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What is Interconnection and Transmission?
Connecting to the Grid (Large Wind Turbines) Important Information About Large Turbine Projects |
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What is Interconnection and Transmission? Connecting to the Grid (Large Wind Turbines)
If you plan to connect your turbine to the existing power grid, you must make sure that your turbine is near a three-phase power line. Also, some utilities restrict how close a turbine can be to power lines, so make sure you know that ahead of time. The power lines you connect to must have the capacity to handle the added electricity from your turbine. You should start talking to a local electric distribution company in the early stages of planning your project. For large wind farms, the proximity to existing transmission lines is critical to minimizing infrastructure requirements and keeping costs down. High voltage lines can cost $50,000 per mile, so sites with good wind with access to transmission capacity can be very valuable. Single turbines and small clusters will have an easier time finding available transmission lines, but there are no guarantees until you check.
In order to sell your electricity, you must connect your project to the electricity grid. Finding a location to establish this interconnection will play almost as important a role in choosing your site as wind resource. A very windy location without access to the electricity grid will not be suitable for most wind projects (the exception being off-grid systems). Interconnection can be in the form of connecting to a power line or attaching to a substation. For large turbines, the power line or substation must have three-phase power and the appropriate voltage (typically 12 kV, 24 kV, or 34.5 kV for one or two large turbines) to handle your electricity. If you do not know the voltage of power lines near your site or if you do not know who owns them, start talking with the local utility company; they should be able to help learn more.
Interconnect Study. The owner of the power line or substation you wish to connect to can determine whether the facility is appropriate for your project and whether it has available capacity for your power. This determination is made through an interconnect study, which sometimes can be quite expensive and take several months (or more) to complete. ComEd publishes a "Blue Book": Guidelines for Interconnection of Generation to the ComEd System, available from them for $50. Some ComEd interconnection procedure information also is available online: www.comedtransmission.com/trsfiles/attachment-k.doc For other utilities, ask if they offer a similar publications to guide you through the process. The resulting study will tell you whether you will be allowed to interconnect, and if so, what kinds of electrical equipment need to be installed (at your expense).
Interconnection Agreement. When the interconnect study is complete, you will need to negotiate an interconnection agreement with the utility. This agreement will include a detailed design of the interconnection; specific costs; any limitations on operation of your turbine such as times when your generator can and cannot run; and what power quality, metering, and safety measures must be taken. You need to carefully analyze and add up the costs associated with the interconnection agreement.
Transmission Service. Transmission service is necessary to move your electricity on the utility grid. If the buyer of your electricity is not the same as the owner of the transmission lines, there will be additional charges (wheeling charges). These charges can be significant and need to be factored into the economics of your project. You also need to consider that "line losses" can reduce the amount of electricity you can sell by up to 10 percent.Important Information About Large Turbine Projects