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Re: [microhydro] Best option for a generator

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  • nando37
    Since you have a 400 volts 3 phase arriving from the Grid, then it is best to have an induction motor with 3 phase feeding the GRID NO need t have DC motor and
    Message 1 of 10 , Jun 12, 2013
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      Since you have a 400 volts 3 phase arriving from the Grid, then it is best to have an induction motor with 3 phase feeding the GRID NO need t have DC motor and inverter it is totally an excess in the design.

      When the Grid drops then the site can produce power locally  with such 12 KW and of course you will need a ballast controller capable of controlling the power generated when isolated from the Grid.

      You will as well require a small circuit when the process of connection to the Grid for easy connection without power glitches.

      Please state the head and the water volume and the pipe ( penstock ) length and diameter.

      Nando


      On 6/12/2013 04:30, arrow28r@... wrote:
       

      Hi
      We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
      There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
      We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
      The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
      Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
      We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
      Thanks
      Peter


    • arrow28r@rocketmail.com
      The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with
      Message 2 of 10 , Jun 13, 2013
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        The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **

        --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
        >
        > Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
        >
        > Jeff Grebe
        >
        > > To: microhydro@yahoogroups.com
        > > From: arrow123@...
        > > Date: Wed, 12 Jun 2013 09:30:28 +0000
        > > Subject: [microhydro] Best option for a generator
        > >
        > > Hi
        > > We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
        > > There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
        > > We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
        > > The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
        > > Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
        > > We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
        > > Thanks
        > > Peter
        > >
        > >
        > >
        > > ------------------------------------
        > >
        > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide!
        > >
        > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way.
        > >
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        > >
        > > To unsubscribe: send empty message to microhydro-unsubscribe@...! Groups Links
        > >
        > >
        > >
        >
      • arrow28r@rocketmail.com
        Thanks Nando I will get the details from the engineer when he is around next, may be a day or two. I have walked the proposed pipe route - it is through
        Message 3 of 10 , Jun 13, 2013
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          Thanks Nando

          I will get the details from the engineer when he is around next, may be a day or two. I have walked the proposed pipe route - it is through native bush, so will be another challenge to get it there. The stream is being monitored at the moment, so will get details as soon as I can.
          Peter

          --- In microhydro@yahoogroups.com, nando37 <nando37@...> wrote:
          >
          > Since you have a 400 volts 3 phase arriving from the Grid, then it is
          > best to have an induction motor with 3 phase feeding the GRID NO need t
          > have DC motor and inverter it is totally an excess in the design.
          >
          > When the Grid drops then the site can produce power locally with such
          > 12 KW and of course you will need a ballast controller capable of
          > controlling the power generated when isolated from the Grid.
          >
          > You will as well require a small circuit when the process of connection
          > to the Grid for easy connection without power glitches.
          >
          > Please state the head and the water volume and the pipe ( penstock )
          > length and diameter.
          >
          > Nando
          >
          >
          > On 6/12/2013 04:30, arrow28r@... wrote:
          > >
          > > Hi
          > > We have a pelton turbine rated at 1000rpm available to use for a
          > > microhydro project in our area. The site is in a conservation area
          > > where the water supply will be from a stream approx 1km from the
          > > proposed powerstation site. Calculations and work on the current site
          > > show a capacity for 12kW from the stream, which lines up fairly well
          > > with the load at the site. This site is currently supplied from the
          > > grid and the owners of the training centre at the site would like to
          > > reduce their reliance on grid supplied electricity as they are at the
          > > end of a very long line. This Overhead line is supplied at 11kV 50Hz
          > > and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
          > > There are other Transformer sites along the length of the line as
          > > well. There is no desire to try to supply them during periods that the
          > > overhead line is down due to the distance from the centre.
          > > We hope to be able to supply the centre at 400V and synchronise with
          > > their 400V grid supply. The load in the centre fluctuates weekly as
          > > school groups are on site for a few days then the centre usage drops
          > > until the next group arrive. This fluctuation in load would be from
          > > 3kw to 20kw with it averaging around 12kw during the time the groups
          > > are on site.
          > > The centre would like to export any excess to the grid as they can be
          > > credited for any generation by the retailer.
          > > Following this long winded explanation, my question is what would be
          > > the best generator to connect to the turbine to allow us to generate
          > > up to 12kW, to synchronise to the grid and to supply the centre.
          > > We have considered both an induction motor and a DC motor and
          > > invertor, but am open to suggestions and would appreciate the groups
          > > thoughts on the best option for our situation.
          > > Thanks
          > > Peter
          > >
          > >
          >
        • Jeff Grebe
          One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also
          Message 4 of 10 , Jun 13, 2013
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            One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also makes it impossible to generate when the grid is down.  If the grid is unreliable it might be better to go synchronous alternators.  More equipment required to synch up but able to operate stand alone.  I've tried to supply an artificial "grid" waveform to a induction generator but ran into problems with the alternator driving the source and mucking up the works.  Maybe someone else has ideas on how to do this


