Slide 1: Distributed Generation Technical Interconnection Requirements Addendum
Distributed Generation Technical Interconnection Requirements Addendum Distribution Voltage Performance Criteria and Requirements Follow up Webinar 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. Criteria Overview • Feeder level performance criteria • Station level performance criteria 3. Interrelationship between feeder and station level voltage performance criteria 4. Answers/Comments to Questions from First Webinar 5. Questions 2
Slide 3: Introduction
Introduction • The first webinar on the Technical Interconnection Requirement Addendum presented on September 9 reviewed: - New voltage requirements and criteria - Questions and comments on the proposed criteria • Today’s follow up webinar discusses: - Criteria and responses to frequently asked ques
Slide 4: Introduction (cont'd)
Introduction (cont’d) • 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 identified parameters and re
Slide 5: Experience with Long Feeders Voltage-Power Profile
Experience with Long Feeders Voltage-Power Profile 5
Slide 6: Criteria Overview
Criteria Overview The basis of other performance criteria • DGs shall not actively regulate their Point of Common Coupling (PCC) voltages • At a time when Hydro One distribution system infrastructure can not support DG active voltage control, this criterion enables Hydro One to – manage reactive pow
Slide 7: Criteria Overview: Feeder level performance criteria
Criteria Overview Feeder level performance criteria • PCC voltage shall be maintained within 0.94 ~1.06 p.u. and shall not be lower than pre-connection voltage • At the feeder level, DGs shall not contribute to short- term voltage fluctuation anywhere on the feeder by more than 1% 7
Slide 8: Criteria Overview: Feeder level criteria comments
Criteria Overview Feeder level performance criteria (cont’d) Comments • The feeder level performance criteria will - ensure feeder voltages are within CSA limits - avoid customer complaints due to excessive voltage fluctuations - prevent excessive operation of voltage regulating facilities • Feeder
Slide 9: Criteria Overview: Station level performance criteria
Criteria Overview Station level performance criteria • 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% • Tripping of all DGs connected to the station shall not cause abrupt voltage change t
Slide 10: Criteria Overview: Station level criteria comments
Criteria Overview Station level performance criteria (cont’d) Comments • The station level performance criteria will – avoid customer complaints due to excessive voltage fluctuations – prevent excessive operation of voltage regulating facilities – prevent unacceptable post-contingency voltages • Sta
Slide 11: Interrelationship between feeder and station level criteria
Interrelationship between feeder and station level criteria • Increasing the feeder DG capacity at the expense of violating the feeder level voltage criteria decreases the station DG capacity • At feeder level, increasing the DG size at a given location increases the reactive power consumption attri
Slide 12: Example: Feeder DG capacity vs station capacity
Example: Feeder DG capacity vs station capacity 12
Slide 13: Example: Feeder DG capacity vs station capacity (cont'd)
Example: Feeder DG capacity vs station capacity (cont’d) 13
Slide 14: Example: Feeder DG capacity vs station capacity (cont'd)
Example: Feeder DG capacity vs station capacity (cont’d) 14
Slide 15: Example: Feeder DG capacity vs station capacity (cont'd)
Example: Feeder DG capacity vs station capacity (cont’d) 15
Slide 16: Interrelationship between feeder and station level criteria (cont'd)
Interrelationship between feeder and station level criteria (cont’d) Conclusions from the example • DG2 is connected far from the station with lower X/R. It consumes more reactive power per MW to maintain feeder voltage • Lowering the size of DG2 allows more DG connection to the station • The exampl
Slide 17: Question 1: How far from the station is too far?
