Slide 1: Distributed Generation Technical Interconnection Requirements Addendum
Distributed Generation Technical Interconnection Requirements Addendum Distribution Voltage Performance Criteria and Requirements September 2010 Audio Dial-in: TEL: 416-641-6150 / 1-800-952-5114 Participant Pass Code: 1874313 1
Slide 2: Presentation Overview
Presentation Overview 1. Introduction 2. Experience with Long Feeders 3. Purpose of Addendum 4. An Important Existing Technical Interconnection Requirement (TIR) on Voltage 5. Proposed Modification 6. Feedback Process 7. Questions 2
Slide 3: Introduction
Introduction • Based on experience with the connection of Distributed Generators (DGs) on long feeders, Hydro One became aware of numerous voltage performance issues • Substantiated by field measurements • Traditional limits (400A rule) proved insufficient • New requirements identified and proposed
Slide 4: Experience with Long Feeders
Experience with Long Feeders • A system with long, rural feeders, such as Hydro One’s distribution system, is much more susceptible to voltage swings that result from variable power injection from generators • As the distance of the connection point from the station increases, voltage becomes more s
Slide 5: Experience with Long Feeders (cont'd)
Experience with Long Feeders (cont’d) • Experience has shown that changes in voltage (both voltage rise and voltage fall) can occur and impact customers • This is further aggravated when the connected generation is large, the output is variable and the electrical system strength is weak 5
Slide 6: Experience with Long Feeders: Voltage-Power Profile
Experience with Long Feeders Voltage-Power Profile 6
Slide 7: Purpose of Addendum
Purpose of Addendum • Add to and supplement §2.2.2.1 of the existing TIR including additional requirements for: – Acceptable voltage levels at the Point of Common Coupling (PCC) – Acceptable voltage variation anywhere on the feeder or at the supply station low-voltage bus – Acceptable voltages on th
Slide 8: Existing TIR Requirement Criterion 1
Existing TIR Requirement Criterion 1 • DGs shall not actively regulate their Point of Common Coupling (PCC) voltages. (Clause 2.2.2.1, iii, Page 66 of existing TIR) • DG active voltage regulation means the DG will continuously monitor the feeder voltage and respond to it by automatically adjusting i
Slide 9: Existing TIR Requirement Criterion 1 (cont'd)
Existing TIR Requirement Criterion 1 (cont’d) Technical Basis • DG active voltage control interferes with existing voltage regulating facilities, causing unacceptable post-contingency voltage if DGs trip. (Scenario 1) • DG active voltage control of one location may aggravate voltage fluctuation at o
Slide 10: Existing TIR Requirement Criterion 1 (cont'd): DG voltage control interferes with VR
Existing TIR Requirement Criterion 1 (cont’d) Scenario 1 - DG voltage control interferes with VR Station Voltage Bus Regulator Load downstream DG Load voltage controlled by the DG. The voltage regulator does not respond to load correctly. Load voltage uncontrolled immediately after the DG trips. 10
Slide 11: Existing TIR Requirement Criterion 1 (cont'd): DG voltage control aggravates fluctuation
Existing TIR Requirement Criterion 1 (cont’d) Scenario 2 – DG voltage control aggravates fluctuation Station LV bus PCC P2 HV line Q2 Q1 P1 High X/R Low X/R DG DG aggressively varies Q1 to control PCC voltage as P1 fluctuating. As result, Q2 fluctuation at station LV bus is aggravated. Station LV bu
Slide 12: Proposed Modification Criterion 2
Proposed Modification Criterion 2 • PCC voltage shall be maintained within 0.94 ~1.06 p.u. and shall not be lower than pre-connection voltage • Existing TIR does not define a PCC voltage constraint with respect to pre-connection voltage. • The proposed modification is to ensure the feeder voltages a
Slide 13: Proposed Modification Criterion 2 (cont'd)
Proposed Modification Criterion 2 (cont’d) Technical basis • Hydro One primary feeders supply step-down transformers that may not have under-load tap changers. • Even if primary feeder voltages are well above 0.94 p.u., voltages of feeder circuits supplied by those step-down transformers may well be
Slide 14: Proposed Modification Criterion 3
Proposed Modification Criterion 3 • At the feeder level, the DG shall not contribute to short- term voltage fluctuation anywhere on the feeder by more than 1% • This addresses customer complaints due to short-term voltage fluctuation and prevents frequent operations of voltage regulating tap changer
Slide 15: Proposed Modification Criterion 3 (cont'd)
Proposed Modification Criterion 3 (cont’d) Technical basis • Short term voltage fluctuation due to load variation is well below 1%. Hydro One has received complaints of short-term voltage fluctuation due to DGs. • The dead-band of existing Hydro One voltage regulating facilities is about 2%. We choo
Slide 16: Proposed Modification Criterion 3 (cont'd)
Proposed Modification Criterion 3 (cont’d) Technical basis • DGs that violate the criterion typically absorb more reactive power per MW as compared to the DGs that comply with the criterion. • However, reactive power consumption attributed to DGs is limited by the post-contingency voltage performanc
Slide 17: Proposed Modification Criterion 4
Proposed Modification Criterion 4 • At the station level, all DGs connected to the TS/DS shall not collectively contribute to short term voltage fluctuation at the station LV bus by more than 1% • The rationale for the criterion is similar to those for Criterion 3 – to address customer complaints du
Slide 18: Proposed Modification Criterion 5
Proposed Modification Criterion 5 • Tripping of all DGs connected to the station shall not cause abrupt voltage change to result in a voltage above 110% of nominal bus voltage, or less than 90% of nominal bus voltage, after a single contingency and before the station Under Load Tap Changer (ULTC)/fe
Slide 19: Proposed Modification Criterion 5 (cont'd)
Proposed Modification Criterion 5 (cont’d) Technical basis • Post-contingency voltage limit is consistent with the existing TIR • The voltage limit takes into account IEC standard, the IESO SIA criteria and is also consistent with the Information Technology Industry Council (ITIC) curve for supply t
Slide 20: Proposed Modification Criterion 5 (cont'd)
Proposed Modification Criterion 5 (cont’d) Technical Implication • Net change in reactive power consumption from the system due to DG tripping should be minimized to prevent excessive voltage change before regulating facilities can react 20
Slide 21: Follow up Webinar
Follow up Webinar • Hydro One will hold a second webinar on this topic • Topics for next webinar will include: – Brief review of long feeder issues – Review of Hydro One TIR addendum on voltage criteria 21
Slide 22: Questions?
Questions? We will answer questions only on today’s Webinar - Distribution Voltage Performance Criteria and Requirements For questions outside of the scope of the Webinar, please contact your local Hydro One Account Executive or email your question to DGConnectionReq@HydroOne.com 22
Slide 23: Feedback Process
Feedback Process • Additional questions and/or feedback regarding the addendum will be accepted for a period of one week • Please use the following e-mail address to communicate your comments DGConnectionReq@HydroOne.com 23