             
            Jeff  Grebe

             
            > To: microhydro@yahoogroups.com
            > From: arrow123@...
            > Date: Thu, 13 Jun 2013 20:26:54 +0000
            > Subject: [microhydro] Re: Best option for a generator
            >
            > The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **
            >
            > --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
            > >
            > > Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
            > >
            > > Jeff Grebe
            > >
            > > > To: microhydro@yahoogroups.com
            > > > From: arrow123@...
            > > > Date: Wed, 12 Jun 2013 09:30:28 +0000
            > > > Subject: [microhydro] Best option for a generator
            > > >
            > > > Hi
            > > > We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
            > > > There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
            > > > We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
            > > > The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
            > > > Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
            > > > We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
            > > > Thanks
            > > > Peter
            > > >
            > > >
            > > >
            > > > ------------------------------------
            > > >
            > > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide!
            > > >
            > > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way.
            > > >
            > > > More information on micro hydropower at http://microhydropower.net
            > > >
            > > > To unsubscribe: send empty message to microhydro-unsubscribe@...! Groups Links
            > > >
            > > >
            > > >
            > >
            >
            >
            >
            >
            > ------------------------------------
            >
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            >
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          • arrow28r@rocketmail.com
            Thankyou for that info, I was wondering if capacitors across the generator terminals would be sufficient to maintain generation if the grid disappeared. The
            Message 5 of 10 , Jun 15, 2013
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              Thankyou for that info, I was wondering if capacitors across the generator terminals would be sufficient to maintain generation if the grid disappeared. The idea of generating when eth network is down is critical to the design of the whole project as this site is prone to heavy snow and road closures - last year we had to access the area by helicopter to fix the network lines so they were without electricity for several days. We would like to give them the ability to continue generating when the network is not available. Thanks again
              Peter

              --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
              >
              > One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also makes it impossible to generate when the grid is down. If the grid is unreliable it might be better to go synchronous alternators. More equipment required to synch up but able to operate stand alone. I've tried to supply an artificial "grid" waveform to a induction generator but ran into problems with the alternator driving the source and mucking up the works. Maybe someone else has ideas on how to do this
              >
              >
              >
              > Jeff Grebe
              >
              > > To: microhydro@yahoogroups.com
              > > From: arrow123@...
              > > Date: Thu, 13 Jun 2013 20:26:54 +0000
              > > Subject: [microhydro] Re: Best option for a generator
              > >
              > > The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **
              > >
              > > --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@> wrote:
              > > >
              > > > Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
              > > >
              > > > Jeff Grebe
              > > >
              > > > > To: microhydro@yahoogroups.com
              > > > > From: arrow123@
              > > > > Date: Wed, 12 Jun 2013 09:30:28 +0000
              > > > > Subject: [microhydro] Best option for a generator
              > > > >
              > > > > Hi
              > > > > We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
              > > > > There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
              > > > > We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
              > > > > The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
              > > > > Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
              > > > > We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
              > > > > Thanks
              > > > > Peter
              > > > >
              > > > >
              > > > >
              > > > > ------------------------------------
              > > > >
              > > > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide!
              > > > >
              > > > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way.
              > > > >
              > > > > More information on micro hydropower at http://microhydropower.net
              > > > >
              > > > > To unsubscribe: send empty message to microhydro-unsubscribe@! Groups Links
              > > > >
              > > > >
              > > > >
              > > >
              > >
              > >
              > >
              > >
              > > ------------------------------------
              > >
              > > Does your company feature in the microhydro business directory at http://microhydropower.net/directory ? If not, please register free of charge and be exposed to the microhydro community world wide!
              > >
              > > NOTE: The advertisements in this email are added by Yahoogroups who provides us with free email group services. The microhydro-group does not endorse products or support the advertisements in any way.
              > >
              > > More information on micro hydropower at http://microhydropower.net
              > >
              > > To unsubscribe: send empty message to microhydro-unsubscribe@...! Groups Links
              > >
              > >
              > >
              >
            • Jeff Grebe
              I have never run across a method of keeping an induction alternator on line without a source voltage. Pretty sure capacitors won t do it. J Grebe mobileSent
              Message 6 of 10 , Jun 15, 2013
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                I have never run across a method of keeping an induction alternator on line without a source voltage. Pretty sure capacitors won't do it.

