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1. INTRODUCTION TO K-2 & K-3 GRIDS
1.1 GRID DESCRIPTION
1.2 SAFETY-RELATED LOAD
1.3 ACCEPTANCE
2. OFFSITE POWER SYSTEMS
2.1 500kV Network
2.2 132kV Power System
2.3 LOAD FLOW STUDIES
3. AC POWER SYSTEMS
3.1 TYPE OF UNIT AUXILIARIES TO BE POWER SUPPLIED (GENERAL DESCRIPTION)
3.2 ELECTRICAL POWER SUPPLY FOR POWER STATION AUXILIARIES
3.3 DESCRIPTION OF THE 6.6KV DISTRIBUTION SWITCHBOARDS
3.4 380V SWITCHBOARD CONFIGURATION
3.5 ELECTRICAL POWER RESUPPLY DURING OUTAGE (ETR)
3.6 TRANSFER OF NORMAL ELECTRICAL POWER SUPPLIES AFTER FAULT DETECTION
3.7 EMERGENCY SUPPLY TO AUXILIARIES FROM ONSITE POWER SOURCES (DIESEL GENERATOR SETS)
3.8 TOTAL LOSS OF OFFSITE AND ONSITE ELECTRICAL POWER SUPPLIES ON A PLANT UNIT, RESUPPLY BY EMT AND EES SYSTEM
3.9 TESTS RELATIVE TO THE AC SYSTEMS
4. DC Power Supply Systems
4.1 CONFIGURATION AND OPERATION
4.2 SAFETY ANALYSIS OF DC POWER SYSTEM
5. Emergency Diesel Generator Set and Site Supplementary Power
Supply Diesel Generator Set
5.1 THE SITE SUPPLEMENTARY POWER SUPPLY DIESEL GENERATOR SET (EMS)
5.2 INSTRUMENTATION, CONTROL AND PROTECTION RELATIVE TO EMERGENCY DIESEL GENERATOR SET
5.3 VITAL INSTRUMENTATION AND CONTROL POWER SUPPLY
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1.INTRODUCTION TO K-2 & K-3 GRIDS
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1.1 GRID DESCRIPTION
The new Karachi Nuclear Power Plant (K-2/K-3) will be constructed at site located
near K-1, in the southern coastal region of Pakistan on Arabian Sea.
The power plant is connected with two different power sources:
i. 500kV for the power transmission and normal plant startup or shutdown.
ii. 132kV for the auxiliary supplies of the auxiliaries necessary for shutdown and
safety.
These two plants will deliver the generated power to WAPDA system through a common
switchyard (for K-2 and K-3), connected to Matiari grid by two 500kV double circuit
transmission lines.
The following interconnection scheme has been proposed for reliable dispersal of power
from future coastal power projects (K-2 & K-3) to the National Grid System under normal
and single line contingency conditions:
i. Two 500kV HVAC D/C transmission lines, approx. 200 + 200 =400 km long, on
twin bundled Greeley conductor from K-2/K-3 power plants to Matiari;
ii. ±600 kV H\TDC bipole (2x 2000 MW capacity), approx. 1000 km long, on six
bundle Bitterroot conductor from Matiari to Lahore South with HVDC convertor
station on both ends.
It is important to highlight that the interconnection of 1200 MW imported coal plant, lying
in coastal area nearby, has been proposed in one of the four 500kV circuits from K-2/K-3
power plant to Matiari.
Gross and Net Capacity of proposed Coal Plants
The gross and net capacity of these projects is given as under:
i. Gaddani Imported Coal project (Gross Capacity: 5x1320 = 6600 MW & Net
Capacity: 5x1200 MW = 6000 MW);
ii. Bin Qasim Imported Coal Project (Gross Capacity: 1320 MW & Net Capacity:1200
MW);
iii. Jamshoro Coal fired project (Gross Capacity: 1320 MW & Net Capacity:
1200MW);
iv. Thar Coal project (Net Capacity: 1200 MW);
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v. Maximum generation of the existing thermal power plants at Hubco, Jamshoro,
Kotri, Uch- 1, Uch-2 and Guddu power plant in south;
vi. Wind power plants generation with total gross capacity of 1756 MW in the
southern part of the system. The wind power has been planned to be evacuated to
the 132kV and 220kV network underneath Jamshoro. 8.1.2 Onsite Power Supply
Three sources of offsite power are provided to supply preferred power to the onsite
Class 1E systems through 500kV switching station and 132kV auxiliary switching station.
