Recent content by carlosduarte

  1. carlosduarte

    Rated short-time withstand current Icw for time different than stated

    Hello everybody. I have several flexible copper buscar Datasheets with different Icw values for times 0.2, 0.5 and 1s. I know it has to do with I^2t and there is a way to determine, for example, the Icw (1s) based on the Icw (0.2s) or Icw (0.5s) stated on the Datasheets. I need to compare the...
  2. carlosduarte

    Safety butterfly valve to shut off a penstock fl

    Boa noite. Muito bom cruzar-me com quem fala português. Thanks for your quick reply. I work for a Portuguese utility and all our hydro plants are equipped with safety shut off valves, not remotely resettable. It this, in fact, an utility requirement. I was just searching if there is a...
  3. carlosduarte

    Safety butterfly valve to shut off a penstock fl

    Good evening everybody. I’m an electrical engineer and I have a safety question regarding a safety butterfly valve that closes automatically after an excess flow detection. I’m familiar with these systems and, if the valve does close, I think it’s mandatory that the reset is always a manual...
  4. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Hello everybody I have data from a programmed outage of one of our generators. I´ve recorded the frequency excursion. I want to calculate the RoCoF from the acquired data. I have 1.25 ms samples of the grid frequency. I´ve worked them in Excel and came out with the following graph: The...
  5. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Good night James. I´ve downloaded the book from www.engineeringbookspdf.com I can calculate the inertia of our grid and predict the initial rate of change of frequency (ROCOF). But, after a real outage event, performing a "post-mortem" analysis of our data, I can measure the real RoCoF. I´ve...
  6. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Good afternoon Phil Corso and ControlsGuy25 . I´m not comparing apples and oranges. First things first. As I´ve reported, I´m interested on the SIR - synchronous inertial response - of our generators. I´m fully aware of the governors different technologies and speed responses. But, for...
  7. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Hello Controlsguy25. I´ve downloaded The electric generators handbook by Ion Boldea. The subject is now much clearer. I´m working on a report to my Dispatch Center colleagues. When finished, I will gladly share it. I have developed an excel macro-file that is capable to calculate, compare...
  8. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Hi there ControlsGuy25 and CSA. Thanks for all your help. I’ve had the chance to study chapter V: IMPACT OF LOW ROTATIONAL INERTIA ON POWER SYSTEM OPERATION. The question is that the figures it presents relates to continental Europe. Our grid has no tie lines and the whole system is fragile...
  9. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Hello Controlsguy25. I’ve been studying the docs that you’vê provided which were really enlightening. I’m from Portugal, Madeira island. I guess our grid is similar to French possessions like Martinique or Guadeloupe. An island. Equations 3 and 4 caught my attention: The RoCoF depends on...
  10. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Merci beaucoup. I‘ll keep you updated on the subject. Au revoir
  11. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Hello Controlsguy25. Thanks for your reply and doc provided. Let me clarify: We have old 14 MVA fuel generators, with mechanic speed governors, with 2 s H inertia constants. Then we have modern 21 MVA natural gas generators, with digital speed governors, but with only 1.34 s H inertia...
  12. carlosduarte

    SIR - Synchronous inertial response of generators with different inertia constants H

    Good afternoon Suppose I have two synchronous generators. One rated 10 MVA with H=4s and the other 20 MVA with H=2s. I understand that the SIRs of the generators don’t depend on their operating point. But if both are working at, let’s say, 5 MVA, and there’s an outage of another generator in...
  13. carlosduarte

    Pelton turbine minimum flow/power

    Good morning Phil Corso. I’m from Portugal, Madeira Island. I work for the island utility and we have eight hydro power stations, all with Pelton turbines. We are retrofitting two of those and that’s why I’m searching for informations on the minimum operational power of a turbine generator.
  14. carlosduarte

    Pelton turbine minimum flow/power

    Hello Phil. Thanks for your reply. The turbine is 25 years old and its manufacturer is no longer in the business. My main concern is not the damage on the buckets but the ones on the nozzle as you can see in the picture attached. The unsupported 25% rule of thumb is very questionable. I...
  15. carlosduarte

    Pelton turbine minimum flow/power

    Good morning everybody. I need your expert advices. We are retrofitting an hydro power plants with three Pelton turbines that drive 8 MW alternators. Historically, the turbines cannot be operated below 2 MW. But I cannot find any manufacturer documents that support this figure. I know that...
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