NFPA 110& IEEE446-S"k- V&F dynamics???

[brmamor2]

Key word: NFPA110 - IEEE446- max %V & % F dip- S"k (Transient short Circuit Power) - KVA motor starting - Droop & Isochronous

Sir
Herein some questions on standards defining dynamics on a power generation / standby power /emergency power projects design: I'm trying to be fixed on the choice of criteria for defining dynamic performance on a power distribution in a power plant for starting heavy motor by diesel engine in a black start condition.

What about the NFPA 110 (specially the paragraph 5- 13.2.6) and IEEE446? Did they fix dynamic performances? Any value to be fixed in a specification? (I don't have these standards)
What about the step load acceptance test: frequency and voltage dips: are they standardized? I believe that 12.5% of voltage dip for full load step on a diesel engine for example with 2s recovery time to stable operation (+/-2% of rated volt) are applicable, but is this not so sever? What about frequency dip acceptance criteria? How many hertz could be accepted and for how much time?

I sow also in a single line diagram for an LCI for gas turbine generator that they ask for a minimum of S"k with maximum voltage variation to be insured by the black start design. I understand this can quantify the load impact for the design of a power system distribution; can any one enhance this subject and show me the correlation with what in the first paragraph could be defined above?
Any document, kind of specification or web address would be really grateful.
Best regards.

Roma

 

[alehman]

5-13.2.6 doesn't seem to be a valid paragraph number in the current 110. 110 does not give specific performance criteria. It states the following:

5.6.9.8 Generator system performance (i.e., prime mover, generator, exciter, and voltage regulator, as applicable when prototype tested as specified in 5.2.1.2) shall be as follows:
(1) Stable voltage and frequency at all loads shall be provided to full-rated loads.
(2) Values consistent with the user's needs for frequency droop and voltage droop shall be maintained.
(3) Voltage dip at the generator terminals for the maximum anticipated load change shall not cause disruption or relay dropout in the load.
(4) Frequency dip and restoration to steady state for any sudden load change shall not exceed the user's specified need.
6.2.7 Time Delay on Transfer to EPS. An adjustable time-delay device shall be provided to delay transfer and sequence load transfer to the EPS to avoid excessive voltage drop when the transfer switch is installed for Level 1 use.

IEEE 443 is also vague. This is because motor starting performance cannot be specified by simple criteria. Most generator sets specify a maximum motor starting kVA. For induction motors, a rule of thumb is 0.5hp/kW. Motor starting design involves complex calculations that are best performed by computer simulation suck as SKM Transient Motor starting module. The generator manufacturer may also have motor starting analysis software.

 

[brmamor2]

Thanks alehman