The main features of the distribution network are as follows:
i. The generator circuit breaker connections between the generator and the main
transformer enables to cut off fault current.
ii. The auxiliaries for each Unit are divided into groups depending on their safety and
operational function, including consideration of all the different operational
situations and foreseeable abnormal situations.
iii. The two Units are electrically independent. In case of an accident, the faulty Unit
must be able to respond to the accident regardless of the condition of the other Unit.
For this reason, each Unit has two independent diesel generator sets.
1.2 SAFETY-RELATED LOAD
Power supplies to the auxiliaries are designed to meet requirement of Unit availability
and, more importantly, of nuclear safety. Nuclear safety depends upon various factors on
the electric supply conditions of certain auxillary systems of NSSS.
The design of the electric power system has following features.
i. Electric power sources
The electric sources include two offsite power sources separately routed from the
main grid with common routing near the power plant due to the geographical
arrangement. Two onsite sources consisting of 100% redundant diesel generator
sets.
ii. Electric power supplies
The electric power supply system consists of two identical trains. These trains are
independent and are normally supplied by one of the offsite sources (the second source
ensures redundancy) and are backed up by the onsite sources in the event of main grid
failure.
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1.3 ACCEPTANCE
Power supplies have been designed based on the following criteria:
- They comprise two physically independent systems (not necessarily separately
routed) to ensure that simultaneous failure is minimized.
- The 132kV auxiliary power source is supplied by substation nearby;
- The quality of both sources is such that the auxiliaries supplied can be operated
or be started as soon as they are transferred from one source to the other.
- One supply for each of the two safeguard trains;
- No interconnections between trains of separate Units;
- Each power train supplies the electrical auxiliaries of each independent train of
the redundant mechanical systems (physical separation), so that loss of one
train does not lead to a loss of functions.
References
[1] HAP 102-2004, Safety Code on Nuclear Power Plant Design
RCC-E Design and Construction Rules for Electrical Components of nuclear Island
2.OFFSITE POWER SYSTEMS
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The Nuclear power plants (K-2/K-3) will be connected with two independent offsite power
sources, one at 500kV and other at 132kV in National Transmission and Dispatch Company
(NTDC) and Karachi Electric Supply Corporation (KESC) System respectively.
Each Unit (K-2/K-3) will generate power at 24kV and this power will be stepped-up to
500kV by the Main Transformers (MTs) independently. The 500kV network will also
supply power for normal plant startup or shutdown.
The 132kV network will be used as a standby power supply source.
2.1 500kV Network
The power generated by the plants (K-2/K-3) will be delivered to NTDC System through a
500kV switchyard (common for K-2 and K-3), connected via two 500kV double circuit
transmission lines from K-2/K-3 to Matiari.
For dispersal of power from K-2/K-3, 3x500kV circuits to Matiari will be installed, which is
about 200 km from plant site and lx 500kV circuit for looping in and out on Bin Qasim
Power Project which is about 140 km from plant site will be installed. The 500kV
electrical system is classified as Non-Class 1 E System.
The 500kV system constitutes a preferred source (offsite) for supplying power to plants
auxiliaries including Class 1E loads. The system will supply electrical power for start up,
safe shut-down as well as operation of emergency systems and the engineered safety features,
in accordance with IEEE 765-2006 standard.
The 500kV transmission lines from Matiari and Bin Qasim Power Project, and the 132kV
system will be physically separate and independent from each other, and designed in such a
way that the probability of simultaneous faults in the offsite power supply circuits (500kV
and 132kV system), due to operating conditions, postulated accidents and atmospheric
conditions is reduced to minimum.
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The 500kV system will supply power for start-up, emergency reactor shut-down,
containment isolation, reactor core cooling, and containment and reactor heat removal and all
those services required for preventing significant release of radioactive material to the
environment in accordance with IEEE 765-2006 and GB/T 13177-2008 standard.
