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1. Introduction 2. Maximum HVDC Loading3. Transmission Options4. Planning Studies for FCLs5. Conclusions
225MW
2175 MW225 MW
LimesoneLong Spruce
Kettle
Jenpeg
Pine FallsGreat FallsMcArthur FallsSeven SistersPointe du BoisSlave FallsSelkirk
Brandon
Grand Rapids
Laurie River
Kelsey
Selkirk -Natural Gas
Brandon – Coal
Brandon – Combustion Turbine
Diesel – Brochet, Lac Brochet, Tadoule Lake, Shamattawa
Route of HVDC
Other transmission
Wuskwatim Services for over 500 000 electricity and 250 000 gas customers
A total generating capacity about 5700 MW produced mainly by 15 hydroelectric stations (95%), and 2 thermal stations.
Manitoba Hydro Generating Stations and Interconnections
1. INTRODUCTION
Provide about 70% generating capacity.
Bipole I and II HVdc lines constructed on the same Right-of-way in 1970
900km overhead lines, difficult terrain and access in the north
Terminated at a common station – Dorsey (inverter)
Parallel operation during emergency (i.e. the loss of one dc tower ) to use the full dc line capacity
The Existing Bipole I and II System
BPI converter : +/- 463.5kV/1854MW
Commissioned in 1971
Three valve groups per pole
Initially built with Mercury Valves
Refurbished with thyrisors in 1992 and 2004
The Existing Bipole I and II System
BP2 converter: +/- 500kV/2000MW
Two valve groups per pole
Thyristor valves are in service in the range of 30 to 37 years.
Typical thyristor life time around 30-35 year as per industry practice
Future Northern Collector System (NCS) includes five generating stations and three HVDC rectifier stations, of which two new generating stations and Bipole III are new additions to the system.
Dorsey and Riel 230 kV station includes HVDC inverter station and major transmission lines connected to domestic loads and export services
Bipole I/II with over 900 km of DC line at the same corridor
Major Power System Expansion
Bipole III with 1380 km of DC line in west corridor
System Issues Mitigated
Bipole III transmission corridor added to the existing single corridorBipole III Riel station added to Dorsey
single location for Bipole I and II inverter stationsNew generation support to export sales
and domestic load demands
MAXIMUM HVDC LOADING RESULTING IN
A large increase in station fault level More coupled network in NCS and southern AC system• A large increase in DC power losses during a single fault at NCS• The operation of Under Frequency Load Shed (UFLS) protection
EVALUATING TRANSMISSION OPTIONS
Fault level study Power flow analysis Stability performance Cost estimate
2. MAXIMUM HVDC LOADING
Future Northern Collector System
Bipole III
ISD in 2018
(net 1350MW)(net 1224MW)
ISD in 2020ISD TBD
(net 980 MW)
KEEWATINOHK
1
21,2 %1
%VindropVoltage
VMIIF ∆=
Multi-infeed Interaction Factor (MIIF)The MIIF is a parameter for estimating the degree of voltage interaction between two ac busses to which converters are connected. The multi-infeed interaction factor MIIF could be obtained by applying 1% voltage change at the converter station being studied.
(1)
NCS system Converter Stations NO MIIF (%)
Existing System Radisson 1 MIIF21 = 0.315
Henday 2 MIIF12 = 0.417
Future SystemBipole III
+Keeyask+Conawapa
Radisson 1 MIIF31 = 0.195MIIF21 = 0.248
Henday 2 MIIF32 = 0.645MIIF21 = 0.342
Keewatinohk 3 MIIF13 = 0.228MIIF23 = 0.548
Table 1: MIIFs of NCS Converter Stations
Henday and Keewatinoow have high electrical coupling with MIIFs above 0.5, which could result in planning concerns.
TABLE 2: NCS VOLTAGE DURING A STATION FAULT
Fault LocationVoltage (p.u.)
Radisson Henday Keewatinoow
No Fault 1.00 1.00 1.00
Radisson 0 0.74 0.8
Henday 0.63 0 0.35
Long Spruce 0.43 0.43 0.45
Keewatinohk 0.79 0.5 0
Long Spruce and Keewatinohk station fault result in Hendaybus voltage falling below 0.5 pu.
