ABB ENMC PMS - Grid connect Mode(MW Import only, Zero Export)

Hi All,

I'm working on a study of a brownfield PowerStation that supplies a Plant Load and wants to connect to a utility Grid. Details as per below:

1. Import of MW from the grid only, zero MW export
2. Existing PMS(Power Management System) is ABB ENMC 800xA based
3. 4x GE Frame6 Gas Turbines, MarkVI Controller
4. At present, they operate as an island (Droop mode - ENMC as the secondary controller)

My question is:
1. What is the preferred operating mode/operating strategy for the Gas turbines(MW? Droop? or combination of both?) during grid connected mode? It's a fact that once the grid breaker is closed, it's the grid which controls the frequency.
 
Hello Izer,
Since your plant is in Island mode, best operation mode for GTG's will be Auto mode (P-Control/Q-control). This will help to maintain the bus frequency and voltage to a pre-fixed setpoint. Also the GTG will share its load automatically according to its capability curve.
 
Hello Izer,
Best operation mode for GTG's will be ENMCS Auto mode (P-Control/Q-control). At GTG side, mode will be Droop. In this mode ENMCS will share GTG load automatically according to its capability curve. Also in Island mode Auto mode will help to maintain the bus frequency and voltage to a pre-fixed setpoint. In grid connected mode, ENMCS Auto will help to control the grid flow. For Active power, in your case you can give a import setpoint and ENMCS will maintain grid flow to that setpoint (with in deadband) with the help of GTG's which are in Auto mode. For reactive power, ENMCS have two mode ( Q-Auto and Power factor mode). In Q-Auto mode, ENMCS will control Grid reactive power flow. And in Power factor mode, ENMCS will control plant power factor.
 
Hi Joseph,

Thank you for your insights. This is really helpful. Looks like you really know well the ABB ENMCS system, I have read somewhere, ENMCS has grid capability function in its library and ready to use?

To summarise the operating modes:

Island Mode- GTG's in ENMCS Auto mode (P-Control/Q-control). At GTG side, mode will be Droop. In this mode ENMCS will share GTG load automatically according to its capability curve. Also in Island mode Auto mode will help to maintain the bus frequency and voltage to a pre-fixed setpoint.

I can confirm above is correct and this is the present setup- ENMCS PQ control(GTGs in droop mode)

Grid Mode-
1. GTGs in ENMCS Auto mode(PQ Control)- does this mean same mode as Island? At GTG side, mode will be Droop
2. ENMCS Grid MW import Setpoint

Thanks,
Izer
 
Hello IZER,
In grid connected mode, instead of Freq/Voltage setpoint, you will get option to enter Grid flow setpoint, where u can enter either import or export setpoint. For this control to work there should be GTG's in P-Control and Q-control mode (ENMCS Auto mode) for ENMCS to adjust for maintaining grid flow. At this point GTG's will be in droop mode from MarkVI
 
Hi Joseph,

You definitely have answered my question. This is really a good forum. This is my first encounter interfacing with ABB ENMCS.
Now it's crystal clear. Thanks
 
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