The 500kV system will be provided with the instrumentation necessary for the
indication and continuous monitoring of its operational status, to ensure that any change in
the system, which could impair its functions is detected by the operator in the control room
in accordance with IEEE 765-2006.
All the circuit breakers of the 500kV system will operate manually/automatically from the
grid control building of K-2/K-3.All the components of the 500kV system will be designed
and installed in accordance with the requirements of latest applicable IEEE/ANSI, IEC and
other applicable standards .The limiting conditions for operation (LCOs) will be met in
accordance with USNRC Regulatory Guide 1.93-2012.
2.2 132kV Power System
The 132kV power system will act as a standby offsite power source and provide power
to the required plant emergency loads for safe shut-down of the plant(s) in case of
unavailability of 500kV network and outage of main generator(s).
The 132kV power system is classified as Non Class-i E System .The system will be
designed to be available within a few seconds following a loss of coolant accident to assure
that the core cooling, containment integrity and other vital safety functions are maintained.
The 132kV system will be designed to facilitate the periodic inspection and testing of
important areas and features - such as wiring, insulation, connections and switchboards to
assess the continuity of the systems and the condition of their components in accordance
with 1 OCFR5O Appendix A, General Design Criteria No. 18.
The 132kV power system will have sufficient capacity to provide the required loads during
start-up and the normal operation of the plant .A 500kV switchyard will be constructed
with all the required auxiliaries for dispersal of power from Units K-2/K-3 to Matiari and
Bin Qasim Power Project as shown in Figure.
The criterion of operation is as under:
a) Voltage Limits: ±5% under normal and ±10% under contingency conditions.
b) Transmission: 100% under normal and N-i contingency line loading conditions
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2.3 LOAD FLOW STUDIES
2.3.1 Peak Load January 2021
Load flow study for the peak load of January 2021 under normal system condition has been
carried out with the induction of 2x 1100 MW, K-2 and K-3 nuclear power plants and is
attached as Exhibit #1. As per load flow study, the power flows on the circuits emanating
from K-2/K-3 plants and in their vicinity are as under:
Transmission Line Power Flow
K-2/K-3 - Matiari three 500kV S/C 3 x 755.7 MW
K-2/K-3 - Bin Qasim 500kV S/C 232.6 MW
Bin Qasim - Matiari 500kV S/C 967.4 MW
Matiari - Lahore-South ±600 kV HVDC bipole 2 x 1650 MW
Matiari - Jamshoro S/C 205.1 MW
Matiari - Moro S/C 523.4 MW
Matiari - Gadani D/C 2 x 175.8 MW
Gadani - Lahore-South ±600 kV HVDC bipole 2 x 1650 MW
Gadani - Faisalabad-West ±600 kV HVDC bipole 2 x 1650 MW
Jamshoro - Dadu (circuit #1) 522.2 MW
Jamshoro - Dadu (circuit #2) 579.5 MW
Dadu - Shikarpur (circuit #1) 358.1 MW
Dadu - Shikarpur (circuit #2) 396.0 MW
Lahore South - Lahore Old (circuit #1) 764.4 MW
Lahore South - Lahore Old (circuit #2) 1104.0 MW
Lahore South - Lahore North D/C 2 x 1118.4 MW
Lahore South - Gujranwala S/C 850.8 MW
Lahore South - Sahiwal S/C 377.0 MW
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2.3.2 Peak Load Aug/Sep 2021
Transmission Line Power Flow
K-2/K-3 NPPs - Matiari three 500kV S/C 3 x 755.8 MW
K-2/K-3 NPPs - Bin Qasim 500kV S/C 232.3 MW
Bin Qasim - Matiari 500kV S/C 967.2 MW
Matiari - Lahore-South ±600 kV HVDC bipole 2 x 1650 MW
Matiari - Jamshoro S/C 42.9 MW
Matiari - Moro S/C 554.2 MW
Matiari - Gadani D/C 2 x 241.7 MW
Gadani - Lahore-South ±600 kV HVDC bipole 2 x 1700 MW
Gadani - Faisalabad-West ±600 kV HVDC bipole 2 x 1700 MW
Jamshoro - Dadu (circuit #i)575.9 MW
Jamshoro - Dadu (circuit #2) 638.8 MW
Dadu - Shikarpur (circuit #i) 370.2 MW
Dadu - Shikarpur (circuit #2) 409.8 MW
Lahore South - Lahore Old (circuit #i) 788.4 MW
Lahore South - Lahore Old (circuit #2) i i38.4 MW
Lahore South - Lahore North D/C 2 x 875.5 MW
Lahore South - Gujranwala S/C 55i.5 MW
Lahore South - Sahiwal S/C 877.5 MW
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3. AC POWER SYSTEMS
3.1 TYPE OF UNIT AUXILIARIES TO BE POWER SUPPLIED (GENERAL
DESCRIPTION)
The power station auxiliaries are divided into four types:
a) The 'plant unit auxiliaries': those auxiliaries necessary for normal operation of the
plant unit. When the unit is shut down, the auxiliaries can be shut down. For
example: Reactor coolant pumps, Auxiliary equipment of the unit, circulating water
pumps, feed water pump, Condensate pump.
