The Federal Energy Regulatory Commission (FERC) is proposing to amend its regulations to require public utilities to include specific technical provisions for wind energy in their open access transmission tariffs (OATTs). The new rules will allow wind power projects to be integrated more firmly into the existing transmission system.
The main feature of the new rules is to allow wind projects to ride out disturbances and remain connected to the transmission grid – a process called low-voltage ride through. Once the new standard is approved, all wind projects 20 MW and larger will have to have electronic equipment that will monitor and support the transmission grid during periods of disturbance.
On the issue of low-voltage ride through, FERC’s proposal reads:
Prior to the advent of larger wind plants generally consisting of multiple wind generation turbines, individual wind turbines were designed to go offline if there was a sudden change in voltage on the transmission system. However, now there are larger aggregated wind plants with a greater penetration level on the Transmission Provider’s systems in certain areas, and significant stability problems can occur on the transmission system if such large plants become unavailable during a low voltage excursion. As a result, Transmission Providers need large wind plants to remain online during low-voltage occurrences for reliability reasons.
The Commission is proposing to require that large wind plants seeking to interconnect to the grid demonstrate low voltage ride-through capability, unless waived by the Transmission Provider on a comparable and not unduly discriminatory basis.
FERC is also seeking comments on proposed changes to the requirements for Supervisory Control and Data Acquisition (SCADA) Capability and Power Factor Design Criteria (Reactive Power).
Previously, Transmission Providers generally did not require wind generators to have remote supervisory control and data acquisition (SCADA) capability because of their small size and minimal effects on the transmission system. Now that there are more large wind plants, Transmission Providers may need SCADA capability to ensure the safety and reliability of the transmission system during normal, system emergency, and system contingency conditions, and to acquire wind facility operating data.
The Commission proposes to require that large wind plants seeking to interconnect to the transmission grid possess SCADA capability. Particularly, the Commission seeks comments on whether there is any basic essential SCADA information that large wind plants should be required to provide, and if so, what that information should be (such as information needed to determine how the plant’s maximum megawatt output and megawatt ramp rate vary over time with changes in the wind speed, and/or information needed to forecast the megawatt output of the plant).
Previously, Transmission Providers did not require wind generators to have the capability to provide reactive power because the facilities were generally small and had minimal impact on the transmission grid. Because of the larger size of many of the wind plants currently operating and the increased penetration of wind energy on the transmission system, Transmission Providers may need to require wind plants to operate within a specified power factor range to help balance the reactive power needs of the transmission system.
The Commission is proposing to require that wind plants maintain a power factor within the range of 0.95 leading to 0.95 lagging (as required by Order No. 2003), to be measured at the high voltage side of the substation transformer. Additionally, the Commission proposes to allow the Transmission Provider to waive the power factor requirement for wind plants where such capability is not needed at that location or for a generating facility of that size, provided that such waiver is not unduly discriminatory and is offered on a comparable basis to similarly situated wind plants.
Comments on FERC’s proposals are due March 2, 2005. Reply comments will be due 30 days thereafter. Here is a link to FERC’s Proposed Rule for Wind Power Interconnection. Comments may be filed electronically using e-Filing on the Commission’s Web site.
The new rules are expected to be minimally disruptive for wind turbine manufacturers and the costs of the new technology is not expected to be significant. Many of the proposed rules were put forward by the wind industry’s trade association – The American Wind Energy Association.