BS EN 61173-1995 Overvoltage protection for photovoltaic (PV) power generating systems - Guide《光电功率发生系统过压保护导则》.pdf

1、BRITISH STANDARD BS EN 61173:1995 IEC 1173:1992 Overvoltage protection for photovoltaic (PV) power generating systems Guide The European Standard EN 61173:1994 has the status of a British Standard UDC 621.383:621.316.9BSEN61173:1995 This British Standard, having been prepared under the directionof t

2、he Electrotechnical Sector Board (L/1), was publishedunder the authorityofthe Standards Boardand comes into effect on 15April1995 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference EPL/47 Special announcement in BSI News November 1993 ISBN 0 580 24007X

3、Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPL/47, Semiconductors, upon which the following bodies were represented: Federation of the Electronics Industry Ministry of Defence National Supervising Inspectorate The fo

4、llowing bodies were also represented in the drafting of the standard through subcommittees: Association of Manufacturers Allied to the Electrical and Electronics Industry (BEAMA Ltd.) British Telecommunications plc Society of British Aerospace Companies Limited Amendments issued since publication Am

5、d. No. Date CommentsBSEN61173:1995 BSI 09-1999 i Contents Page Committees responsible Inside front cover National foreword ii Text of EN61173 3BSEN61173:1995 ii BSI 09-1999 National foreword This British Standard has been prepared by Technical Committee EPL/47, and is the English language version of

6、 EN61173:1994, Overvoltage protection for photovoltaic (PV) power generating systems Guide, published by the European Committee for Standardization (CENELEC). It is identical with IEC1173:1992published by the International Electrotechnical Commission (IEC). A British Standard does not purport to inc

7、lude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, page

8、s i and ii, theEN title page, pages2to8 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 61173 September 1994 UD

9、C 621.383:621.316.9 Descriptors: Photovoltaic systems, power generating, overvoltage protection, sources of overvoltages, methods to reduce overvoltages English version Overvoltage protection for photovoltaic (PV) power generating systems Guide (IEC 1173:1992) Protection contre les surtensions des s

10、ystmes photovoltaques (PV) de production dnergie Guide (CEI 1173:1992) berspannungsschutz fr photovoltaische (PV) Stromerzeugungssysteme Leitfaden (IEC 1173:1992) This European Standard was approved by CENELEC on1994-03-08. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulation

11、s which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This Eur

12、opean Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are

13、 the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de

14、 Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1994 Copyright reserved to CENELEC members Ref. No. EN 61173:1994 EEN61173:1994 2 BSI 09-1999 Foreword The CENELEC questionnaire procedure, performed for finding

15、out whether or not the International Standard IEC1173:1992could be accepted without textual changes, has shown that no common modifications were necessary for the acceptance as a European Standard. The reference document was submitted to the CENELEC members for formal vote and was approved by CENELE

16、C as EN61173on8March1994. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. Contents Page Foreword 2 Introduction 3 1 Scope and object 3 2 Normative reference 3 3 Sources of overvoltages 3 3.1 External origin

17、 of overvoltages 3 3.2 Internal origin of overvoltages 3 4 Methods to reduce overvoltages 3 4.1 Equi-potentialization (bonding) 3 4.2 Grounding 3 4.3 Shielding 4 4.4 Stroke interception 4 4.5 Protective devices 4 4.6 Principle of operation 5 Annex ZA (normative) Other internationalpublications quote

18、d in thisstandardwith the references of therelevantEuropean publications 8 Figure 1 Illustration of PVPGS grounding 5 Figure 2 Example of three common methodsusedfor PVPGS grounding 6 Figure 3 Example of no grounding 7 latest date of publication of an identical national standard (dop) 1995-03-15 lat

19、est date of withdrawal of conflicting national standards (dow) 1995-03-15EN61173:1994 BSI 09-1999 3 Introduction Protection against the consequences of overvoltages may be needed to assure safety for personnel and equipment. Proper system design requires knowledge of all components overvoltage handl

20、ing capabilities. Overvoltages stress the insulation of different system components such as phase-to-phase or phase-structure insulations. Therefore, equipment should be selected and erected so as to comply with IEC364. The system should be designed, if applicable, to provide for protection of struc

21、tures against lightning. 1 Scope and object This International Standard gives guidance on the protection of overvoltage issues for both stand-alone and grid-connected photovoltaic power generating systems. It is intended to identify sources of overvoltage hazards (including lightning) to define the

22、types of protection such as grounding, shielding, stroke interception and protective devices. NOTEThe abbreviation PVPGS is used throughout this standard for photovoltaic power generating system(s). 2 Normative reference The following normative document contains provisions which, through reference i

23、n this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying th

24、e most recent edition of the normative document indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 364, Electrical installations of buildings. 3 Sources of overvoltages Voltages greater than the maximum design voltage are considered the major h

25、azards for PVPGS. Such overvoltages can be induced by events of external origin or caused by internal malfunctions. 3.1 External origin of overvoltages In both grid-connected and stand-alone systems, the main causes of external induced overvoltages are atmospheric lightning discharges. In grid-conne

26、cted systems, voltage fluctuations (transients) in the utility line to which the PVPGS is connected can produce overvoltages within the PVPGS. In stand-alone systems, voltage fluctuations in the load can also produce overvoltages within the PVPGS. 3.2 Internal origin of overvoltages In both grid-con

