Windy boy help /information

[jotec]

I have almost decided on a WB 2500 for the CHP system but have some questions. (lack of GTI understanding on my part.)

I can run the PMA at any reasonable DC voltage and the Lister will maintain that voltage, to a point, regardless of load.
I want to run it at 1800w output to mains. I know I  change the power curve but what exactly does the power curve settings do?
If I run at 300V DC (Lister is happiest at this with present gearing) can I set the power in the WB to 1800w at 300V  so l it will then output that power?
Also can I set all voltages above 300V to be 1800w so the GTI never runs high output? (maximum voltage will be below the GTI limit)

Alternatively will I have to set the output by the input DC voltage?

(The reason for 1800w is that it is the most efficient regarding exporting to grid, out elec usage, our heat requirements  and fuel efficiency. Also I don't want the GTI running at full power continually)


Thanks for any input
Dick

[Alan]

Hello Dick


Quote “ If I run at 300V DC (Lister is happiest at this with present gearing) can I set the power in the WB to 1800w at 300V  so it will then output that power? “

Yes. If you will be allowed access to the wind curve software. ?

Quote “ Also can I set all voltages above 300V DC to be 1800w so the GTI never runs high output? “

Yes. If you will be allowed access to the wind curve software. ?

Quote “ (maximum voltage will be below the GTI limit) “

What is the maximum voltage that the Lister could give.  Needs to be considerably less than 550V.D.C. To be in with a chance of the inverter working for long.

Regards

Alan

[A.L.]

hello jotec,

I believe the WB 2500 can do what you want by setting the power curve, but there may be another way, it has a little known constant voltage mode, search the user manual for 'UKonst'. It is on page 62 of the version I have. You set the target voltage and the windy boy adjusts its power 'draw' to maintain that voltage.

[Alan]

Quote “ You set the target voltage and the windy boy adjusts its power 'draw' to maintain that voltage. “

Dick wants to export 1800 W.

With that target voltage set the exported power would vary depending on available input power and mechanical speed regulation control. The engine regulator could continuously cycle to try to compensate.

Regards

Alan

[jotec]

Alan
Thanks, I think you have confirmed my (basic) understanding of the power curve concept.

I am assuming that the curve software is the download from SMA aka the 'windy boy setup tool' and I access the inverter with a PC data lead or is this not the case?

The maximum voltage on 'run away' i.e Lister governor fail is 500V at present. I thought the wb2500 can go to 600V DC or is this not the case? The Lister is presently governed to 300V +- about 30V.


A.L
Thanks for that I will have a look but the voltage is not important, it is the output I want to try and maintain at a reasonably constant  1800w rather than the maximum the WB can output for a given voltage.  If the WB tries to load the Lister to reduce the speed and hence voltage  do not think it will be able to slow it  appreciably or have I miss understood?

Dick

[Alan]

Quote “ can go to 600V DC or is this not the case? “

With : Input voltage MPP range VDc 246 – 600 Volts D.C.

With capacitors rated at 600 volts the design is some what lacking.

Windy Boy Operating instructions Version 1.0

Page 35 : Has UDC wind max voltage default at 550 Volts D.C. 
Page 36 : Only change the operating parameters when you know what you are doing !
Page 52 : Input voltage MPP range VDc 246 – 600 Volts D.C.

Regards

Alan

[jotec]

Alan
Thanks again - am I right in understanding the max set by default is 550 V DC? If I accidental went over this, but less than 600v, what would the consequences be?
Can you please enlighten me on the terms  i.e UDC MPP Upv and others in the setup tool.

With capacitors rated at 600 volts the design is some what lacking - what capacitors -am I missing something?.

Sorry to be a bit (lot?) thick but I am new to this.

Dick

[Alan]

The capacitors inside the Windy Boy that store the D.C. Energy are rated at 600 volts D.C.

A well designed system using capacitors rated at 600 volts would have a maximum D.C. Input voltage of 450 volts. This would allow the inverter to have a long and happy life.

 Page 52 : Input voltage MPP range VDc 246 – 600 Volts D.C.

No attempt to moderately rate the inverter has been made. There are also other design issues.

Regards

Alan

[A.L.]

hi again,

if you arrange for the maximum output of the engine to correspond with the output of the PMA being 1800w and program the WB with the voltage produced at the governed RPM will it not attempt to maintain its power output at the maximum available (1800w) consistent with the required voltage?

[jotec]

Alan
From your comments I assume you would recommend a maximum DC voltage of 450V. I will take this into account as it is not difficult to implement in my system.

A.L.
That is the idea but I am not sure if the WB will be happy if I set all the nodes at 1800W so it is a straight line. Will it like starting at 1800w rather than slowly building up or can I set the 'wind ramp' value so it comes up at say 100w per second once it is over minimum start voltage (udc wind start?)

Lots to understand yet but it is getting a bit clearer.

Dick


 

[A.L.]

hi,

In constant voltage mode you do not have to enter a power-voltage curve, the WB draws only such power as keeps the voltage constant.

At start-up the WB monitors the grid for a period of time, during this time it will draw no power and I assume the lister will tick-over at its governed rpm. If the grid is O.K. the WB will start to draw a small amount of power and them ramp up to 1800w while keeping the programmed voltage.

There are a number of technical fixes to your overvoltage problem, SMA themselves produce, for a ridiculous price, an overvoltage protection box. Hugh Piggott has a circuit schematic on his scoraigwind.com site. Finally there is a possible, reasonably priced product on an American site www.speakerfactory.net/PM-ALT.htm I cannot authoritatively comment on its suitability but perhaps Alan can 

[jotec]

Thanks for that A.L,
I can see how it will maintain a set voltage but how can I ensure that it is giving 1800w  at that voltage, I assumed that is where the power curve comes in or is it that the WB has a output  that is dependant on the input voltage? I assumed that the output would be determined by the input current available?

Can you point me to a user download. I have looked on the SMA site but the user manual is basic.

I will have a look at the over voltage. I have not looked at Hugh's site for a while but will look at the schematic.

(1800w is not critical it can vary from this, indeed I would like to be able to vary the output to adjust the amount of heat output during the day but that is for later.)

P.S. I have looked at the link but it  appears to short out the PMA which slows it when wind powered but will make the Lister sweat! Hugh's site, however, looks ideal, his over voltage idea seems a goer. I will have a build and test it. If it works I will calibrate it to 450V which, according to Alan, is the best voltage to limit to. Thanks again A.L

Dick