Load forecast

Toronto Hydro‐Electric System Limited
EB‐2012‐0064
Tab 4
Schedule B17
Appendix 2
ORIGINAL
(14 pages)

Appendix 2: Load Growth

In Downtown Toronto Area

Figure 1 Downtown Core (photo courtesy Myles Burke Architectural Models)

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Contents
In Downtown Toronto Area ...................................................................................................................... 1
1. Introduction: ............................................................................................................................................ 3
1.1 Purpose ............................................................................................................................................. 3
1.2 Background ....................................................................................................................................... 3
2. Load Growth methodology ................................................................................................................... 4
2.1 Forecasting Process ....................................................................................................................... 4
2.2 Model ................................................................................................................................................. 5
2.2.1 Weather Sensitivity .................................................................................................................. 5
2.2.2 Peak Demand Growth Rate .................................................................................................... 7
2.2.3 Assumptions .............................................................................................................................. 8
2.3 Anticipated Growth ........................................................................................................................ 10
2.3.1City of Toronto Vision ............................................................................................................. 10
2.3.2 New Building Permit Applications and Zoning Applications ............................................ 12
2.3.3 New Customer Connection ................................................................................................... 13
3. Summary ............................................................................................................................................... 14

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1. Introduction:
1.1 Purpose1
This appendix further discusses load growth of Toronto downtown transformer stations based
upon stated assumptions and THESL methodology. The primary purpose of this appendix is to
demonstrate the load growth in proximity of the Bremner Transformer Station by examining
forecasts, historical data and proposed customer connections in the Toronto downtown area
circumscribed by the service areas of the five downtown transformer stations.
Two important components of the THESL load forecast are the natural load growth and the new
customer connection requests. In this document, THESL validates the assumptions associated
with calculation of natural load growth in the downtown Toronto core (2% growth per year).
THESL also examines the magnitude of actual customer connection requests and future
developments in the City of Toronto.
Table 1 Load Forecasts (MVA) by Station
Station
Station
Rating
Year
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026
Cecil 224 182 189 196 199 203 207 212 216 220 224 229 233 239 242 248 252
Esplanade 198 175 173 177 182 187 192 196 199 204 208 212 216 221 225 230 234
Strachan 175 122 127 130 131 133 140 143 147 151 153 157 159 163 166 169 172
Terauley* 240 199 205 211 215 220 225 229 234 238 243 248 252 258 263 269 273
Windsor 340 304 306 315 324 328 335 342 349 355 362 371 377 383 391 399 405
Total 1177 982 1000 1029 1051 1071 1099 1122 1145 1168 1190 1217 1237 1264 1287 1315 1336
1.2 Background
THESL distributes electricity to its customers in downtown corridor via 13.8kV feeders from the
115kV/13.8kV substations. This appendix does not focus on transmission planning issues
directly nor does it reflect transmission capacity limitations. However, it is worth noting that the

1
This document is not replacement for official THESL stations load forecast which includes all THSEL’s Stations

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new Bremner TS has for many years been included in HONI plan to meet the future load growth
of the Toronto downtown area. For example, Figure 2 below indicates a ‘break out’ at HONI’s
existing Front Street tunnel, installed in 2007 with the intention of connecting said tunnel to
Bremner TS.
Figure 2 Existing break out at HONI transmission tunnel for Bremner TS tunnel
The resolution of the transmission capacity issue of downtown Toronto is considered in ongoing
cooperative planning between THESL and HONI.
2. Load Growth methodology
2.1 Forecasting Process
As the purpose of the forecast is to assess station bus capacity adequacy, the summer and
winter maximum peak demands are forecast, rather than monthly peak demands.
The process for calculating peak demands follows three steps:
a) Historical summer/winter peak demand for a bus is weather corrected,
b) New loads are added to the weather- corrected demands according to the build-up
formula, and
c) Growth rates are applied to obtain annual peak demand forecasts for the Study
period. The natural growth rate for the first two years of the study period is assumed to
be zero. The forecast increase in demand is exclusively driven by new customer
connections.

