5.7 Evaluation of Generator Reactive Capability
FERC issued an Order 827 on June 16, 2016 that requires all newly interconnecting non-synchronous generators, including wind generators, to provide dynamic reactive power within the range of 0.95 leading to 0.95 lagging at the high-side of the generator substation unless the transmission provider has established a different power factor range that applies to all non-synchronous generators in the transmission provider’s control area on a comparable basis. These new non-synchronous generators are required to maintain a composite power delivery at continuous rated power output.
Non-synchronous generators may meet the dynamic reactive power requirement by utilizing a combination of the inherent dynamic reactive power capability of the inverter, dynamic reactive power devices (e.g., Static VAR Compensators), and static reactive power devices (e.g., capacitors) to make up for losses.
FERC accepted the CAISO compliance filing to implement this requirement. The requirement is applicable to:
· An existing asynchronous generating facility making upgrades to its generating units after September 21, 2016
· Asynchronous generating facilities submitting a written request to continue a re-study under Section 6.4 of Appendix U of the CAISO tariff on or after September 21, 2016
· An interconnection customer posts the Interconnection Financial Security for an asynchronous generating facility pursuant to Appendix DD if the CAISO tariff section 11.2.2 on or after September 21, 2016
· An interconnection customer that submits an interconnection request for an asynchronous generating facility under the Fast Track process on or after September 21, 2016
For synchronous generators the requirements did not change and the Generating Unit is required to maintain a composite power delivery at continuous rated power output at the terminals of the Electric Generating Unit at a power factor within the range of 0.95 leading to 0.90 lagging. Such requirement can be verified from the generator capability curve directly.
A white paper was published on February 25, 2019 focusing on the methodology to evaluate reactive capability of asynchronous generators and establishes a common approach for the CAISO and all Participating TOs to evaluate the reactive capability of newly interconnecting generators in the interconnection studies. The actual operational capability shall be verified when the generator achieves commercial operation and not addressed here.
The guidelines presented in the February 25, 2019 white paper are to ensure that all PTOs use a consistent approach when evaluating the reactive capabilities of new generation. PTOs may deviate from these procedures as long as the following general principles are followed:
1. If a generator can meet the power factor requirement under normal conditions but is deficient under extreme conditions, the IC can mitigate the deficiency by using an automated control scheme to derate the real power output of the generator in order to meet the reactive power requirement.
2. Generators that are capable of providing more reactive support than required are modeled in the studies providing only the required amount.
For details on the methodology that is applied to evaluate a generator’s reactive capability in the generation interconnection studies, the white paper is available on the CAISO website.