Question 1 How far from the station is considered too far? • The answer depends very much on the overall X/R ratio • In distribution system, electrical distance is represented by both resistance and reactance • Hydro One feeder (13.8kV -44kV) reactance is about 0.4 ohm/km, but feeder X/R ratio range
Slide 18: Question 1 (cont'd)
Question 1 (cont’d) How far from the station is considered too far? • The high resistive component of the impedance causes PCC voltage to rise due to DG power output. For a given physical distance, this voltage rise is higher if X/R ratio is lower, and hence the feeder appears to be “electrically lo
Slide 19: Question 2: Limiting voltage fluctuation without voltage control
Question 2 How can voltage fluctuation be limited without voltage control? • Both published technical literature and our own findings confirm that constant power factor control can limit voltage fluctuation • Hydro One will assign PCC power factor according to specific system conditions • Example: C
Slide 20: Question 2 (cont'd)
Question 2 (cont’d) How can voltage fluctuation be limited without voltage control? 1 .005 1 .004 1.004 p.u. 1 .003 V 1 .002 This V-P profile shows voltage 1 .001 fluctuation is constrained with a leading power factor of 0.97 1 0 .999 0 .998 1.000 p.u. 0 .997 0 .996 0 .995 0 1 2 3 4 5 6 7 8 9 10 P (
Slide 21: Question 3: Voltage control with limited reactive power
Question 3 Is voltage control with limited reactive power acceptable ? The question proposes to: • Exercise DG voltage control with “limited” reactive power in order to limit post-contingency voltage deviation. • This proposal has some disadvantages as outlined in the next slide 21
Slide 22: Question 3 (cont'd)
Question 3 (cont’d) Is voltage control with limited reactive power acceptable ? Disadvantages of the Proposal • Voltage control responds to both load and generation variations. The limited reactive power available for voltage control will likely be used to respond to load, leaving insufficient react
Slide 23: Question 4: What is short term voltage fluctuation?
Question 4 What is short term voltage fluctuation? • Here short term voltage fluctuation refers to the voltage fluctuation caused by DG power variation as opposed to that caused by slow load variation. The time-frame is within minutes • Hydro One uses voltage-power profiles to evaluate the short ter
Slide 24: Question 4 (cont'd)
Question 4 (cont’d) What is short term voltage fluctuation? 1 .005 1 .004 V (p.u.) 1 .003 V-P profile 1 .002 1 .001 V fluctuation 1 0 .999 Power variation 0 .998 0 .997 0 .996 P (MW) 0 .995 0 1 2 3 4 5 6 7 8 9 10 24
Slide 25: Question 5: Power factor range at the PCC
Question 5 Will a power factor range at the PCC be acceptable ? • Hydro One requires constant power factor operation at the PCC for all DG output conditions to limit voltage fluctuation and maintain acceptable voltage profile • Hydro One determines the power factor settings according to system condi
Slide 26: 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 26
Slide 27: Questions?
Questions? Please submit your questions on today’s webinar topic “Distribution Voltage Performance Criteria and Requirements” For questions unrelated to today’s webinar, please contact your local Hydro One Account Executive or email your question to DGConnectionReq@HydroOne.com 27
Slide 28: Example: Feeder DG capacity vs station capacity
Example: Feeder DG capacity vs station capacity X/R =4 DG1 X/R =1.9 DG2 X/R =2.5 DG3 Scenario 1 – Pre-contingency, DG2 20 MW DG2 severely violating Criteria 2, 3 28
Slide 29: Example: Feeder DG capacity vs station capacity
Example: Feeder DG capacity vs station capacity DG1 DG2 DG3 LV bus voltage >1.1 p.u. after DGs trip (total 30 MW) 29
Slide 30: Example: Feeder DG capacity vs station capacity (cont'd)
Example: Feeder DG capacity vs station capacity (cont’d) DG1 DG2 DG3 Scenario 2 – Pre-contingency, DG2 10 MW DG2 reduced to 10 MW 30
Slide 31: Example: Feeder DG capacity vs station capacity (cont'd)
Example: Feeder DG capacity vs station capacity (cont’d) DG1 DG2 DG3 LV bus voltage 1.094 p.u. after DGs trip (total 40 MW) 31