Table 3: NCS POWER DURING A STATION FAULT
Fault LocationPower (MW)(% to its pre-fault level)
BP I BP II BP III
No Fault 1751 1887 1887
Radisson 0 1338 (71%) 1471(78%)
Henday 1034(59%) 0 448 (24%)
Long Spruce 640 (37%) 0 775 (41%)
Keewatinohk 1342 (77%) 0 0
Long Spruce and Keewatinohk station fault result in Hendaybus voltage falling below 0.5 pu and thus trig the Bipole II under voltage protection.
Line Fault Dorsey Riel
KY-R Line Near Radisson 59.4 59.5
LS-HEN Line Near Long Spruce
59.3 59.3
KW-HEN Line Near Henday
59.2 59.2
KW-HEN Line Near Keewatinohk
59.3 59.2
Based on North American Electric Reliability Corporation (NERC) criteria, any single AC fault with normal clearing should not cause the southern system to shed load. The MH load shedding protection is proposed to be set at 59.3 Hz with a duration of less than 65 ms in future system.
Table 4: Dorsey and Riel Frequency Responses
System Stations SLGF(kA) MSIR(kA) Cap (%)
Existing
LS 33.2 40 83
Radisson 41.1 50 82
Henday 31.6 50 63
BPIIIKY+CW
LS 40.6 40 102
Radisson 50.7 63 81
Henday 42 50 84
Table 5: Fault Level at NCS Stations
In the Northern Collector System, a Single Line to Ground Fault (SLGF) creates the highest station fault level. The practice at Manitoba Hydro is to maintain the station short circuit levels below 95% of their breaker’s Maximum Symmetrical Interrupting Ratings (MSIR). The Radisson station breakers will be replaced by 2020.
3. TRANSMISSION OPTIONSFollow system criteria and keep maximum generation production
Bipole III
ISD at 2018
(net 1350MW)(net 1024MW)
ISD at 2020ISD at 2020
500 KV
Kettle 2 units(204 MW)
500 kV ac corridor separated from Bipole I, II and III. Keeyask generation and Keetle 2 units connected to 500 kV ac transmission line. Higher costs Best Technical Option
500 kV
Option 1: 500 kV ac development
(net 980 MW)
KEEWATINOHK
Option 2: Splitting NCS – 100 MW Kettle to AC 230 KV system
KETTLE100 MW
TO AC
Connect one Kettle unit to AC Two Kettle units on NCS1 with 204 MW spare One Kettle unit on NCS2 with 473 MW spare Less costsMeet technical requirement
NCS1 NCS2(net 980 MW)
KEEWATINOHK
Option 3: Application of FCLs
Keep NCS intact without splittingFCLs installed near Henday to decouple BPII and BPIII during a faultLowest costsMeet technical requirements of reducing fault level and DC lossesNew technology and new application for transmission level
2xFCL3xFCL
(net 980 MW)
KEEWATINOHK
Table 6: Comparisons of Options
Options Description Generation in DC (MW)
DC Spare over Generation to largest
valve (MW)
Cost ($ M)
1 500 kV AC line 4719 1135MW /500MW Highest
2 Split NCS – 100 MW Kettle to AC2 units on NCS1 and
1 unit on NCS2
NCS1: 1650NCS2: 3827
NCS1: 204 MW/309 MWNCS2: 473 MW/575 MW
Meddle
3 FCLs 5579 575MW/575 Lowest
4. PLANNING STUDIES FOR OPTION 3 (FCL)
Short Circuit Current Calculation
Fault Locations
Breaker Rating (kA)
kA (no FCLs) kA (with FCLs)
BreakerCapability(%)
Radisson 63.0 50.70 49.50 78.6
Long Spruce 40.0 40.00 34.50 86.3
Henday 50.0 42.01 28.9 57.8
Keewatinohk 50.0 42.7 35.4 70.8
1) Radisson station breakers will be replaced before 2020 and their ratings are 63.0 kA as shown in the table.
2) Option 1 and 2 also meet this technical requirement
Load Flow Studies - NCS Bus Voltage
V <0.5 pu
Table 5: Bipole Power during the Station Faults
Southern Frequency Responses
Option 1 and 2 also meet this technical requirement.
5. CONCLUSIONS
a) Transmission options are recommended and examined on the optimal plans of transmission and generation.
b) The system criteria and cost estimate are considered.c) Planning studies including short circuit analysis, load
flow study and dynamic analysis.d) All options meet the technical requirement. Option 1 is
the best for reducing fault level and DC power losses.e) Option 3 provides the most cost saving.f) The challenge of FCLs is the equipment availability in
transmission level.
