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DER Technical Forum

DER Technical Forum. DER Technical Forum 16 April 2019 10:30 at ENA. For those dialling in: 0208 322 2794 PIN: 3352770#. Welcome, Housekeeping, Introductions. Todays Agenda. Minutes of previous meeting and actions.

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DER Technical Forum

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  1. DER Technical Forum DER Technical Forum 16 April 2019 10:30 at ENA For those dialling in: 0208 322 2794 PIN: 3352770#

  2. Welcome, Housekeeping, Introductions

  3. Todays Agenda

  4. Minutes of previous meeting and actions • Accept, together with slides and running list of issues, as correct record of the meeting. • Matters arising not on the agenda: • None?

  5. New Issue 1 Q52 6.3.7 states that: “this document includes the requirement to submit validated detailed models in respect of asynchronous Power Generating Modules…” and 6.3.8 that “where the DNO deems is necessary to ensure…validated models…are required…”. Are validated simulation models required in every case or only when requested by the DNO? These clauses might need to be reworded accordingly. A The underlying RfG requirement in Art 43.3 is that all models are validated - so we can probably amend these paragraphs to reflect that in due course The stakeholder who raised the issue is content with the answer above

  6. New Issue 2 Q53 11.1.6 states that: “As part of the connection application process the Generator shall agree with the DNO the set points of the control scheme for voltage control, Power Factor control or Reactive Power control as appropriate”. However, there is no requirement that for Type A voltage control and/or power factor control and/or reactive power control are/is needed. Please clarify this clause; the “as appropriate” should refer to whether any of these controls are needed. A There is a requirement for Type A in GB– it is 11.1.6. You are correct that there is nothing in RfG, but this is a pre-existing national requirement that the reactive output will be managed – usually by PF control, although it was always the DNOs’ discretion to agree other arrangements with Generators. Q My [GB] experience so far has been that most connection offers I have reviewed (and these were plenty - with the exception of one DNO that requires voltage control, another that has had voltage control requirements magically appear in the connection agreement but there were almost never provided in the connection offer stage, and most recently another one that required kind of a power factor control but written in conditions that were contradicting one another) never mention power factor control as a requirement, rather the capability to operate within a certain power factor range. This is the reason why I was surprised to see the requirement for power factor/reactive power/voltage control appear in EREC G99 but “hidden” in a different requirement, as extra equipment would need to be procured and placed ideally at the Connection Point

  7. New Issue 3 Q54 In general on the LFSM-O (d) Does this clause mean that above 50.9Hz the active power reduction is no longer a function of the frequency, in other words above 50.9Hz is active power reduced by at least 0.5%/s for as long as the frequency is above 50.9Hz? Also, what does “initial output” refer to? A No. It is saying that above this rate the droop must be achieved at this rate of change. We suggest you review the GC0110 papers that explain this – although reviewing the text and graphs in A7.2.4 will probably be helpful too. Initial output is the power output at the time of the frequency excursion – which of course might be anywhere between minimum stable operation and registered capacity. It might be appropriate to make the speed of response element more clear in the requirements in Section 11 and 12 of G99 in a future revision. On this basis the stakeholder who raised the issue is content with the answer above

  8. New Issue 4 Q55 12.3.1.1 and 12.3.1.2: Could you please confirm then that Figure 4 represents both the minimum voltage/time profile AND the lower limit of actual course of the phase-phase voltages? A No – it only represents the former. The latter is not generically specified. Q The difference is whether this is the actual voltage profile the PPM should withstand (therefore this exact voltage trace will need to be either applied at the terminals or simulated – regardless of the fact that this voltage trace will almost never be experienced in reality, as voltage recovery is rather transient and does not follow such smooth ramps) or whether the PPM should withstand voltage depressions of a retained voltage given on the y axis and time given on the x axis (e.g. on figure 12.4, withstand a retained voltage of 85% for at least 180 seconds).