27、nected and stand-alone systems, component failure, operational errors and switching transients may generate overvoltages within the PVPGS. 4 Methods to reduce overvoltages The methods used for providing an effective reduction of overvoltages are dependent on the origin of these overvoltages. 4.1 Equ

28、i-potentialisation (bonding) Bonding is used to reduce overvoltages within the PVPGS by interconnection with low impedance paths. If an earth electrode is present, it should be connected to the ground reference point. 4.2 Grounding The following paragraphs describe the appropriate grounding procedur

29、es for a PV system and the design options available to ensure maximum system safety regarding the protection of personnel and property. Figure 1 illustrates the terminology of PVPGS grounding. Figure 2 illustrates three common methods used for PVPGS grounding. Figure 3 illustrates a PVPGS without gr

30、ounding. 4.2.1 Equipment grounding Equipment grounding refers to metallic cabinets, boxes, supports and equipment enclosures which are connected to the ground reference point in order to shunt current flow to earth ground if the cabinet should become energized (come in contact with a live electrical

31、 circuit). 4.2.2 System grounding A PVPGS is system grounded if a live electrical conductor is connected to the equipment ground. System grounding may be important since it can serve to stabilize the electrical system voltage with respect to earth ground during normal system operation. It may also f

32、acilitate the operation of over-current devices in the event of a fault. Since these objectives can be obtained by other methods, system grounding may or may not be applied.EN61173:1994 4 BSI 09-1999 When system grounding is applied, one conductor of a two-wire system, or the neutral wire (center ta

33、p) of a three-wire system, should be solidly grounded in accordance with the following: a) The d.c. circuit ground connection may be made at any single point of the PV array output circuit. However, a grounding connection point placed as close to the PV modules as possible and before any other eleme

34、nts such as switches, fuses and protective diodes, will better protect the system from lightning-induced voltage surges. b) System and/or equipment grounding should not be interrupted when removing any module from the array. c) The same grounding electrode should be used for establishing the d.c. ci

35、rcuit ground and the equipment ground. Two or more electrodes that are bonded together are considered to be one electrode for this purpose. Further, this ground should be bonded to the main utility service neutral ground if present. All grounds, d.c. system and a.c. system, should be common. 4.3 Shi

36、elding Shielding provides protection from lightning striking the earth in the vicinity of the system by reducing the electromagnetic fields which interact with the system conductors. Shielding may be in the form of a conducting shell enclosing a volume, coaxial jackets or conduits through which cabl

37、es are routed, or buried bare guard wires above cables in a trench. Shielding devices shall be connected to equipment ground. Shielded volumes may be used in photovoltaic power systems when the cost of such protection is small, e.g. a grounded metal enclosure containing storage batteries or sensitiv

38、e equipment. Cable shields may also be used in photovoltaic systems for long runs of control and instrumentation cables. Without proper attention, cable shields can lose their effectiveness through cracks or breaks in the shield or by failures of the shield at the cable ends where they are connected

39、 to the ground system. These shield-to-ground connections are especially susceptible to corrosion and the effects of mechanical motion and stress. An alternative method for shielding d.c. power cables which are not contained in metal conduits is the use of guard or screen wires above the cable trenc

40、hes. 4.4 Stroke interception Interception can be achieved through the use of grounded vertical masts (lightning rods or air terminals) and/or elevated ground wires. The following topics should be addressed in determining the necessity of stroke interception hardware: personnel safety (manned or unat

41、tended site); the operational effects of a direct hit on the system (e.g. probability of complete loss of battery storage); the cost of the interception hardware versus the probability of a direct hit and the replacement cost of damaged elements; loss of system performance due to shadowing. 4.5 Prot

42、ective devices Protective devices PDS should be used to provide overvoltage protection for sensitive equipment such as power conditioners or other components. For effective system protection, these devices should satisfy the following criteria: PDs shall not degrade beyond their minimal characterist

43、ics over their design life, even under extreme operating conditions; they shall limit the voltage at the protected terminals to a safe level; they should not fail under the expected transients; in some cases, they should safely conduct overcurrents until upline protection (e.g.contactors or fuses) b

44、ecomes effective; they should not degrade beyond their design life even under extreme operating conditions of the system; they should not degrade normal system performance over the system design life; they should have minimal impact on system efficiency. The main types of protective devices used for

45、 protection of electronic equipment are: diodes; varistors; spark gap devices and gas discharge fuses; isolation transformers; filters; optocouplers.EN61173:1994 BSI 09-1999 5 4.6 Principle of operation The basic concept of overvoltage reduction by means of a protective device consists of shunting t

46、he terminals to be protected by a nonlinear circuit element which changes to a low resistance state if the safety limits of the voltage are exceeded. As a result, the residual overvoltage present on the protected part is a small fraction of the original overvoltage. The value of this fraction is giv

47、en by the ratio of the residual resistance of the protective device to the characteristic impedance of the line at the frequencies which form the transient. Figure 1 Illustration of PVPGS groundingEN61173:1994 6 BSI 09-1999 Figure 2 Example of three common methods used for PVPGS groundingEN61173:199

48、4 BSI 09-1999 7 Figure 3 Example of no groundingEN61173:1994 8 BSI 09-1999 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications This European Standard incorporates by dated or undated reference, provisions from other

49、publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. NOTEWhen the international publication has been modified by CENELEC common modifications, indicated by (mod), the relevan