1、CENELEC ENxbL173 94 W 3404583 0353764 2T3 BRITISH STANDARD BS EN 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 : 621.316.9 61173 : 1995 iEC 1173 : 1992 CENELEC ENxbLL73 94 3404583 O
2、L537b5 L3T BS EN 61173 : 1995 Amd. No. The following BSI references relate to the work on this standard: Committee reference EPLi47 Committees responsible for this British Standard Date lxt affected The preparation of this British Standard was entrusted to Technical Committee EPL/47, Semiconductors,
3、 upon which the following bodies were represented: Federation of the Electronics Industry Ministry of Defence National Supervising Inspectorate The following bodies were also represented in the drafting of the standard through subcommittees: Association of Manufacturers Allied to the Electrical and
4、Electronics Industry British Rlecommunications plc Society of British Aerospace Companies Limited (BEAMA Ltd.) This British Standard, having been prepared under the direction of the Electrotechnical Sector Board (Ll), was published under the authority of the Standards Board and comes into effect on
5、15 April 1995 O BSI 1995 Amendments issued since publication Special announcement in BSI Naus November 1993 ISBN O 680 24007 X CENELEC EN*b1173 94 = 3404583 0353766 076 BS EN 61173 : 1995 National foreword This British Standard has been prepared by Rchnical Committee EPL/47, and is the English langu
6、age version of EN 61173 : 1994, Overvoltugeprotection for photovoltaic (PV) power generating systems - Guide, published by the European Committee for Standardization (CENELEC). It is identical with IEC 1173 : 1992 published by the International Electrotechnical Commission (IEC). Compliance with a Br
7、itish Standard does not of itself confer immunity from legal obligations. i CENELEC EN*bLL73 94 3404583 O353767 TO2 = EUROPEAN STANDARD EN 61173 NORME EUROPENNE EUROPISCHE NORM September 1994 UDC 621.383 : 621.316.9 Descriptors: Photovoltaic systems, power generating, overvoltage protection, sources
8、 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 systmes photovoltaques (PV) de production d?nergie - Guide Leitfaden (CE1 1?73 : 1992) berspannun
9、gsschutz fr photovoltaische (PV) Stromerzeugungssysteme (IEC 1173 : 1992) This European Standard was approved by CENELEC on 1994-03-08. CENELEC members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a nation
10、al standard without any alteration. Up-to-date lists and bibiiographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in
11、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 the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France,
12、Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central
13、 Secretariat: rue de Stassart 35, B-1050 Brussels O 1994 Copyright reserved to CENELEC members Ref. No. EN 61173 : 1994 E CENELEC ENub3373 94 m 3404583 0353768 949 m Page 2 EN 61173 : 1994 Foreword The CENELEC questionnaire procedure, performed for finding out whether or not the International Standa
14、rd IEC 1173 : 1992 could 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 CENELEC as EN 61173 on 8 March 1994. The foll
15、owing dates were fixed: - latest date of publication of an identical national standard (dop) 1995-03-15 - latest date of withdrawal of conflicting national standards (dow) 1995-03-15 Annexes designated normative are part of the body of the standard. In this standard, annex ZA is normative. CENELEC E
16、N*bLL73 94 3404583 0153769 885 Page 3 EN 61173 : 1994 CONTENTS INTRODUCTION . 4 Clause 1 Scope and object . 5 2 Normative reference 5 3 Sources of overvoltages 5 ,3.1 External origin of overvoltages . 5 3.2 Internal origin of overvoltages 5 Methods to reduce overvoltages 6 4.1 Equi-potentialization
17、(bonding) 6 4.2 Grounding . 6 4.3 Shielding . 7 4.4 Stroke interception 7 4.5 Protective devices . 8 4.6 Principle of operation 8 Figures 9 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications . 11 4 CENELEC ENab3373
18、94 3404583 0353770 5T7 D Page 4 EN 61173 : 1994 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 handling capabilities. Overvoltages stress the insulation
19、 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 IEC 364. The system should be designed, if applicable, to provide for protection of structures against lightning. CENELEC ENrbLL73 94 340458
20、3 OL5377L 433 = Page 5 EN 61173 : 1994 OVERVOLTAGE PROTECTION FOR PHOTOVOLTAIC (PV) POWER GENERATING SYSTEMS - GUIDE 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
21、 is intended to identify sources of overvoltage hazards (including lightning) to define the types of protection such as grounding, shielding, stroke interception and protective devices. NOTE - The abbreviation PVPGS is used throughout this standard for photovoltaic power generating system( s). 2 Nor
22、mative reference The following normative document contains provisions which, through reference in 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 b
23、ased on this .,iternational Standard are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. I EC 364: Electrical installations of buildings. 3 S
24、ources of overvoltages Voltages greater than the maximum design voltage are considered the major hazards 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, th
25、e main causes of external induced overvoltages are atmospheric lightning discharges. In grid-connected systems, voltage fluctuations (transients) in the utility tine to which the PVPGS is connected can produce overvoltages within the PVPGS. In stand-alone systems, voltage fluctuations in the load ca
26、n also produce overvoltages within the PVPGS. 3.2 Internal origin of overvoltages In both grid-connected and stand-alone systems, component failure, operational errors and switching transients may generate overvoltages within the PVPGS. CENELEC EN*bL373 911 M 31104583 0353772 37T Page 6 EN 61173 : 1
27、994 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 qui-potentialisatioB (bonding) Bonding is used to reduce overvoltages within the PVPGS by interconnection with low impedance paths. If an
28、earth electrode is present, it should be connected to the ground reference point. 4.2 Grounding The following paragraphs describe the appropriate grounding procedures for a PV system and the design options available to ensure maximum system safety regarding the protection of personnel and property.