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When projected load for a station bus exceeds the bus capacity during the first five years of the
study period, remedial action is proposed and then the forecast is repeated to include the
remedial action.
The following alternatives are considered, in order of preference, to remedy the bus/station
capacity shortfall:
1. Load transfer to another bus or station;
2. Upgrade of station bus capacity;
3. Upgrade of station transformer capacity;
4. Station expansion, i.e. new bus;
5. New station.
Figure 3 Forecasting Methodology Schematics

2.2 Model
2.2.1 Weather Sensitivity
THESL normalizes downtown station bus peak demands to a mean daily temperature of 27°C
for the summer forecast. The summer forecast is the most restrictive. This temperature is the

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average of the recorded mean daily temperature of the days that the buses reached highest
peak demand over the period of 1998 to 2008.
A linear regression model is used to calculate bus weather sensitivity (b) and the intercept
parameter (a) from historical daily peak load (Y) and daily mean temperature (X) observations.
The mathematical equation is:
Y= bx + a
Where,
Y = the daily peak load (MVA)
b = the slope of the trend line (MVA/°C),
X = the daily mean temperature (°C), and
a = the y-axis intercept (MVA).
The daily station bus peak demand data is obtained from station revenue metering. Daily mean
temperature data is obtained from Environment Canada’s Monthly Meteorological Summary
Report. Since extreme temperature-load behaviour is of interest, only data for the summer and
winter months are used for the regression model. Data for the months of June, July and August
are used for the calculation of bus summer-season sensitivity. Data for the months of
December, January and February are used for bus winter-season sensitivity. Weekends and
holidays are excluded from model data as they differ dramatically from the weekday loads
If ‘N’ is the number of Y-X readings, then the value of ‘b’, bus weather sensitivity(MVA/ C°) can
be found by using the Method of Least Squares, as follows:
Using spreadsheet programs, bus weather sensitivity calculations and normalization of starting
bus peak demands are performed.

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2.2.2 Peak Demand Growth Rate
To determine demand growth rate, five year actual peak load data for the five downtown
transformer stations was studied. Load growth rates are determined using a Time-Trend model.
The relationship between x and y in the Time-Trend model is exponential, taking the form y =
ab
x
. After taking natural logarithms of the equation it becomes:
ln y = ln a + x lnb
Where ‘ln a’ and ‘ln b’ represent the constants in the equation. ‘ln y’ and ‘x’ now have a linear
relationship and the Least Squares method can be applied. The equation can be simplified as:
Y = A + Bx
Where,
A = ‘ln a’ as described before,
B = ‘ln b’ which is the slope of the trend line,
x = time (i.e.; 2007, 2008, 2009, … )
Y = the natural logarithm of bus summer/winter peak load (MVA).
The annual peak load data is obtained from station revenue metering. As with the weather
sensitivity model in section 2.2.1, the extreme temperature-load behaviour of the Time-Trend
model is of interest. Data for the months June, July and August were used for calculation of the
summer peak load, and data for the months of December, January and February are used for
bus winter peak load. If ‘N’ is the number of data, then the value of ‘B’, which is the slope of the
line, can be found by using the Method of Least Squares. The following equation is used to
compute the slope ‘B’.

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Table 2: 5 Year Historical load data
2007 2008 2009 2010 20112
Cecil 169 164 176 181 187
Strachan 118 104 119 117 138
Windsor 284 277 295 303 311
Terauley 194 194 188 185 190
Esplanade 168 164 169 176 180
Sum (MVA) 933 903 947 962 1006
: ln (load) 6.84 6.81 6.85 6.87 6.91
The value for B was established using the actual five year peak load.
∑ ∑ ∑
∑ ∑
0.0214
The original exponential model y=ab
x
can be re-written as y=a(1+g)x
, where g is the annual
growth rate. Thus, the bus percentage growth rate ‘g’ is calculated using equation:
g = (e B
− 1) × 100 %
The growth rate for the past five years based upon a B of 0.0214 was determined.
g= 2.16%
2.2.3 Assumptions
2.2.3.1 New Customer Connections Load Build-up
New customer load is included in the forecast only for known projects for which THESL has
been approached for service connections.

2
Actual data as of April 2012.

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The following load build-up guidelines are used in absence of customer load build-up:
Table 3 Load Build Up
Based upon past experience, not all projects materialize and those that do materialize usually
overestimate their peak demand. Therefore prospective new customer peak demand estimates
are reduced by 50% to achieve a more realistic peak demand estimate. Section 2.3.3 shows a
subset of new customer requests received by THESL.
2.2.3.2 Load Growth Rate for New Loads
For new customer loads, a zero percent growth rate is used for the first two years of the forecast
period.
2.2.3.3 Conservation and Demand Management (CDM)
The Ontario Power Authority and THESL have both developed and implemented
complementary projects over the past few years. The major program portfolios are:
1. Conservation
2. Demand Response
3. Distributed Energy
In the shorter term, where committed projects are known, the potential impact of the project is
taken into account in the forecasts. Committed generation projects are easier to quantify, as
their location and size are clear and potential contributions could be estimated from signed
agreements. At this time, THESL takes into consideration new committed generation projects
that are over 10MW in size when performing the forecast. Once the unit is in service, in the
absence of physical assurance of operation, the actual impact on the bus load is reflected in the
actual historical bus load data and therefore it is accounted for in the forecast. Where CDM

