DSLC from Woodward Not Operate in Droop?


Thread Starter


Hello all,

We have a system with 3 Gas turbines solar and 2 Steam turbines. DSLC from woodward is used to make the control of it, where, All is running on Isoch mode and DSLC making control of the load sharing.

Since we are having problems on this configuration, we asked our PMS manufacturer to put all on droop, but came with the answer that is not possible for this DSLC to operate in droop...

Is there any reason for that ?
This is the part number of the DSLC 9905795.

Appreciate your ideas,

I can't tell from the manuals available for download from the Woodward site exactly which DSLC you have, and, as usual with Woodward manuals they are ambiguous. One area of the manual for the DSLC-2 says it can operate in droop or isochronous control, and then a few bullet points later it says that when operating multiple generator-sets it operates in isochronous speed control.

By the way, anyone can register and download manuals from the Woodward website, all that's required is an email address--and I've never received spam from them or felt that they sold my email address to anyone to send unsolicited email adverts.

Woodward also has an email support (www.turbinehelpdesk.com, I believe) and a phone number--though the last two times I've called (in the last two months) I've not gotten a call-back or an answer to my emails.... This outage season has been CRAZY, and that might be the reason; but, their response has usually been better in the past.

I would normally refer you to the manuals, but I couldn't find any definitive answer in either the product specification or the manual <b><i>for the DSLC-2</b></i>. Again, it's not clear to me which model you have.

I do know that tuning DSLCs can be a trial and error method, and that changes to governor configurations can have an effect on past tuning--negative effect. It's not exactly clear what the circumstances are at your site or how long this problem has been existing, but it just might be that a tune-up is in order.

Hope this helps!
Terminal 47 is the CB AUX contact. If you open, or have no connection, to the terminal the DSLC will operate in droop.

Thank you, mine is not the DSLC 2, is simple DSLC i suppose its like one family before.

The point is that it was working fine, all machines on isoch. then when putting on manual, it was crazy. also changing to manual in droop, went crazy. And somebody got the information in the past from vendor that was not supposed to run on droop.
Hi Eguy,

thanks. Sorry if stupid question but i've been in touch with pms for a short time, this forum have helped a lot actually :).

>Terminal 47 is the CB AUX contact. If you open, or have no
>connection, to the terminal the DSLC will operate in droop.

So basically all machines running on isoch, and when we put to manual and select on the generator to droop, it all go crazy.

So i have to check this auxiliary contact everytime i want to put a machine on droop? i change on the generator panel and check this 47 right?

Is your power plant operating as an island (independent of a larger grid), or is the power plant synchronized to a grid with other generators and their prime movers?

Is the problem that the system is unstable when it separates from a grid and is running some plant or process independently of the grid?

Is the PMS trying to control frequency for an islanded power plant, or is it trying to control the amount of power being exported (or not) to a grid?

How long have you been having problems with this configuration you describe? Since the DSLC is an early version, I presume things were running fine for some time, but now something has changed and it's no longer working as before. Please confirm and clarify.

And, what kind of problems are you experiencing that is prompting this query? Please be as specific as possible.

PMSs can be configured to do all manner of things, or just one thing--it all depends on what the original specification was designed to provide. Many times the design documents are included with the plant operation and maintenance manuals and can provide a great deal of insight into how the system was designed to operate. It's very common for there to have been a change of management/ownership in a plant and for the management/ownership to have unrealistic perceptions of what the plant is capable of, in this case perhaps the PMS?

And if you're new to PMSs, it's probably very helpful to find and review the design documents provided with the equipment as often they provide a lot of useful information. As for the DSLC, Woodward equipment can be used for MANY different purposes and applications, and their manuals reflect the many configuration possibilities without providing many sample configurations, or the ones provided don't match the one you're working with. It can really take a few readings and much consideration to understand the capabilties and whittle them all down to the one being implemented at your site.

Anyway, if you will take a few moments and answer each of the questions above we may be able to provide a more concise and helpful response.

I might also suggest downloading a copy of Woodward Manual 26260, 'Governing Fundamentals and Power Management.'

There is some good information in there, some typographical errors, and some unqualified statements (especially in the "Droop" section). But I think you will find the section on 'Load Sensing, Load Sharing, Base Loading' informative and helpful.
I guess I don't understand what you mean it goes crazy. Can you explain that a little better. When you put a generator controller into droop with other Isochronous units, then it will probably unload that generator down to a low level.
When a governor is switched from Isoch to Droop, there is usually logic to capture the current operating condition (load; Droop speed reference (which is often calculated even when running on Isoch--for tracking and transfer purposes)) and keeps the load stable once on Droop control mode. If not, the governor is not very sophisticated and the operator had better be aware of the situation and take appropriate action.

Once on Droop, the load won't change unless:

1) The prime mover speed/load reference changes,


2) The frequency changes--and whatever is controlling the Isoch machines should be controlling them to keep frequency constant. If the load changes during or after the governor is switched to Droop, the load on the Droop machine should remain constant (presuming the speed/load reference is stable) and the Isoch units should adjust their output to maintain frequency--or whatever is controlling the Isoch units should adjust their outputs to maintain frequency.

The Droop unit load should not change just simply because the operator switch the governor from Isoch to Droop. Unless the governor programming and configuration is sorely lacking.

In any case, you're still correct--the original poster has not provided enough information about "going crazy".

Hopefully he will!
The original DSLC did not have the droop tracking feature, as it came out in 1992. The newer DSLC-2 does have that feature.