  9. New Issue 5 Q56 12.4.3.2 and 12.4.3.3: It is unclear if one of these control modes (voltage control or reactive power control or power factor control) is mandatory and if the items that need to be agreed with the DNO are which of these control modes should be applied and the associated setpoints. A The voltage control mode will be agreed between the DNO and Generator, and so will any parameters that are needed. Mandatory might not be the right word – but we do not believe there are any other practical options for the management of reactive output other than these three control modes, so one must be selected, along with appropriate parameters. Q This is another instance of the same issue, ie whether some sort of reactive power management is introduced through the G99. So long as the DNOs are aware of this requirement and specify this in the connection offer, and it is really needed by them, I am happy with this clause, however for clarity, there should be a clause stating that these control modes are indeed required!

  10. New Issue 6 Q57 12.5.1: For which voltage levels should the PGM supply this capability? Only at nominal voltage? Please clarify. A At nominal voltage This should probably be specified more clearly in a future update to G99. On this basis the stakeholder who raised the issue is content with the answer above

  11. New Issue 7 Q58 12.6 (respectively 13.3): I find this clause is in general confusing and needs to be redrafted entirely to provide clarity about what exactly is requested re. FFCI. Will you be implementing changes to the definitions as per GC0111 in the next revision? If so, my comments below might not be relevant any longer. A The FFCI revised text will be out for consultation probably in early April – it has been revised mainly because of the sorts of deficiencies you have pointed out. The stakeholder who raised the issue is content with the answer above

  12. New Issue 8 Q59 13.2.4: For LFSM-O, Type B had the requirement that “for deviations in frequency beyond 50.9 Hz the measured rate of change of Active Power reduction shall exceed 0.5% s-1 of the initial output” which however does not appear for Type C/D PFM, is that intentional? A Intentional because the tests for FSM pick up this functionality. The stakeholder who raised the issue is content with the answer above

  13. New Issue 8 continued Q60 17.4.1: Are all of the items (a) – (e) needed or any of them or a certain combination of some of them? Please clarify and amend the clause to reflect what is required. A All The stakeholder who raised the issue is content with the answer above

  14. New Issue 9 Q61 21.1.1: “Manufacturers’ Information covers such information as type testing details, parameters or data, simulation models and reports on studies run using those models.” If so, then all the forms (e.g. B2-1) that contain both MI and TV should include either MI or TV, but not both because it can be confusing. As a general comment, such forms, albeit useful, make it very hard to properly define our scope for each project; how should we interpret the “key to submission stage” in conjunction with the “key to the evidence requested”? For instance, interface protection on page 282: which of the MI, TV, T items are requested at IS and which are requested at FONS stage? Are all are all of MI, TV, T items needed or some of them or only one of them or a particular combination of them? A DNOs are not specifying how the Generator (and manufacturer) will prove compliance - that is the Generator’s responsibility. All we are doing here is setting the DNOs’ expectations as to what are the possible sources of confirmation of compliance – hence the title for the fourth column in B2-1 includes “(and / or)” to signify the choices that the Generator can make in selecting how compliance is demonstrated. This column is really for guidance and helping the Generator to explain what information he is submitting.

  15. New Issue 10 Q62 Form B2-1 Part 2 (C2-1 Part 2 respectively), in the text field below reactive power capability, it is written that “confirm compliance with Section 12.5 by carrying out simulation study in accordance with B.4.2 and by submission of a report”, but in the evidence requested there is also D and TV, are these also compliance options? A That is a valid point and we agree that MI was drafted to include S. However as you say for Type B and certainly Type C this is more likely to be a site specific study – so and S here would be appropriate. We will add it at the next opportunity. The stakeholder who raised the issue is content with the answer above

  16. New Issue 11 Q63 Form B2-1 Part 2 (C2-1 Part 2 respectively), in the text field below reactive power capability, it is written that “confirm compliance with Section 12.5 by carrying out simulation study in accordance with B.4.2 and by submission of a report”, but in the evidence requested there is also D and TV, are these also compliance options? A That seems a good point – we should probably remove the D and T at the next opportunity The stakeholder who raised the issue is content with the answer above

  17. New Issue 12 Q64 B.4.1.1: “The studies specified in this Annex will normally be sufficient to demonstrate compliance”. Does this mean that the study under B.4.2 corresponds to item S under e.g. reactive power capability on page 285, making this item alone sufficient? But then B.4.2.1 says that “IF specified by the DNO, the generator shall supply simulation studies…”. How to interpret this? The same applies to the respective clauses of Section C7.1. A Yes, the B.4.2 studies are those required to demonstrate compliance with paragraph 12.5 as recorded in the PGMD. The drafting of B.4.2.1 allows for the option in B4.1.1 for the Generator to agree alternative compliance studies.

