Diesel engine can not give more than half load 10

[ViCH]

Hi everyone. I am electrical technician, and I have problem with Emergency Diesel Generators at site. Full Power Capacity is 2.7MW, but we get speed unstable starting from 1.3 MW, if we want to give more power then engine looks like can not accelerate and frequency start to drop until under-frequency trip. We already check all fuel injection pumps, fuel pressures condition of valves, fuel filters.. Check electronic controls and all auxiliaries, but did not find any major problems.
By trending I found fuel demand is adequately changes with load requested. But I also mentioned that manifold air pressure is maintain 14.2 PSI before start, and 14 PSI +-0.3 fluctuating during and after start. Is it OK? Could it be problem with turbocharger, or wastegate control?
Engine: GE 16V228.
Turbocharger: 7S1716 compressor end. E-40811A

Viktor
Electrical Technician II

 

[ViCH]

I agree. Today my last night shift, after 2 weeks I am going to day shift, and my goal will be to get approval for load test. Anyway, I have learnt much during this troubleshooting, thanks for You all! Once any update or results, I will write here.

Viktor
Electrical Technician II

 

[ViCH]

One more question, how engine perform:

1) If AVR and Governor in Droop mode
2) If AVR no droop, and Governor Droop
3) If AVR droop, but Governor not.

Is it major changes will be?

Viktor
Electrical Technician II

 

[catserveng]

1) Both in Droop mode, as real power applied, engine speed will drop, as reactive power applied, voltage will drop

2) Governor in Droop, AVR not, as real power applied, engine speed will drop, AVR will maintain constant voltage even if reactive load applied

3) Governor in Isoch (no droop), AVR in Droop, engine speed will remain constant no matter how much load applied (within limits of engine power rating), as reactive power applied, voltage will drop

Maybe you'll find the attached helpful, also a couple links to some pages with some basic descriptions and some references to some other papers on the subject,

https://www.svri.nl/en/generator-operation-modes/

https://www.svri.nl/en/isochronous-vs-droop-control-for-generators/

MikeL.

 

[ViCH]

Thanks for links and file!
I have read it before, and now understand separate functions of droop and iso, but what is the best combo for single genset? And what is the best combo for 2 parallel gensets? Just refer to your experience. Without grid.

Viktor
Electrical Technician II

 

[ViCH]

I mean best combo for stability during dynamic loads switching ON.

Viktor
Electrical Technician II

 

[catserveng]

For stand alone operation, a single unit feeding a site load, why have any droop in either the governor or AVR? If governing dynamics are properly adjusted for the loads and capability of the engine and its installed environment, then engine response to load transients is the best it can be. On the AVR, V/Hz (UFRO to some folks) setting is way more important than droop, also dynamic response, again tuned to how the generator excitation and AVR actually respond to the site loads. For many years bulk of my service calls for transient response problems were gensets that still had factory default dynamic settings for both the governor and the AVR. Having an understanding as to what the site loads are actually composed of and how they respond to outage events will dictate how the testing and tuning really need to be done. Problem is most standalone units get dropped on a site, might get a load bank test at some specified load steps and called good if it starts and gets up to speed within the time asked for.

For parallel operation, either island mode plants or paralleling to grid, in my career the predominant method is a combined active real and reactive power sharing control system, such as a Woodward MSLC (if utility paralleling) and/or DSLC's. Also other manufacturer system from Basler, Dief and ComAp or specialized systems for specific applications like Ross Hill controls on drill rigs. Early in my career isochronous kW load share control and either droop or cross current compensation for reactive power sharing was common. I try to move customers away from those system these days if I can mainly due to servicing issues long term, especially if they are still using analog AVR's.

As to your last questions, well there is a whole lot of "that depends" in my response, Usually takes a lot of questions as to what you have and how you operate it. What kinds of loads? Like are you supporting an industrial facility with large motors and a lot of smaller support loads? Maybe a rock and gravel operation with crushers and conveyors. Want a really fun system, how about a multi drill table drill ship with dynamic positioning and a ballast load trim system working in heavy seas? And my experience is all based on mostly RICE prime movers with a turbine unit or two thrown in the mix now and then from 500kW up to about 10MW in size mostly with salient pole synchronous generators. Someone with mostly smaller or larger size experience may have a different set of opinions and experiences.

Hope that helps, MikeL

 

[ViCH]

Well, genset is discussed one, and loads - a lot of 400V UPS, motors, any domestics.. Plus 11KV 250KW air compressor motors. We need at least 2 unit running. Due to our frequency dropping too high, usually when we start second big motor, we getting underfrequency trip. So our practice now, we start one compressor, offload it, then start second, load first, and then only we start to energise LV loads.
If we will make governor running in ISO, could it help?

Viktor
Electrical Technician II

 

[TugboatEng]

No, governing in isochronous should not help. Properly configured, speed droop governors should run at 51.5 to 52.5 hz at zero load and not drop below 50 hz at 100% load. The frequency should never be low enough to cause a trip in either case. Isochronous governors operate the same as droop governors during a load change but have a compensation circuit to return the frequency to nominal after the load change.

When running two units in parallel it's typically to run one in isochronous and one in droop mode. The droop engine will run at constant load and the isochronous will take any load changes. This prevents the units from competing for the load.

 

[ViCH]

That governor 723plus has jumper on terminals 9-10. This terminals is for LOAD SHARING SIGNAL. I have checked many manuals of Woodward 723+, but didnt found purpose of jumper. If i do not need load sharing, should it be jumped or remained open?

Viktor
Electrical Technician II

 

[catserveng]

For 723 governors with load sharing, if not used a jumper is installed, jumper should have been there from the beginning.

MikeL.