b) The 'permanent auxiliaries': Which are used more particularly during plant unit
shutdown, some are used during unit operation. For example: Compressed air
production and distribution system, Electrical equipment of the nuclear auxiliary,
Electrical equipment of the fuel building, Auxiliary steam distribution system,
Electrical equipment of the PX building
c) The 'emergency power-supplied auxiliaries': which are necessary from a nuclear
safety point of view and protect the important plant unit equipment, including the
safeguard auxiliaries and the safeguard important equipment auxiliaries. The
safeguard auxiliaries: Which can protect, limit and reduce the leakage of radioactive
materials to environment. For example: Reactor Coolant system, Containment Spray
system, Containment Cleanup system, Auxiliary Feed water system
d) The 'site common auxiliaries': Which are the general auxiliaries common to the two
plant units and have no relation to the electrical power generation as well as they
will not affect the unit operation.
3.2 ELECTRICAL POWER SUPPLY FOR POWER STATION AUXILIARIES
a) Power supply for the 'plant unit auxiliaries':
- When the unit is in normal operation, the auxiliaries are supplied from the
generator by the unit step down transformers;
- When the unit is shut down, the auxiliaries are supplied from the main offsite
power supply source by the unit step down transformers.
b) Power supply for the 'permanent auxiliaries':
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- In normal operation, the auxiliaries are supplied from the generator by the unit
step down transformers; when the unit shut down, the auxiliaries are supplied
from the main offsite power supply source by the main transformer and unit
step down transformers;
- When the unit step down transformers fail, it can be supplied from the auxiliary
power source by stand-by auxiliary transformers.
d) Power supply for the 'site common auxiliaries'
The electrical equipment which used to supply the electrical power to all the auxiliaries
mentioned above are designed and installed according as the rules in specialty.
The power station auxiliaries required for normal operation are supplied by 6 group 6.6kV
distribution switchboards: ESA, ESD, ESE and ESF for 'plant unit auxiliaries'; ESB and
ESC for 'permanent auxiliaries'.
The choice of incoming cables and breakers which connect with two unit step-down
transformers must ensure the power supply for any power station auxiliaries at the same time
in any operation.
The power supply changeover from unit step down transformers to stand-by auxiliary
transformers is a slow, sequential and automatic transfer mode. A 1.5 seconds time delay
allows for the magnetic motor flux to decay. The changeover usually occurs automatically
and it can be performed manually either from main control room (MCR) or remote shutdown
station (IRS).
When all of the offsite power sources fail, the EMA and EMB are fed by EDG sets. An under
voltage set at 0.8 Un (time-lagged 0.9s) has been detected on EMA and EMB's busbars is
one of the condition which initiates EDG sets start
3.3 DESCRIPTION OF THE 6.6KV DISTRIBUTION SWITCHBOARDS
The normal and emergency 6.6kV distribution switchboards are identical.
The circuit breaker cabinets/panels are fitted with circuit breakers which rated current is 31
50A, 1 600A or 1 250A. The contactor cabinets/panels feed the power to 6.6kV auxiliaries
which rated power less than 750kW (rated current less than 80A). All the fuses' rated current
is 250A of all fused contactors.