  18. New Issue 13 Q65 B.6.1.2 (a): Is this supposed to read “Manufacturer’s Data and Performance Report”? A This is a typo and the whole term should be made bold to indicate the definition being used. The stakeholder who raised the issue is content with the answer above

  19. New Issue 14 Q66 C.5.6 and C.5.7 refer to the Grid Code, although 13.4.5 states that “as part of the connection application process the Generator shall agree with the DNO the set points of the control scheme for voltage control, Power Factor control or Reactive Power control as appropriate”. Please align these clauses. A Yes- these only apply where the installation is also caught by the Grid Code. We can make this clearer in C5. 13.4.5 remains correct in all cases. The stakeholder who raised the issue is content with the answer above

  20. New Issue 15 Q67 C.7.6.6: Does this clause mean that Figure C.9.3 will be applied as a test as part of the simulations or as part of compliance testing or both? Is C.8.6 applicable as a whole? A This paragraph requires the simulation models to be validated against the actual test results.

  21. New Issue 16 Q68 C.10.1.3: does this commercial contract have a title? Is it the Mandatory Services Agreement? A It is not appropriate to include any details of NGESO’s commercial arrangements in a DNO document. The stakeholder who raised the issue is content with the answer above

  22. New Issue 17 Q69 Further to our discussions regarding the introduction of the new standard and the project we are currently involved in I attach a copy of the document received from the specialist supplier of the CHP equipment. The proposed unit is of 15kW capacity ,is 3 phase, and will be operated on a heat lead regime so will only be operating intermittently. The CHP installation has been in the planning process for at least 18 months. I have read what I believe to be relevant clause of the new standard (11.1.5) to which the attached correspondence refers, and I am not sure that the suppliers are correctly interpreting the intent of the standard. My understanding of this clause is that the equipment shall be capable of delivering its full/rated output at power factors between 0.95 lagging and 0.95 leading. From the attached correspondence they appear to be trying to correct the power factor to within this range. A In theory yes. However DNOs believe that equipment that meets the requirements of Annex C6 is available on the market, so if this is correct it would be impossible to get a derogation.

  23. New Issue 18 Q70 We have been advised that for our Asynchronous CHP units, that the Power Factor statement as per section 9.5.1 for G98 and section 11.1.5 for G99 apply to our units. If you can please advise if this is required for our CHPs units or not? If this is required, please can you provide a statement we can forward to our customers. I was also hoping to ask about the using a site wide Power Factor and is this acceptable to use for generation or not? All our units are all under Type A, even combining/using multiple of our units, we still come under Type A for G99. A Same as Q69 above.

  24. Question 32 It is unclear how the voltage fluctuation requirement on tripping as required in A2-1 is compatible with other voltage requirements in G99, Nigel Smith - Sustainable control Systems Ltd. The power quality aspects in G99 are essentially the same as G59. Both documents require compliance with P28 - Planning Limits for Voltage Fluctuations Caused by Industrial, commercial and Domestic Equipment in the United Kingdom. Many of the references in P28 are out of date and a new version has been through two public consultations. The new version P28/2 is expected to be issued shortly.

