Hydro Generator Paralleling
Hydro Generator Paralleling
(OP)
Hi, I was wondering if anyone here could highlight possible issues faced with paralleling two HRG Hydro generators (same manufacturer, same size, same speed) to a common 5kV bus, and subsequently out to the utility through a common transfomer.
Assuming, both generators have same type of voltage regulators with the same type of droop compensation (hopefully avoiding circulating currents) what other issues may there be to look out for?
Thanks!
Assuming, both generators have same type of voltage regulators with the same type of droop compensation (hopefully avoiding circulating currents) what other issues may there be to look out for?
Thanks!






RE: Hydro Generator Paralleling
Check Basler and Woodward websites for technical data on parallel operation of generators.
RE: Hydro Generator Paralleling
Basler definitely has some good documentation.
RE: Hydro Generator Paralleling
You can probably get online and export to a utility with almost any governor settings, but if the sets are going to be islanded at any time, the governor characteristics and settings should be the same.
respectfully
RE: Hydro Generator Paralleling
In the couple to the grid.. you could use a regulator with a voltage matching.. or to raise or reduce voltage with your syncro device working on the AVR... the same with the frequency, you will control the speed regulator with the syncro device... there´s a lot of manufacturer... and you could adjust the window of syncronism... depending on the generator and the utility, you could use a more or less restrictive window...
About protections, i think you will need... in all the sizes of machine... Overvoltage, minimum voltage, overcurrent protections, to earth, overload, between phases with differents curves for trip... and it´s needed to know the way it´s grounded cause depending on this you will use one adjustment or other....reverse power, excesive capacitive (seen from the machine side) current... if you use a Basler 200 you got inside regulator... differencial protection on the generator side and transformer...
I like a lot the multiline (GE) or Sepam ...
If your work on a separated grid, the thing is more easy,
you´ll work normally on droop or cross compensation, and the idea is to make the two machines take the same amount of reactive load, and in the governor side, for the speed, is the same, with the same load.. the governor have to be with the same droop...you could adjust it a little high from the 60 or 50 hz...
i hope this will help
RE: Hydro Generator Paralleling
RE: Hydro Generator Paralleling
Waross, sounds like once we are tied to a grid (especially since there are small units - 5MW each), there really aren't many concerns (different from a single generator facility) after ensuring the regurlators are set similarly.
motoxplosion, as you mention there are some strict protection requirements both posed by the utility and ourselves on these units. I am confident we have met all requirements in this regard.
RE: Hydro Generator Paralleling
Voltage regulator settings will set VAR production.
Governor speed setting and governor droop will control KW production. The droop setting is not very important, BUT, if you have two machines that are paralleled and may be islanded with a significant load, such as an industrial plant that produces enough power to supply in plant needs and also export power, the droop settings should match as close as possible.
When two machines with unequal droop settings are paralleled AND islanded, they may be set to share the load at ONE power level. Either an increase or decrease of the load may cause unequal load sharing to the point that one machine is overloaded.
Good practice dictates that the governors be set as close as possible, despite what will work and what you can get away with.
RE: Hydro Generator Paralleling
True if the generator is small relative to the grid at the point of connection. A pair of 5MW generators will likely be able to exert significant influence on the voltage of a distribution system unless they are connected close to a major distribution node where the system is 'stiff' and able to absorb VArs without significant voltage variation. It is not unusual to run the AVR in power factor control at a near-unity PF.
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Sometimes I wake up Grumpy.
Other times I just let her sleep!
RE: Hydro Generator Paralleling
An old worn out diesel generating plant that was mothballed when the transmission lines from a new, remote hydro generating station arrived in town.
Twenty or more years later the old diesels were started up and put online at low throttle settings (low KW output) and high excitation to supply VARs to both reduce the line losses and to boost the terminal voltage of the transmission line.
Respectfully
RE: Hydro Generator Paralleling
Our intention (if the Utility allows) is to run in PF mode at or near unity, but often times we are requested to assist with voltage support.
From what I can tell from these responses there are not many issues to be concerned with when parelling two units. I was interested to see whether there would be comments such as: utilize a single HRG between both units not one HRG connection for each, or make sure to use cross current compensation not droop etc.
Thanks,
RE: Hydro Generator Paralleling
I don't do much with small embedded machines but I would expect standard droop control will be very workable against a large and stiff utility connection. Again it depends on where the machines parallel - if they share an LV bar then they will have more influence over each other because they are effectively decoupled from the utility by the transformer impedance. If they have no common coupling until the 69kV level then they will have virtually no interaction.
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Sometimes I wake up Grumpy.
Other times I just let her sleep!