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- Train A switchboard: identified by an orange label, engraved in white;
- Train B switchboard: identified by a green label, engraved in
white.
All of the 6.6kV distribution switchboards are installed in Safety Buildings, train A
switchboards are installed on level 1 7.OOm of NL building, train B switchboards are installed
on level 1 7.50m of NR building. It is physically separated of two trains because of the
installation in different buildings.
The electrical rooms for these 6.6kV distribution switchboards are designed against water
ingress, flood, missiles and seismic events for the connection between transformers and
switchboards.
3.4 380V SWITCHBOARD CONFIGURATION
The 380V switchboards are fed by the 6.6kV/400V transformers. The 6.6kV/400V
transformer is fit together with 3 80V switchboards and fed by fused contactor outgoing
circuit of 6.6kV switchboard.
The 3 80V auxiliaries of the normal network are distributed between several functional
switchboards which are supplied from the 6.6kV switchboards.
380V distribution switchboards used for BOP are supplied by busbar ESH and ES!.
The rating of the switchboards and 6.6kV/400V transformers and the distribution
arrangement enable all the emergency power-supplied auxiliaries to be fed adequately
whatever the operating condition might be.
3.4.1 Nuclear Island 380V Switchboards
The 380V normal and safeguard switchboards used for Nuclear Island auxiliaries are
identical. The following table shows the switching devices used, with their relevant
protections:
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Type of equipment Protections
Contactors Thermal and fuse (or breaker)
Circuit breakers Magnetic and thermal
Reversible contactors Thermal and fuse (or breaker)
Each switchboard is fed via a dry type, 6.6kV/400V, 800kVA transformer with adjustable off
circuit taps at ± 2.5% .
3.4.2 Conventional Island 380V Switchboards
The switchboards are used for the turbine essential auxiliaries and the standby lighting for the
Conventional Island and Balance of Plant. The switchboards are used under emergency
conditions and are fed from Nuclear Island switchboard EMA (power train A).
The following table shows the switching devices used with their relevant protections.
Type of equipment Protections
Contactors (motors < 50 kW) Fuse (or breaker)and Thermal
Contactors (motors> 50 kW) Fuse (or breaker)and Thermal
• •
Each non-emergency power-supplied switchboard is fed via a dry type, 6.6kV/400V,
630kVA or 800kVA transformer with adjustable taps at ±2.5%.
3.5 ELECTRICAL POWER RESUPPLY DURING OUTAGE (ETR)
During 6.6kV or 380V switchboard's maintenance, the ETR system enables to reenergize
the 380V auxiliaries.
Description of the ETR system
- 380V AC equipment connected with EED
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- 380V AC equipment connected with ERA
- 110V DC equipment connected with EDG
- Uninterrupted 220V AC equipment conneted with ERI
3.6 TRANSFER OF NORMAL ELECTRICAL POWER SUPPLIES AFTER FAULT DETECTION
The detection of a network fault, as well as the actions taken by the turbo generator set
protections, leads to the following operating situations:
a) In case of mechanical faults or internal electrical faults of main generator, then
the main generator shut down, the generator circuit breaker trip. The ESA, ESD,
ESE, ESF can be supplied by main offsite power source through main
transformer;
b) The network faults cause the opening of the 500kV circuit breaker. When the
house loading operation has been successful, the ESA, ESD, ESE and ESF can be
supplied by main generator through generator circuit breaker and two unit
stepdown transformers;
The house loading is initiated by the detection of 'low rotate speed of reactor coolant pump',
when the voltage drops rapidly. However, when the reactor coolant pumps maintain their
speed, but the other motors might be tripped, the house loading order is initiated by a voltage
drop criterion.
The voltage must recover according to RCC-E (C 2133 B 'General Unit Auxiliary Restart), or
an emergency shutdown signal is given, which leads to a turbine trip and the opening of the
generator circuit breaker.
3.7 EMERGENCY SUPPLY TO AUXILIARIES FROM ONSITE POWER SOURCES (DIESEL
GENERATOR SETS)
Each of the two diesel generator sets providing internal emergency electrical power supply is
able to fulfill the following functions:
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(a) In case of a loss of the external power sources, to supply the emergency power-
supplied auxiliaries and enable a safe shutdown of the plant Unit without damage
to the equipment, for instance, to ensure the cooling of the reactor.
