Slide 1: Update on Capacity Constraints with Distribution System
Update on Capacity Constraints with Distribution System Mark Fukuzawa Daffyd Roderick Ayesha Sabouba March 24, 2010
Slide 2: Committed to Connecting Renewables
Committed to Connecting Renewables • We know generators rely on us to manage our obligations in a manner that brings certainty to the timing of their projects. • We understand that what we do and when we do it can have financial implications for generators. We will continue to work with generators t
Slide 3: Renewable Connections: Status 2010
Renewable Connections: Status 2010 • Hydro One has connected 112 generators to its distribution system totaling 377 MW and has more than 500 MW of RESOP contracted generation which the Company expects to connect in 2010. • The Company has connected more than 5,500 MW of new generation to the transmi
Slide 4: Agenda for Today
Agenda for Today 1. Overview of Capacity Challenges facing Hydro One and plans to manage issues – Feeder Distance Limitation – Short Circuit – Dual Windings Transformers 2. Q and A Session 4
Slide 5: Challenges with Capacity
Challenges with Capacity • Capacity is fluid, not static – System load is continually changing, new generation outside of FIT • Newly connected renewable generator sites are uncovering unforeseen impacts to the grid system – Long Feeder, Short Circuit Considerations, Transformer Limitations • Object
Slide 6: Hydro One Experience - Long Feeders
Hydro One Experience - Long Feeders 6
Slide 7: Presentation Overview
Presentation Overview • Background • Identify the developments • Implications of a new consideration for long feeders • Impact on Distribution Availability Test 7
Slide 8: Background
Background • Connecting generators to distribution is a new experience: – Generation connected to long feeders – Short circuit considerations – Transformer station capacity • Comparison with other jurisdictions – This is a learning experience for all 8
Slide 9: Hydro One Distribution Experience With Long Feeders
Hydro One Distribution Experience With Long Feeders • As the distance of the connection point from the station increases, voltage becomes more sensitive to changes in injected power • Large generators far from the station can have a significant impact on voltage levels in the vicinity of the connect
Slide 10: Voltage vs Power Profile for Generation Connections on Long Feeders
Voltage vs Power Profile for Generation Connections on Long Feeders Low Impact Zone High Impact Zone V (pu) P (MW) increasing P 10
Slide 11: Considerations for Long Feeders
Considerations for Long Feeders • Additional technical analysis in Distribution Availability Test and Connection Impact Assessment will consider the voltage impact of intermittent power sources on existing customers – Greater assurance that projects will be compatible with existing customers • It is
Slide 12: Considerations for Long Feeders
Considerations for Long Feeders • More generation can be accommodated the closer they are to the transformer station • Published capacity assumes generators are ideally situated Very close Close ~ Midway Far 12
Slide 13: Considerations for Long Feeders
Considerations for Long Feeders • A generator connected far away from the transformer station can affect the capability of the overall feeder Very close Close Midway Far ~ 13
Slide 14: Management Plan – Long Feeder Issue
Management Plan – Long Feeder Issue Communication to Impacted FIT Projects • Met with known proponents who will be impacted by distance issue • If required, alteration options will be explored in detail during CIA phase Proceed to Connection FIT Projects CIA Apps completed Generator In OPA outlining
Slide 15: Management Plan – Long Feeder Issue
Management Plan – Long Feeder Issue Grid Integration of Existing RESOP Projects • There are existing RESOP projects currently being implemented on long feeders • Alterations to projects being considered on a case-by-case basis • Do not foresee any impact to planned In-Service Dates. Alterations in s
Slide 16: Management Plan – Long Feeder Issue
Management Plan – Long Feeder Issue Development of a Longer Term Solution • Working group being formalized to collect input from generators and manufacturers to consider possible options in dealing with the issue • Outstanding considerations include • Impacts from different types of generation • Vol
Slide 17: Station Capacity
Station Capacity © 2009 Hydro One Networks, Inc. All rights reserved
Slide 18: Summary
Summary • Station capacity on Hydro One’s List of Allocated Capacity was adjusted in preparation for FIT • The Connection Availability Table posted by the OPA at FIT launch includes station capacity values • OPA’s values account for RESOP contracts awarded at the time of FIT launch • Station capacit
Slide 19: Summary
Summary • Hydro One’s List of Allocated Capacity shows allocated capacity for projects including those that do not have RESOP contracts • The following slides provide further background for the recent changes to station capacity values 19
Slide 20: Background
Background • Hydro One substations have been designed, rated and operated as step-down substation with power flowing from higher system voltage to lower system voltage • Large accumulation of distribution connected generation on these stations could result in reversal of normal power flows • Distrib
Slide 21: Station Capacity Limits Definition
Station Capacity Limits Definition • Reflecting our obligations as both a transmitter and a distributor, the following technical capacity limit has been determined by Hydro One: − Reverse power flow is not to exceed 60% of station capacity to protect the system in a situation where 1 transformer is
Slide 22: HONI Experience with Station Capacity
HONI Experience with Station Capacity In preparation for FIT, Hydro One reviewed station capacity considering actual experience and new information. Highlights: • Some dual secondary winding transformers do not allow for reverse power flow conditions • There was a reduction in minimum system load •
Slide 23: Station Thermal Capacity Limit
Station Thermal Capacity Limit Two types of transformers: • Single secondary winding one HV winding, one LV winding • Dual secondary winding one HV winding, two LV winding 23
Slide 24: Dual Secondary Winding Transformers
Dual Secondary Winding Transformers • Equal reverse flow in the two secondary windings cannot be assumed • Based on information from transformer manufacturers, Hydro One has determined that some dual secondary winding transformers cannot withstand forward flow in one secondary winding while there is
Slide 25: Thermal Capacity Conclusions
Thermal Capacity Conclusions • The station capacity shown on Hydro One’s List of Allocated Capacity and OPA’s Connection Availability Table reflects: − Dual secondary winding transformer capacity − Reduction in system load − More detailed analysis 25
Slide 26: Management Plan to Address Transformer Issue
Management Plan to Address Transformer Issue • Reductions in capacity due to transformer issues were adjusted to accommodate expected projects in FIT launch • Currently reviewing priortization plans to replace end- of-life transformers. Most problematic transformers are scheduled for replacement. •
Slide 27: Short Circuit
Short Circuit • Short circuit limitations were previously identified after a Connection Impact Assessment (CIA) was completed • Some short circuit limitations are presently identified on Hydro One’s List of Allocated Capacity and on OPA’s Connection Availability Table • Short circuit information is
Slide 28: Short Circuit
Short Circuit TSC or equipment limit Remaining capacity to connect distributed generators to the station Short circuit contribution from existing generators and large motor loads connected to the station Short circuit contribution to the station from the existing transmission system 0 28
Slide 29: Short Circuit
Short Circuit • The short circuit contribution of a generator at a station depends on the following parameters: • Generator technology (inverter, rotating machine) • Distance from the station (greater distance results in lower short circuit contribution) 29
Slide 30: Short Circuit Conclusions
Short Circuit Conclusions • Station capacities shown on Hydro One’s List of Allocated Capacity and on OPA’s Connection Availability Table presently reflect known short circuit limits • Short Circuit issues will not be considered in TAT and DAT tests • Short circuit levels will be studied in the Conn
Slide 31: Transforming Ontario's Power Grid
Transforming Ontario’s Power Grid While there are short-term challenges, Hydro One is dedicated to enabling the transformation of Ontario’s power system and connecting renewable generators. 31
Slide 32: Thank You
Thank You Please stay in touch with your account executive and monitor www.HydroOne.com for future developments 32