IEEE 1021-1988 pdf free.IEEE Recommended Practice for Utility Interconnection of Small Wind Energy Conversion Systems.
IEEE 1021 installer is responsible forproviding sitespecific information and drawingsindicating the physical location of the SwECSand of the lockable disconnect device (see 4.3.2).
Utility Outages.Since utility line configurations and impedances cover a very broadrange，reliable，costeffective and enforceablemethods for preventing the swECS system fromenergizing the utility line will require properdesign engineering and testing by the manufacturer,and review of field-operating experienceby the manufacturer and the utility.
The interconnection and protection require-ments that may be required to ensure reliablede-energization or disconnection from the utilityduring utility outages can vary with location,different utilities,utility systems,and swECScharacteristics.The ability of swECS to selfexcite or energize the utility line is a functionof the characteristics of the swECS electricalsystem, the equipment protection and safety protection devices installed, and the electric utilityline impedance characteristic.
The ability of an interconnected swECS to deenergize or disconnect from the electric utilityservice after a utility outage is probably the mostimportant SWECS electrical system characteristic. This characteristic directly affects thesafety of utility maintenance personnel,thesafety of the swECS owner, protection of utility equipment,protection of paralleled connected loads，and protection of the swECS electricalsystem.
Though a number of careful investigationshave been conducted, conflicting opinions existconcerning how different types of intercon-nected swECS (that is, those using synchronousgenerators，induction generators，or inverters)will react after a utility outage occurs. There isno consensus of opinion nor has there been suf-ficient field experience to provide a basis forspecific recommendations that will ensure 100%
reliable de-energization or disconnection of asWECS during a utility outage. For the mostpart, the uncertainty and differences of opinionare related to the reactions that may occur whena number of sWECS are concentrated in a smallarea of an electric utility system.The interconnected swECS may be re-quired to provide a means to prevent energizingor attempting to energize a deenergized utilityline.
The sWECS system should be de-ener-gized or disconnected from the utility system inless than one second upon occurrence of sustained abnormal voltage or frequency. Abnormal voltage is defined as voltage outside theoperating range permitted at the interconnection point by the local utility regulatory au-thority. Abnormal frequeney isdefined asfrequency less than 59.0 Hz or greater than61.o Hz. Utility technical considerations mayrequire tighter tolerances.
Sustained overvoltages may cause utility orcustomer equipment failure in much less thanone second. If the characteristics of the SwECSand the utility system are such that high overvoltages may occur, overvoltage protection withno intentional time delay may be required.IEEE 1021 pdf download.