Generator Reactive Capability



Generator Reactive Capability

Temperature Sensitive Generators

Use of Temperature Curves

In order for a Generator to conduct an acceptable Reactive Capability Demonstration Test, the generator must achieve and hold Summer – Seasonal Claimed Capability (S-SCC) for the duration of the one-hour reactive test. In other words, the Generator will be compensated for the Lagging MVAR delivered to the transmission system while at its full MW output (established S-SCC).

Realizing that some generators are temperature sensitive and have established MW output curves based on ambient temperature for MW Claimed Capability demonstrations, the same MW output curves will be applied for MVAR demonstrations to assure that the generator has achieved it’s S-SCC MW output during a reactive test. However, they will only be used when ambient temperature is greater than 90 degrees and the generator can not reach it’s nominal S-SCC demonstrated at 90 degrees as displayed on its NX-12 form. It is conceivable that on a day cooler than 90 degrees that the generator could go higher than the MW established on the NX 12, however for the purpose of the Reactive test there is no need to exceed the 90-degree MW value. The reactive capability test is intended to demonstrate the capability of the generator, not the turbine for which the ambient temperature curves are intended to compensate.

Sample Temperature Curve

|Ambient Temp. |MW |MVAR |

| |NX 12 |NX-12D Curve |

| |Curve | |

|87 |53 |8.5 |

|88 |52 |9 |

|89 |51 |9.5 |

|90 |50 |10 |

|91 |49 |10.5 |

|92 |48 |11 |

|93 |47 |11.5 |

|94 |46 |12 |

|95 |45 |12.5 |

Nominal Day (90 Degrees)

In the sample temperature curve, the generator would be expected to demonstrate at the nominal 90-degree point of 50 MW and 10 MVAR for the full hour of the test.

Cooler Day (< 90 Degrees)

If the temperature is cooler than 90 degrees, the ability to achieve the 50 MW output should be easier, and there is no need to exceed the 50 MW output, the important point of the test is to demonstrate to 10 MVAR output at this MW level.

Hot Day (>90 Degrees)

If the temperature is higher than 90 degrees the turbine may not be able to drive the generator to the 50 MW level, therefore the temperature curve would be applied. In the sample curve, if the ambient temperature is 95-degrees the generator would be expected to achieve 45 MW, but the MVAR expectation would increase to 12.5 MVAR. If the generator cannot achieve this MVAR output and can only produce 11.5 MVAR for the full hour of the test, using the NX-12D curve, the reduction would be interpolated back to the 90-degree nominal level. In this example, that would be approximately 9 MVAR establishing a new VAR Capability qualifying for payment.

Note:

Generators will not be compensated for MVAR demonstrated above the NX-12D curve. If more VARs can be produced, a new NX-12D form must be submitted prior to demonstrating this higher level.

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