During the year of 2007 Systems Insight provided generator control system engineering services to deliver a generator paralleling controls upgrade at Aurora Place in Sydney, New South Whales.
Scope of Works
As a subcontractor to Commercial Energy Services Pty Ltd, Systems Insight provided the following commercial services:
- Design engineering and CAD drafting.
- Control panel manufacture.
- PLC program engineering.
- SCADA PC and UPS hardware.
- SCADA software license and software engineering.
- Site cable schedules.
- Coordination of interfacing with BMS.
- Factory testing.
- Site Commissioning.
- Manuals and documentation.
Generator Paralleling Controls
The generator paralleling controls involved the implementation of custom designed and manufactured generator control panels including Woodward GCP-31 controllers. Each Woodward GCP-31 features direct CAN Bus communications to the MTU MDEC microprocessor controllers on each of the three 1850kW MTU diesel generator sets. Each of these ATS controllers monitors the voltage, frequency, and phase relationship of the generator and the common bus in the manner described below.
When the generator is called for, the controls automatically initiate the starting of the diesel engine and connection of the generators to the common bus.
The system automatically connects the “first ready” engine generator set to the common bus. Each engine generator in the multiple system attempts to attain normal voltage and frequency for the “first ready” status.
Further sets are synchronized to the bus and their respective generator circuit breaker is connected when correct voltage, frequency and synchronisation are attained.
The generator paralleling controls adjusts engine speed to share real power load within 10%, and also adjust voltage regulator setting to share reactive load within 10%.
The engine MDEC controller is configured for the correct speed droop setting for stable load sharing.
For an unplanned outage (dead bus start), each ATS operates to connect to the generator bus in a predetermined order, in an open transition, up to the limit of the available generators.
For testing or peak load lopping (mains bus powered up), each ATS will individually and sequentially parallel and synchronize the generator bus to the mains bus, following the predetermined priority from the HMI, up to the limit of available generators. The controls will ramp up and soft load the load to the generators.
When mains is again available or the test completed, the emergency power generator (EPG) controller will synchronise to mains and the mains ACB will close and the EPGs will run in parallel with mains. The return to mains for unplanned outages is automatic.
The EPG controller will soft unload (ramp) the generators, open the generator ACB on each ATS individually and sequentially according to the predetermined priority (in reverse order to loading on to generator), until all ATS are switched back to mains. Each ATS is operated sequentially, with time delays between each ATS. When there are no remaining calls for EPG and no connected loads, the generators can then go into warm down mode, then shut down.
In the event of an unplanned power outage during loading or unloading, the ATS not already connected to EPG supply is brought onto EPG supply by open transitions, following the same priority.
In the event of an unplanned power outage while the ATS is in closed transition, both circuit breakers within the ATS shall open, before reverting to the unplanned outage scenario.
Generator Master Control Panel
A new Master Control panel was designed, manufactured and installed to manage overall operation of the emergency power system, the Schneider Modicon Premium PLC platform was used for this application and was programmed using the Schneider Unity Pro software. The purpose of the Master PLC is to perform control and monitoring of generator ancillaries, including the following:
- Radiator fan / aspiration fan controls.
- Fuel pump monitoring.
- ATS co-ordination.
- Load shedding control.
- BMCS Gateway.
- CAN bus switching.
- EPG warnings and faults from the EPG controller.
- Monitor all power parameters and status from the EPG controller.
- Monitor all power parameters and status from the ATS controller.
- Communication status to all connected devices and nodes.
Load shedding is controlled by the PLC. The automatic load transfer to EPG supply is not enabled where the additional load (as measured from the ATS controller) exceeds the generator’s adjusted capacity (as calculated from the generator nameplate ratings and the maximum utilisation factor, entered on the HMI). Load shedding parameters are based on settings entered via the HMI, and stored in non-volatile memory in the PLC. These settings are not the same as the ATS switching order.
Dual Schneider Megalis XBT G HMI touch panels were installed in the generator room and main switch room to provide an extensive operator interface to the system.