  25. Question 32 Form A2-1 Form A2-1 is applicable to Power Generating Modules rated up to 50kW (i.e. 72.46A per phase). The voltage fluctuation requirements in A2-1 (and also the Type Test Sheet in 13.1 of G59/3-4) are based on compliance with BS EN 61000-3-11 which is applicable to equipment with rated current ≤ 75 A and subject to conditional connection. The following limits are specified in G99 and G59. These are in line with BS EN 61000-3-11 : • dmax(max. absolute voltage change) = 4% • dc (max. steady state voltage change)= 3.3% • Pst(short term flicker severity) = 1.0 • Plt (long term flicker severity) = 0.65

  26. Question 32 Under BS EN 61000-3-11 the manufacturer must make one of the following statements in the instruction manual, relating to voltage fluctuations: • The equipment complies with the requirements of IEC 61000-3-3 • The equipment is intended for use only in premises having a service current capacity ≥ 100A • The maximum permissible system impedance (Zmax) at the interface point of the user’s supply is ….. “The equipment complies with the requirements of IEC 61000-3-3” If this statement is made the equipment meets the voltage fluctuation limits when tested with the standard system reference impedance (Zref) that is used for equipment rated up to 16A per phase (in BS EN 61000-3-3). This reference impedance is 0.24 + j0.15 ohms for the phases and 0.16 + j0.1 ohms for the neutral. In this case the connection is unconditional

  27. Question 32 “The equipment is intended for use only in premises having a service current capacity ≥ 100A” In this case the equipment meets the voltage fluctuation limits when tested with the standard test impedance (Ztest) applicable to equipment rated up to 75A per phase. This reference impedance is 0.15 + j0.15 ohms for the phases and 0.1 + j0.1 ohms for the neutral. If this statement is made the connection is conditional upon the Connection Point having an impedance ≤ Zref “The maximum permissible system impedance (Zmax) at the interface point of the user’s supply is …..” In this case the equipment only meets the voltage fluctuation limits when the impedance is Zmaxor less. If this statement is made the connection is conditional upon the Connection Point having an impedance ≤ Zmax

  28. Question 32 Further Discussion Nigel Smith was concerned that it would not be possible to meet the requirements of BS EN 61000-3-11 for a sudden disconnection of a 50kW Power Generating Module and questioned whether this was a credible condition. A sudden loss of generation could occur if the G99 interface protection trips. Interface protection cannot distinguish between local faults and faults / issues on the wider network and so this protection is likely to operate on occasions. This condition is considered credible in the latest draft of P28/2 (clause 4.7). Example: A sudden change of 50kW (i.e. 72.46A) would cause a step voltage change of up to 26.9V (11.7%) if Zref is used and a voltage change of up to 15.4V (6.7%) if Ztest is used, exceeding the limit for dc (i.e. 3.3%). In order to satisfy the limit the manufacturer would have to declare a Zmaxvalue of 0.105 ohms, if the most onerous power factor is assumed.

  29. Question 32 Further Discussion (continued) I have also had discussions with both Nigel Smith and Dick Allen (British Hydro Association) relating to the impact of magnetising inrush when energising transformers. This inrush current is transient in nature and causes a short dip in the voltage which then recovers to a steady state value. This transient voltage change is not explicitly covered in the current version of P28 . WPD have allowed transient voltage dips below the 3% step change in voltage limit specified in P28, e.g. 6% or 10%, depending on the expected frequency of those events. The draft version of P28/2 addresses this issue and allows transient voltage dips of up to 6% for frequent events, 10% for infrequent events (up to 4 events in 1 month) and 12% for very infrequent events (up to 1 event in 3 months). Each event may consist of up to 4 rapid voltage changes (RVCs) separated by at least 10 minutes but completed within 2 hours. This could, for example, allow for up to 4 transformers, to be energised one at a time.

  30. Question 32 Further Discussion (continued) Nigel Smith and Dick Allen also mentioned that clause 9.5.7 G59/3-4 includes the following statement: Typical limits for Step Voltage Change caused by the connection and disconnection of any Customers equipment to the Distribution System should be ± 3% for infrequent planned switching events or outages in accordance with EREC P28. For unplanned outages such faults it will generally be acceptable to design to a Step Voltage Change of ±10%. The Distribution Code makes allowances for these events in DPC4. A step change in voltage of 10% is high enough to cause G59 and G99 protection to operate which could put the security and stability of the network, including the transmission network, at risk. It could also cause significant issues for customer equipment and associated processes. If the group decide to add this statement to G99 and/or P28/2 then I believe this would require both a Distribution Code and Grid Code consultation.

