Frankfurt (Germany), 6-9 June 2011 EN voltage dips and swells classification as an instrument for responsibility sharing Maurizio Delfanti Department of Energy– Politecnico di Milano CENELEC TC 8X/WG1 Secretary

Frankfurt (Germany), 6-9 June 2011 TC8X Organization TC8X System Aspects of Electricity Supply WG 1 Physical Characteristics Of Electrical Energy WG 3 Requirements for connection of generators to distribution networks WG 4 Endorsement Of IEC as European Standard TF WG 5 Smart Grid Requirements

Frankfurt (Germany), 6-9 June 2011  First edition: November 1994 EN 50160: Voltage characteristics of electricity supplied by public distribution systems. Subjects: LV and MV distribution networks  Further Editions: 1999, 2007  Current Edition: EN 50160:2010 prEN 50160:2009 voted positively on May, 2009 Ratification postponed by CLC BT due to comments received Finally ratified by BT on March 2010 and dispatched on July 2010 Corrigendum December 2010 (d.o.w. of conflicting std  ) Implemented at national level by March,1 st Editions of EN 50160

Frankfurt (Germany), 6-9 June 2011  This European Standard defines, describes and specifies the main characteristics of the voltage at a network user's supply terminals in public low, medium and high voltage electricity networks under normal operating conditions.  This standard describes the limits or values within which the voltage characteristics can be expected to remain at any supply terminal in public European electricity networks and does not describe the average situation usually experienced by an individual network user. 4 EN 50160:2010 new title and scope Voltage characteristics of electricity supplied by public distribution systems electricity networks

Frankfurt (Germany), 6-9 June 2011 In the new edition (EN 50160:2010), a distinction is made between:  continuous phenomena, i.e. small deviations from the nominal value that occur continuously over time - such phenomena are mainly due to load pattern, changes of load or nonlinear loads;  voltage events, sudden and significant deviations from normal or desired wave shape. Voltage events are typically due to unpredictable events (e.g., faults) or to external causes (e.g., weather, third party actions) For some continuous phenomena limits are specified; for voltage events, only indicative values can be given at present. 5 New edition (EN 50160:2010) continuous phenomena / voltage events

Frankfurt (Germany), 6-9 June 2011 Voltage events, sudden and significant deviations from normal or desired wave shape.  Interruptions of the supply voltage  Supply voltage dips/swells  Transient overvoltages between live conductors and earth It is possible to give only indicative values (incl. RVCs): such phenomena are difficult to predict; more investigation is needed 6 Voltage events

Frankfurt (Germany), 6-9 June 2011 Definition: a temporary reduction of the voltage at a point in the electrical supply system below a specified start threshold. Note 1: For the purpose of this standard, the dip start threshold is equal to 90 % of the reference voltage. Note 2: Typically, a dip is associated with the occurrence and termination of a short circuit or other extreme current increase on the system or installations connected to it. Note 3: For the purpose of this standard, a voltage dip is a two dimensional electromagnetic disturbance, the level of which is determined by both voltage and time (duration). 7 Voltage events: voltage dips

Frankfurt (Germany), 6-9 June 2011  Reference was made to test levels given in EN (different test levels for different classes: 1, 2, 3, X)  EN contains a reference to the “network performance” 8 Network performance & equipment test levels Test levels for appliances in EN , class 3  It is useful to describe the possible behavior of the network with the same parameters used for testing appliances (Product Standards)

Frankfurt (Germany), 6-9 June 2011  Measurement uncertainty (addressed in EN ) has to be considered.  The duration of a voltage dip depends on the protection strategy adopted, which may differ from case to case (network structure, neutral earthing, etc)  Durations do not necessarily match the boundaries of the columns of the Table. 9 The new classification in EN 50160:2010, Tables 2, 5 and 8

Frankfurt (Germany), 6-9 June 2011 For a given class of appliances (f.i., class 3), the cells above the curve represent an immunity area Classes are referred to different electromagnetic environment, as defined in EN Duration t [ms] Range of res. voltage Ur (in % of Un or Ud)10 < t ≤ < t ≤ < t ≤ > Ur ≥ 80 A1A2A3+A4 80 > Ur ≥ 70 B1B2B3+B4 70 > Ur ≥ 40 C1C2C3+C4 40 > Ur ≥ 5 D1D2D3+D4 10 Equipment immunity