29、Figure 1 illustrates the terminology of PVPGS grounding . Figure 2 illustrates three common methods used for PVPGS grounding. Figure 3 illustrates a PVPGS without grounding. 4.2.1 Equipment grounding Equipment grounding refers to metallic cabinets, boxes, supports and equipment enclosures which are
30、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 circuit). 4.2.2 System grounding A PVPGS is system grounded if a live electrical conductor is connected to the equipment ground. Syste
31、m 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 facilitate the operation of over-current devices in the event of a fault. Since these objectives can be obtained by other methods, syste
32、m grounding may or may not be applied. When system grounding is applied, one conductor of a two-wire system, or the neutral wire (center tap) 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
33、the PV array output circuit. However, a grounding connection point placed as close to the PV modules as possible and before any other elements such as switches, fuses and protective diodes, will better protect the system from lightning-induced voltage surges. b) System and/or equipment grounding sho
34、uld not be interrupted when removing any module from the array. CENELEC EN*bLL73 94 m 3404583 0353773 206 m Page 7 EN 61173 : 1994 c) The same grounding electrode should be used for establishing the d.c. circuit ground and the equipment ground. Two or more electrodes that are bonded together are con
35、sidered 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 Shielding Shielding provides protection from lightning striking the earth in the vicinity of the
36、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 cables are routed, or buried bare guard wires above cables in a trench. Shielding devices shall be
37、 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 sensitive equipment. Cable shields may also be used in photovoltaic systems for long runs of control a
38、nd 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 to the ground system. These shield-to-ground connections are especially susceptible to corros
39、ion 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 trenches. 4.4 Stroke interception Interception can be achieved through the use of grounded vertical
40、 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 unattended site); - the operational effects of a direct hit on the system (e.g. probability of c
41、omplete 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. CENELEC ENxb3373 94 3404583 O353774 142 Page 8 EN 61173 : 1994 4.5 Protective devices Protecti
42、ve 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 characteristics over their design
43、 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.9. contactors or fuses) becomes effect iv
44、e; - 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 protecti
45、on of electronic equipment are: - diodes; - varistors; - spark gap devices and gas discharge fuses; - isolation transformers; - filters; - optocouplers. 4.6 Principle of operation The basic concept of overvoltage reduction by means of a protective device consists of shunting the terminais to be prot
46、ected 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 given by the ratio of the
47、residual resistance of the protective device to the characteristic impedance of the line at the frequencies which form the transient. CENELEC EN+bLL73 74 = 3404583 0553775 087 = Page 9 EN 61173 : 1994 Array field 1 I O To be connected to PVPGS the load in accordance electronics with local codes and
48、- standards 1 n System grounding conductor Equipment ground Ground reference point Figure 1 - Illustration of PVPGS grounding CENELEC ENUbLL3 94 m 3404583 0153776 TL5 m PVPGS electronics Page 10 EN 61173 : 1994 O Load or grid o Equipment ground System common ground and equipment grounding System cen
49、tre tap and equipment grounding PVPGS electronics Load or grid I I -o To be connected to the load in accordance with local codes and standards - - PVPGS electronics J PVPGS Load or grid O A c I I 1- To be connected to - the load in accordance with local codes and standards Figure 2 - Example of three common methods used for PVPGS grounding Figure 3 - Example of no grounding CENELEC EN*b1173 94 3404583 0153777 951 Page 11 EN 61173 : 1994 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European pub