  31. Question 38 Page 199 in G99 (consultation 3?), requirement for transformer for "Power Quality" improvement. Is this an isolation transformer? And if so, can this be clearer in documentation? G99 Issue 1 Amendment 3 Compliance Form A2-1 (page 193), Compliance Form A2-2 (page 203)  and Compliance Form A2-3 (page 209) each include the statement: “Power Generating Modules with emissions close to the limits laid down in BS EN 61000-3-12 may require the installation of a transformer between 2 and 4 times the rating of the Power Generating Module in order to accept the connection to a Distribution Network”. The statement is also included within clause 9.4.3.2..

  32. Question 38 This paragraph is simply saying that the DNO may have to install a larger distribution transformer (e.g. 11kV / LV transformer)  than normal in order to provide a low enough network impedance to ensure the voltage distortion (harmonics) on the DNO network remain within the Planning Limits. It is not referring to a Generator provided isolation transformer, although an isolation transformer may be needed for inverter connected Generating Units to prevent d.c. injection into the DNO network, in accordance with 9.4.6.2. This statement could be removed from Form A2-1, A2-2 and A2-3 as this is a network design issue rather than a specific Power Generating Module compliance issue, although clearly the DNOs network impedance does influence power quality compliance.

  33. Question 38 Background BS EN 61000-3-12 specifies the Limits for harmonic currents produced by equipment connected to public low-voltage systems with input current > 16 A and ≤ 75 A per phase. Under this standard the manufacturer defines the minimum Short Circuit Power level that is required at the interface point between the user's supply and the public, known as the point of common coupling, in order for the voltage distortion (i.e. harmonics) to meet the required limits. This Short Circuit Power requirement is expressed as the RSCE (Short Circuit Ratio) of the equipment. The standard value that is applicable to the majority of equipment is RSCE = 33 although alternative values may be specified by the manufacturer, where needed. Where RSCE = 33 is specified the required Short Circuit Power level for a 3 phase item of equipment is 33x its power rating.

  34. Question 38 Example: A 3 phase 230/400V 50kVA generator with an RSCE of 33 would need to be connected to a network with Short Circuit Power level (at the point of common coupling) of at least 33 x 50 = 1650kVA. The Short Circuit Power defines the amount of power than would flow if a 3 phase short circuit fault were to occur at that position on the network. The lower the impedance of the network, the more power that would flow. In this context the Short Circuit Power is simply a convoluted way of defining the maximum network impedance that is allowed at the point of common coupling. In this example, the maximum network phase impedance at the point of common coupling would be = (√3x230)2 / (1650 x 1000) =  0.0962 ohms

  35. Unresolved Previous Issues - 1

  36. Unresolved Previous Issues - 2

  37. Unresolved Previous Issues - 3

  38. Unresolved Previous Issues - 4

  39. Unresolved Previous Issues - 5

  40. Unresolved Previous Issues - 6

  41. Unresolved Previous Issues - 7

  42. Unresolved Previous Issues - 8

  43. Type Tested Compliance • Manufacturers have begun to enter their generation units into the ENA’s type test database. • The ENA is seeking tenders from engineering consultants to review completeness etc and compliance of the entries.

  44. Equipment Certificates • The ENA has received some queries from organizations engaged in creating equipment certificates for G98 and G99 compliant generating units. • The ENA is supporting those organizations in the expectation that one or more of them will succeed in awarding equipment certificates to one or more manufacturers.

  45. Future G99 updates • Issues that seem to suggest a further minor formal modification to G99 is needed soon: • Type B Reactive Power requirements (ie Issue 42) • Reciprocating gas engine generation relocation (ie Issue 29) • Slow acting hydro LFSM-O (ie issue 34) • Minimum stable operation • CE marking (ie Issues 35 and 36) • Potentially allow for different droops for LFSM-O and LFSM-U for type C and D in the SAF (and DDRC).

  46. Outstanding Actions • Please see notes of March meeting

  47. AOB and Next meeting • AOB • Next meeting • 16 April 2019

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