                J Grebe mobileSent from my iPhone

                On Jun 15, 2013, at 1:49 AM, "arrow28r@..." <arrow123@...> wrote:

                > Thankyou for that info, I was wondering if capacitors across the generator terminals would be sufficient to maintain generation if the grid disappeared. The idea of generating when eth network is down is critical to the design of the whole project as this site is prone to heavy snow and road closures - last year we had to access the area by helicopter to fix the network lines so they were without electricity for several days. We would like to give them the ability to continue generating when the network is not available. Thanks again
                > Peter
                >
                > --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
                >>
                >> One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also makes it impossible to generate when the grid is down. If the grid is unreliable it might be better to go synchronous alternators. More equipment required to synch up but able to operate stand alone. I've tried to supply an artificial "grid" waveform to a induction generator but ran into problems with the alternator driving the source and mucking up the works. Maybe someone else has ideas on how to do this
                >>
                >>
                >>
                >> Jeff Grebe
                >>
                >>> To: microhydro@yahoogroups.com
                >>> From: arrow123@...
                >>> Date: Thu, 13 Jun 2013 20:26:54 +0000
                >>> Subject: [microhydro] Re: Best option for a generator
                >>>
                >>> The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **
                >>>
                >>> --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@> wrote:
                >>>>
                >>>> Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
                >>>>
                >>>> Jeff Grebe
                >>>>
                >>>>> To: microhydro@yahoogroups.com
                >>>>> From: arrow123@
                >>>>> Date: Wed, 12 Jun 2013 09:30:28 +0000
                >>>>> Subject: [microhydro] Best option for a generator
                >>>>>
                >>>>> Hi
                >>>>> We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
                >>>>> There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
                >>>>> We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
                >>>>> The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
                >>>>> Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
                >>>>> We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
                >>>>> Thanks
                >>>>> Peter
                >
              • Jeff Grebe
                Let me modify that answer a bit. I think its possible to keep an induction alternator running without the grid through self excitation (though it is seldom
                Message 7 of 10 , Jun 15, 2013
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                  Let me modify that answer a bit. I think its possible to keep an induction alternator running without the grid through self excitation (though it is seldom done, see below) but difficult to black start an induction alternator. Added to that problem is the requirement that you physically disconnect from the grid when operating stand alone to prevent from back-feeding a presumed dead grid. That would require a transfer switch. When you disconnect, the generator will overspeed and shut down requiring a black start One of the primary reasons to use an induction alternator is this self limiting generation on the loss of utility power.

                  --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
                  >
                  > I have never run across a method of keeping an induction alternator on line without a source voltage. Pretty sure capacitors won't do it.
                  >
                  > J Grebe mobileSent from my iPhone
                  >
                  > On Jun 15, 2013, at 1:49 AM, "arrow28r@..." <arrow123@...> wrote:
                  >
                  > > Thankyou for that info, I was wondering if capacitors across the generator terminals would be sufficient to maintain generation if the grid disappeared. The idea of generating when eth network is down is critical to the design of the whole project as this site is prone to heavy snow and road closures - last year we had to access the area by helicopter to fix the network lines so they were without electricity for several days. We would like to give them the ability to continue generating when the network is not available. Thanks again
                  > > Peter
                  > >
                  > > --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@> wrote:
                  > >>
                  > >> One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also makes it impossible to generate when the grid is down. If the grid is unreliable it might be better to go synchronous alternators. More equipment required to synch up but able to operate stand alone. I've tried to supply an artificial "grid" waveform to a induction generator but ran into problems with the alternator driving the source and mucking up the works. Maybe someone else has ideas on how to do this
                  > >>
                  > >>
                  > >>
                  > >> Jeff Grebe
                  > >>
                  > >>> To: microhydro@yahoogroups.com
                  > >>> From: arrow123@
                  > >>> Date: Thu, 13 Jun 2013 20:26:54 +0000
                  > >>> Subject: [microhydro] Re: Best option for a generator
                  > >>>
                  > >>> The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **
                  > >>>
                  > >>> --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@> wrote:
                  > >>>>
                  > >>>> Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
                  > >>>>
                  > >>>> Jeff Grebe
                  > >>>>
                  > >>>>> To: microhydro@yahoogroups.com
                  > >>>>> From: arrow123@
                  > >>>>> Date: Wed, 12 Jun 2013 09:30:28 +0000
                  > >>>>> Subject: [microhydro] Best option for a generator
                  > >>>>>
                  > >>>>> Hi
                  > >>>>> We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
                  > >>>>> There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
                  > >>>>> We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
                  > >>>>> The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
                  > >>>>> Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
                  > >>>>> We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
                  > >>>>> Thanks
                  > >>>>> Peter
                  > >
                  >
                • nando37
                  An induction motor as a generator when connected to the GRID and the motor driven by a turbine at rated RPM Plus the % slip the motor will become a generator
                  Message 8 of 10 , Jun 15, 2013
                  • 0 Attachment
                    An induction motor as a generator when connected to the GRID and the motor driven by a turbine at rated RPM Plus the % slip the motor will become a generator that is automatically synchronized to the GRID in frequency and voltage -- this if the motor windings are rated to produce the same voltage level than the GRID  and the RPM plus % slip to produce the same frequency. -- There is a PF consideration  that is determined by the torque of the turbine in reference to the Grid properties that it is a bit extensive to explain here.

