Forward(This Foreword is not a part of IEEE Std 1020-1988@ IEEE Guide for Control of Small Hydroelectric Power Plants.) Initially this document was planned to be a recommended guide strictly for the application of control systems to small hydroelectric power plants@ one type of dispersed generation source. As work progressed@ however@ it was seen that such a guide would be lacking in depth if some treatment of the controlled electrical and mechanical systems and equipment were not made. For completeness@ it was considered desirable to also mention salient civil features of small hydroelectric projects@ and to offer discussion of equipment protection and operation. The end result of this effort@ although termed a guide to control of small hydroelectric power plants@ is basically a tutorial document that presents descriptive information for use in planning the control system design and operation of small hydroelectric power plants. It is intended to provide a working knowledge of the terminology used in this field and an understanding of the principles of operation of hydroelectric generating units. It addresses the control requirements from an electrical standpoint. It does not discuss in any great detail the civil@ hydraulic@ and mechanical considerations that must also be taken into account when planning a hydroelectric project. It deliberately omits discussion of topics such as economics@ environmental factors@ financing@ and licensing. This document was prepared by a Task Force of the Working Group on Hydro Plant Controls of the Hydroelectric Power Subcommittee of the IEEE Energy Development and Power Generation Committee. Members of this Task Force represent a cross-section of the hydroelectric power industry@ including power plant owners@ designers@ and equipment manufacturers. The persons listed below were members of the Task Force when the Guide was ?nalized and submitted for balloting. E. T. Voelker @ Chair R. E. Howell @ Vice Chair S. R. Brockschink H. Butz H. E. Church@ Jr. H. R. Davis C. R. Desrosiers P. F. Garcia J. H. Gurney J. H. Jones R. F. Karlicek D. L. Kornegay J. E. LeClair P. Micale D. R. McCabe W. R. Moon G. D. Osburn L. Pereira B. J. Polk J. Quinn D. Seely B. Zarlenga The persons listed below also contributed to the preparation of this Guide. R. W. Beckwith C. G. Bickerdike P. G. Brown R. S. Coleman Y. Cote L. E. Felton Y. Fukuda G. Grinnell J. A. Meuleman W. O. Moll W. I. Pentin O. H. Smith W. A. StewartJ. Thomas A. A. Tseng E. C. Whitney The following persons were on the balloting committee that approved this document for submission to the IEEE Standards Board: M. S. Baldwin I. B. Berezowsky L. D. Boydstun S. R. Brockschink J. B. Cannon R. W. Cantrell R. L. Castleberry E. F. Chelotti R. E. Cotta P. M. Davidson D. Diamant G. Engmann D. I. Gorden R. K. Gupta J. H. Jones C. E. Kneeburg S. B. Kuznetsov P. Landrieu J. E. LeClair P. A. Lewis J. T. Madill O. S. Mazzoni D. R. McCabe G. R. Meloy M. W. Migliaro R. E. Penn@ III C. R. PopeR. J. Reiman D. E. Roberts E. P. Rothong J. E. Stoner@ Jr. T. R. Whittemore R. ZweiglerScopePurpose This guide presents descriptive material intended to assist in the planning for design@ development@ and operation of small hydroelectric power plant control systems. It does not purport to cover every possible variation that may be encountered@ but it should suf?ce to impart a working familiarity with the terminology and principles involved. Basic Definition The term "small hydroelectric power plants" does not lend itself to rigorous de?nition since small physical size is not necessarily synonymous with small (low) unit output ratings. For example@ low head installations require physically much larger turbine equipment to develop the same output as would be the case for high head installations. Small hydro (hydroelectric) power plants@ for the purposes of this guide@ have the following general attributes: Unit Ratings Output ratings are considered to range from 100 kW to approximately 5 000 kW@ and generated voltages from 480 V to 13 800 V. "Mini" or "micro" units@ as those with outputs less than 100 kW are often called@ generally have fewer control requirements. Units with outputs greater than 5 000 kW frequently require or justify more extensive control and protection than is discussed in this guide. Unit Type Small hydro turbines may be of any of the types commercially available@ including pumps operated as turbines@ but excluding reversible pump-turbines. Almost exclusively@ small hydro generators are of the alternating current type and may be either synchronous or induction type. Usually@ small hydro units are expected to require a minimum amount of field assembly and installation work@ so this would tend to rule out very slow-speed@ large-diameter units such as those with split generator stators that require final winding assembly in the field. Application Small hydro units are commonly applied in situations where associated civil construction work and costs are minimal. These applications include installations at existing dams@ pipelines@ canals@ or at new impoundment structures that can be inexpensively built. Operation and Control Almost universally@ small hydro units are provided with equipment and circuitry to enable unattended operation. Interconnection Small hydro units are generally connected to the local power company system@ and are connected either directly or through a main transformer@ frequently at a distribution substation@ or tapped into a distribution circuit. The unit may supply a portion@ or all@ of its output to a local private load@ and any surplus may be marketed to the power company. Special interconnection requirements are set by each power company to protect its equipment@ system@ and personnel. Privately owned generator installations are required to meet ANSI/NFPA 70-1987@ National Electrical Code@ Article 705@ "Interconnected Electric Power Production Sources" [1]. 1