Frankfurt (Germany), 6-9 June 2011 For the cells below the curve, a regulation can be enforced at a national level Expected values (for each bus? for each area? for worst served customers?) can be given by TSO/DSO 11 Duration t [ms] Range of res. voltage Ur (in % of Un or Ud) 10 < t ≤ < t ≤ < t ≤ > Ur ≥ 80 A1A2A3+A4 80 > Ur ≥ 70 B1B2B3+B4 70 > Ur ≥ 40 C1C2C3+C4 40 > Ur ≥ 5 D1D2D3+D4 Voltage quality requirements

Frankfurt (Germany), 6-9 June 2011  As some standard/national documents (France, South Africa) already foresee, it is useful to set a bound between:  events for which appliances have to be immune  events that can be limited by the DSO/TSO  The concept of a “responsibility sharing curve” is much wider and complex (see next presentation by M. Bollen)  In the new edition of the Standard (EN 50160:2010) the concept has been applied to voltage dips 12 Responsibility sharing curve

Frankfurt (Germany), 6-9 June 2011 This annex is aimed at providing the reader with some information about indicative values currently available at a European level for some of the events defined and described in the standard. Some information is also given about the way of using values given in the standard, and about the way of collecting further measurement data, in order to allow for comparisons between different systems and to have homogeneous data at a EU level. As many monitoring systems are in place in some countries, further information is available at a national level. At a national level, more precise figures can be found; furthermore, some regulations may exist. 13 Annex B: B.1 General

Frankfurt (Germany), 6-9 June 2011 QuEEN monitors about 10% of the main MV bus-bars. The sample is representative of the network characteristics in terms of:  number of HV/MV substations per region  length of the MV lines  type of MV lines: cable, overhead, mixed  neutral compensation or isolated neutral  number/density of MV/LV customers The system is managed by RSE (Ricerca sul Sistema Energetico) QuEEN: 400 monitoring units installed on MV bus-bars of HV/MV substations

Frankfurt (Germany), 6-9 June 2011 QuEEN report, year 2008 (data collected on 10% of MV main busbars)  Average number of dips per bus: 124,1  97,7 voltage dips would be overcome by class 3 equipment  26,4 voltage dips would impair the operation of class 3 equipment Duration t [ms] Range of res. voltage Ur (in % of Un or Ud) 10 < t ≤ < t ≤ < t ≤ > Ur ≥ 80 29,2 5,6 2,0 80 > Ur ≥ 70 18,6 4,3 0,6 70 > Ur ≥ 40 40,0 6,8 0,7 40 > Ur ≥ 5 15,4 2,6 0,3

Frankfurt (Germany), 6-9 June 2011 QuEEN report, year 2009 (data collected on 10% of MV main busbars)  Average number of dips per bus: 114,2  95,6 voltage dips would be overcome by class 3 equipment  18,6 voltage dips would impair the operation of class 3 equipment Duration t [ms] Range of res. voltage Ur (in % of Un or Ud) 10 < t ≤ < t ≤ < t ≤ > Ur ≥ 80 34,97,5 2,6 80 > Ur ≥ 70 17,15,3 0,8 70 > Ur ≥ 40 28,25,3 0,7 40 > Ur ≥ 5 9,91,7 0,2

Frankfurt (Germany), 6-9 June 2011 QuEEN report, year 2010 (data collected on 10% of MV main busbars)  Average number of dips per bus: 98,3  82,4 voltage dips would be overcome by class 3 equipment  15,9 voltage dips would impair the operation of class 3 equipment Duration t [ms] Range of res. voltage Ur (in % of Un or Ud) 10 < t ≤ < t ≤ < t ≤ > Ur ≥ 80 31,56,4 2,0 80 > Ur ≥ 70 15,54,4 0,6 70 > Ur ≥ 40 22,64,8 0,5 40 > Ur ≥ 5 8,51,3 0,2

Frankfurt (Germany), 6-9 June 2011 Towards VQ regulation in Italy Based on the EN 50160:2010, on the data collected by QuEEN, and on an economic analysis of the impact of microinterruptions (transient interruptions+voltage dips, PoliMI – DIG 2006) on the Italian economy, Autorità per l’energia elettrica e il gas published two Consultation Documents (DCO 42/10; DCO 15/11); some proposals regard: 1) extension of VQ monitoring to all MV busbars of HV/MV stations (about 4000 VQ meters needed) 2) publication of expected/registered values of microinterruptions (transient interruptions+voltage dips) by the DSO for each MV main busbar (publication of long and short interruptions already in force) The availability of such data would allow a sensitive user to evaluate on a sound technical base if further immunization / mitigation is needed for his specific production process (equipment class; UPS; PQ contract).

Frankfurt (Germany), 6-9 June 2011 THANK YOU! Maurizio Delfanti – Italy – RT 2a