                    There are methods to keep the induction generator synchronized to the GRID without being connected to the Grid but it is just a way to prove that can be done, you will need capacitors and a ballast controller sensitive to the zero crossing of the sine wave with a PWM % control .

                    Nando


                    On 6/15/2013 16:14, Jeff Grebe wrote:
                     

                    I have never run across a method of keeping an induction alternator on line without a source voltage. Pretty sure capacitors won't do it.

                    J Grebe mobileSent from my iPhone

                    On Jun 15, 2013, at 1:49 AM, "arrow28r@..." <arrow123@...> wrote:

                    > Thankyou for that info, I was wondering if capacitors across the generator terminals would be sufficient to maintain generation if the grid disappeared. The idea of generating when eth network is down is critical to the design of the whole project as this site is prone to heavy snow and road closures - last year we had to access the area by helicopter to fix the network lines so they were without electricity for several days. We would like to give them the ability to continue generating when the network is not available. Thanks again
                    > Peter
                    >
                    > --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@...> wrote:
                    >>
                    >> One caution on using induction alternators, as Nando pointed out the field is supplied by the grid which simplifies the paralleling with the grid but also makes it impossible to generate when the grid is down. If the grid is unreliable it might be better to go synchronous alternators. More equipment required to synch up but able to operate stand alone. I've tried to supply an artificial "grid" waveform to a induction generator but ran into problems with the alternator driving the source and mucking up the works. Maybe someone else has ideas on how to do this
                    >>
                    >>
                    >>
                    >> Jeff Grebe
                    >>
                    >>> To: microhydro@yahoogroups.com
                    >>> From: arrow123@...
                    >>> Date: Thu, 13 Jun 2013 20:26:54 +0000
                    >>> Subject: [microhydro] Re: Best option for a generator
                    >>>
                    >>> The network and energy retailers will allow import/export metering so we were trying to make the most of the available generation by exporting to the grid with any excess. ** :-) I like the thought of you heading this way to design it, but there probably isn't any funding available - we are doing this as a community service for an alpine trust group that run training and challenge courses for school groups, so am working on it after work hours and weekends when we can. You would like the area it is proposed to install at - native bush, alpine, very nice - I will post photos as soon as there any progress **
                    >>>
                    >>> --- In microhydro@yahoogroups.com, Jeff Grebe <jeffgrebe@> wrote:
                    >>>>
                    >>>> Induction AC alternator will be the most efficient, cheapest and most reliable. Very straight forward process if the utility will allow net metering or a bi-directional meter. Buy me a ticket and I'll come down to design/ install it!
                    >>>>
                    >>>> Jeff Grebe
                    >>>>
                    >>>>> To: microhydro@yahoogroups.com
                    >>>>> From: arrow123@
                    >>>>> Date: Wed, 12 Jun 2013 09:30:28 +0000
                    >>>>> Subject: [microhydro] Best option for a generator
                    >>>>>
                    >>>>> Hi
                    >>>>> We have a pelton turbine rated at 1000rpm available to use for a microhydro project in our area. The site is in a conservation area where the water supply will be from a stream approx 1km from the proposed powerstation site. Calculations and work on the current site show a capacity for 12kW from the stream, which lines up fairly well with the load at the site. This site is currently supplied from the grid and the owners of the training centre at the site would like to reduce their reliance on grid supplied electricity as they are at the end of a very long line. This Overhead line is supplied at 11kV 50Hz and a Transformer on site (30kVA) supplies the centre at 400V 3 phase.
                    >>>>> There are other Transformer sites along the length of the line as well. There is no desire to try to supply them during periods that the overhead line is down due to the distance from the centre.
                    >>>>> We hope to be able to supply the centre at 400V and synchronise with their 400V grid supply. The load in the centre fluctuates weekly as school groups are on site for a few days then the centre usage drops until the next group arrive. This fluctuation in load would be from 3kw to 20kw with it averaging around 12kw during the time the groups are on site.
                    >>>>> The centre would like to export any excess to the grid as they can be credited for any generation by the retailer.
                    >>>>> Following this long winded explanation, my question is what would be the best generator to connect to the turbine to allow us to generate up to 12kW, to synchronise to the grid and to supply the centre.
                    >>>>> We have considered both an induction motor and a DC motor and invertor, but am open to suggestions and would appreciate the groups thoughts on the best option for our situation.
                    >>>>> Thanks
                    >>>>> Peter
                    >


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