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projects are installed and commissioned, the actual impact on bus load is reflected in the actual
historical bus load data, and therefore accounted for in the forecasts.
2.3 Anticipated Growth
For the first three years of forecast period new loads are added only when THESL has direct
knowledge of new customer connections by means of requests. This mechanism enables
THESL to forecast the immediate need of distribution system while forecasting long term growth
using a calculated load growth rate.
Downtown Toronto is a focal point of development, growth and urbanization. Toronto has
recently experienced a surge of both residential and non-residential growth with construction
cranes maintaining a constant presence on the City’s skyline. As result, increases in electrical
demand will be experienced by THESL in the near future.
2.3.1 City of Toronto Vision
Toronto’s Official Plan, which came into force in June 2006, is a road map for how the city will
develop over the next 20 years. Most of the new developments will take place in target areas
such as the downtown Toronto area. As result of the Official Plan, Toronto’s development
industry is strong and continually invests in new projects in the City. In the 4½ years after
Official Plan came into force, 1,696 development projects, with 106,848 residential units and
over 4.23 million m2
of non-residential gross floor area (“GFA”) proposed, have been submitted
to the City Planning Division for approval.

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Figure 4: Downtown and Central Waterfront development Activity
Figure 5: Proposed Development in City of Toronto
The Downtown and Central Waterfront area are two of the driving forces of development in the
City of Toronto. Over 34,500 units and 977,000 m2
of non-residential GFA were proposed in the
area between June 2006 and December 2010. This is almost one- third of the residential units

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and one- quarter of the non-residential GFA proposed in the entire city. Figure 4 shows the
distribution of residential units and non-residential GFA throughout the Downtown. Despite
these large magnitudes of development, anticipated load for these projects is not included in the
forecast due to unknown construction and occupancy timeline as well as absence of customer
connection for proposed projects.
2.3.2 New Building Permit Applications and Zoning Applications
A large number of building permit applications and zoning applications for significant
developments have been submitted to the City of Toronto. Since these projects are in early
stages of development, new customer connection requests have not yet been submitted to
THESL and therefore, additional demands for such projects are not included in the forecast. A
number of large proposed developments in the proximity of Windsor TS and Bremner TS are
summarized in Table 4. Although there is not any accurate information on load requirements of
proposed projects, conservative estimates were made based on gross floor area (GFA) to
quantify impact of the developments on the THESL distribution system.
Table 4: Selected New Building Permit and zoning applications
Address
Add.
Load

Address
Add.
load
(kVA) (kVA)
<confidential customer information> 3,326 <confidential customer information> 976
<confidential customer information> 2,486 <confidential customer information> TBD
<confidential customer information> 988 <confidential customer information> TBD
If GFA is unavailable, additional load is denoted by ‘TBD’

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2.3.3 New Customer Connections
Toronto Hydro has received customer connection requests for 65.9 MVA of additional loads for
both existing building and new buildings in the proximity of the future Bremner station and
existing Windsor station. The geographical location of the requests is shown in Table 5. As
mentioned earlier, customer connection requests have been accounted for in the load forecast
using applicable assumptions.
Table 5: Customer Connection Requests in Proximity of Future Bremner TS
Request Date Customer Name Customer Address
Additional
Load (KVA)
May 17, 2010 <confidential> <confidential> 14500
August 2, 2012 <confidential> <confidential> 10000
June 12, 2011 <confidential> <confidential> 8000
July 11, 2011 <confidential> <confidential> 5241
November 1, 2012 <confidential> <confidential> 4600
September 26, 2011 <confidential> <confidential> 3792
October 16, 2008 <confidential> <confidential> 3500
April 4, 2011 <confidential> <confidential> 2800
May 16, 2011 <confidential> <confidential> 1801
January 30, 2012 <confidential> <confidential> 1487
February 26, 2010 <confidential> <confidential> 1200
March 16, 2012 <confidential> <confidential> 1049
Various Incremental requests Various (not mapped) 2470
Energization dates may vary depending on infrastructure (Service dates 2011 to 2014)
Figure 6 Downtown Toronto Load Growth

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3. Summary
The natural load growth in the downtown core has been set at 2% since 2009 for the purposes
of the load forecast. In previous sections, THESL has shown that load growth over the last 5
years is 2.16%, validating the load growth assumptions.
It should be noted that over the last 4 years, THESL has experienced an elevated growth rate of
approximately 3.5% in the downtown core as a result of the local construction boom. This
growth is consistent with the City of Toronto Official Plan and THESL customer connection
requests.
Therefore, the 2% natural growth assumptions used in THESL midterm load forecasts to 2030
can be characterized as conservative.

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