end user.
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