A3 2010REPCpresentation Putnam Pehosh

Robert Putnam, P.E., CH2M HILL Renewable Energy Technical Services ManagerMichael Pehosh, P.E., NRECAPrincipal Distribution Engineer, Energy Policy : 

Robert Putnam, P.E., CH2M HILL Renewable Energy Technical Services ManagerMichael Pehosh, P.E., NRECAPrincipal Distribution Engineer, Energy Policy Interconnection of Large Wind Turbines to Co-op Distribution Grids

Purpose of this Presentation : 

To address the key engineering issues that need to be considered before interconnecting wind turbines to electric co-op distribution systems Discuss lessons-learned and post-installation operating experience through Cooperative Case Studies Purpose of this Presentation

Distribution Engineering Issues : 

Voltage flicker (during start-up and generator switching, if applicable) Voltage levels during turbine operation Proper operation of substation and line voltage regulators, circuit breakers and reclosers Protection of the grid and wind turbine(s) during grid disturbances Distribution Engineering Issues

Questions to be Asked : 

Does voltage stay within ANSI C84 limits? Do more tap changes and capacitor bank switching operations occur? Do system protection devices still coordinate properly? Are temporary overvoltages likely? Is voltage flicker noticeable or objectionable? Questions to be Asked

Voltage Flicker : 

Voltage Flicker

Solutions to Voltage Flicker : 

Interconnecting directly to the substation bus. Construction of a dedicated circuit to the substation. Downsizing the wind turbine. Re-conductoring the existing distribution circuit. Upgrading the substation transformer size. Moving the wind turbine closer to the substation. Installing Static VAR compensation. Adjusting the turbine controls. Solutions to Voltage Flicker

Voltage Control During OperationANSI C84.1 Voltage Limits : 

Voltage Control During OperationANSI C84.1 Voltage Limits

Solutions to Voltage Control Issues : 

Operating at a lower lagging power factor. Installing a Load Tap Changing substation transformer. Installing a substation bus voltage regulator. Installing line voltage regulators sensitive to reverse flow. Installing fixed and switched capacitors. Keep in mind however, that not all capacitor switching controls are created equal. Time and temperature are the least desirable, whereas current, voltage and Var controls are the most desirable. Solutions to Voltage Control Issues

Goals of Over-Current Protection : 

To prevent equipment damage and personal injury Detect all faults and clear them quickly Interrupt as few customers as possible Prevent unnecessary trips False trip (i.e., during an overload but not a fault) Sympathetic trip (i.e., during a fault outside the protective zone) Fuse saving Prevent loss of sensitivity Proper coordination must be achieved between devices (e.g., circuit breakers, reclosers, fuses) Goals of Over-Current Protection

IEEE 1547 : 

The scope of the Standard establishes criteria and requirements for the interconnection of distributed resources (DR) with electric power systems (EPS). It provides requirements relevant to the performance, operation, testing, safety considerations, and maintenance of the interconnection. IEEE 1547 consists of 7 parts, 4 of which are currently in draft form. IEEE 1547

IEEE 1547 (cont.) : 

Portions of the Standard relevant to the assessment and application of wind generation at the distribution system level include: Reclosing intervals and operation Undervoltage Overvoltage Negative Sequence V & I Frequency settings IEEE 1547 (cont.)

IEEE 1547 (cont.) : 

The National Rural Electric Cooperative Association (NRECA), the Cooperative Research Network (CRN), and the National Rural Utilities Cooperative Finance Corp. have worked together to develop a number of resources to help electric cooperatives address the legal, economic and technical issues raised by consumer-owned generation. These can be found on cooperative.com in the Distributed Generation tool kit section of the Engineering & Operations interest area. IEEE 1547 (cont.)

Case Studies – Illinois REC : 

Illinois Rural Electric Cooperative installed one (1) NM82 Vestas/NEG Micon Turbine rated at 1.65 MW. The unit has been operating since May 2005. The turbine is connected to a 12.47-kV Feeder (34.5-kV Source). In this case, coordination of overvoltage and undervoltage trip functions was found to be essential and the installation of two turbines would result in flicker and tap change issues. Case Studies – Illinois REC

Case Studies – East River EC : 

East River Electric Cooperative installed two Nordex N60/1300 turbines rated at 1.3 MW each on a 4/0 Cable, 1/3 Concentric Neutral, approximately 3,658 meters from a 69/12.47-kV Substation (Transformer, 3750 kVA). Even though the units were installed on a dedicated feeder, the utility still received complaints concerning voltage flicker. Solutions implemented consisted of turbine vendor-adjusted controls, Dynamic VAR Compensation, and a dedicated transformer (2500 kVA). Case Studies – East River EC

Case Studies – Iowa Lakes EC : 

Iowa Lakes Electric Cooperative’s (ILEC) investigation of wind generation’s potential in its service area benefited from the recent development of the ethanol industry, resulting in larger substations and related infrastructure serving extremely high load factor facilities. ILEC’s strategy was to deploy as many turbines as possible without adding a transmission-level interconnection and to take advantage of existing infrastructure. The resulting projects consisted of two 7-turbine (10.5 MW each) installations on 12.47 kV feeders commissioned in March 2009. Voltage issues, real or imagined, were common concerns among others (e.g., noise). Case Studies – Iowa Lakes EC

Conclusions : 

Conclusions Rural electric utilities can start to identify potential sites for wind turbines in an area with adequate wind resources by considering locations close to: Large substations and related infrastructure. Consider deploying distributed wind turbines in small clusters without having to add a transmission-level connection. On feeders with forecasted load growth (e.g., ethanol plants with a high load factor).

Conclusions (cont.) : 

Conclusions (cont.) Other opportunities to increase the economic feasibility and acceptance of distributed wind projects include: Partnering with others on a wind turbine order in order to attract interest from manufacturers and achieve economies of scale. Taking advantage of CREBs and other available incentives at the state and federal level. Being pro-active in addressing the issues of concerned citizens both for and against wind.

Conclusions (cont.) : 

Conclusions (cont.) System integration is the challenge for large wind installations. Interconnection requirements at transmission voltage are substantial and costly. New transmission lines are difficult to site and permit. On the other hand, interconnection can be easier for small installations, especially if the utility owns and operates the facility.

Thanks to: : 

Thanks to: Tom Wind, Wind Utility Consulting Tom McDermott, MelTran Sean Middleton, IREC Rick Olesen, Iowa Lakes EC UWIG

For Further Information : 

For Further Information NRECA, CRN and DOE Wind Powering America program are working together to develop a number of resources to help electric cooperatives address the legal, economic and technical issues raised by consumer-owned generation. Many of these resources can be found on www.cooperative.com including the Distributed Generation tool kit which details the application of IEEE 1547 Standard. Tools, support and experience are available from others as well, including www.repartners.org and the Utility Wind Integration Group (UWIG). Several Electric cooperatives are members of UWIG. More information can be found at: www.uwig.org.

Making Technology Work : 

Making Technology Work Thank You! robert.putnam@ch2m.com 1-315-751-2638 michael.pehosh@nreca.coop 1-703-907-5862