(b) In case of loss of the external power sources and with a simultaneous reactor
coolant accident (such as a loss of primary coolant), to supply without any time
limit for the reactor core emergency cooling.
For this reason, a load shedding and reloading program is provided to perform the following
functions:
The rating of the diesel generator set is based on the power balances occurring after three
types of accidents, all of them causing the switchover to the diesel generator set, and which
involve automatic shutdown of the plant Unit. The three types of accidents are:
a) Loss of voltage signal
b) Loss of voltage and safety injection signals.
c) Loss of voltage plus safety injection plus high-high pressure in the containment.
One diesel generator set supplies the 6.6kV EMA busbar; the other diesel generator set
supplies the 6.6kV EMB busbar. Both, EMA and EMB supply the safeguard auxiliaries.
These auxiliaries are systematically redundant. Stopping the diesel generator set is only
possible locally after resetting from the control room.
3.8 TOTAL LOSS OF OFFSITE AND ONSITE ELECTRICAL POWER SUPPLIES ON A PLANT
UNIT, RESUPPLY BY EMT AND EES SYSTEM
In case of total loss of offsite and onsite electrical power supplies on a plant Unit, different
means are provided.
For the short term, the EES system is used giving enough energy to the test pump and other
actuators necessary to keep the plant Unit on a safe condition.
For the long term and for the resupply of emergency-supplied switchboards the following
means are provided, in decreasing order of priority:
a) Resupply from the network;
b) Resupply from the plant Unit diesel generator sets;
c) Resupply from the site supplementary diesel generator set.
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The EES system is composed of two SBO diesel generator sets (800kw, EESO 1
OAP,EESO 11 AP) for per plant unit, one SBO diesel generator is standby for the other.
In the event of a simultaneous loss of voltage on the emergency power-supplied busbars
(EMA and EMB), EESO1OAP of this plant Unit starts up automatically and supplies the
hydrotest pump control cabinet (EESOO1AR) through EESO1OAR. Then the RIS test pump
automatically starts up and supplies water to the reactor coolant pump seals at the flowrate of 6
m3/h.
3.9 TESTS RELATIVE TO THE AC SYSTEMS
a) In-factory checking. Earthquake resistance capability
b) Checking and testing during commissioning
c) Checking and testing during operation
The general, practice is that the Class 1E items of equipment are not designed differently
from other items of equipment which have to perform a function connected to the process.
All these items of equipment are designed according to the technical specifications issued for
each type of electrical equipment and are relative to:
a) Motors (motor size, minimum accelerating voltage, motor starting torque, motor
insulation, temperature monitoring devices);
b) Motor valve actuators (motor size, minimum accelerating torque, coupling, motor
circulation);
c) 6.6kV power cables;
d) 1000 V power cables;
e) MV/LV distribution transformers.
3.9.1 ELECTRICAL POWER SUPPLY SAFETY ANALYSIS
The following analysis proves that the electrical power supply and distribution network
complies with all requirements relating to offsite power supplies and onsite AC power
supply:
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a) All permanent and emergency power supplied auxiliaries (for safety and safeguard
purposes) may be supplied from two external power
b) The electrical power is supplied by two, almost independent (500kV and 132kV)
networks via the plant switch-yard
c) The high-voltage, medium-voltage, and control supply network has been designed
so that it is possible to come back to the available source of supply despite the
downgraded condition of the network ;The following steps are taken to reduce the
probability of total loss of the electrical power supply sources as a consequence of
loss of power generated by the plant Unit, opening of the generator circuit
breaker ,loss of power coming from the offsite 500kV network house loading ,loss
of power supplied from onsite sources.
e) Each safeguard train is powered by the non-safety electrical distribution system
which has access to the main generator and two offsite networks.
f) In normal operation, there is no interconnections between the redundant safety
power trains of the same plant Unit;
g) Each power train supplies the electrical auxiliaries of the same independent train
of the redundant mechanical systems (physical separation), so that loss of one
power train does not lead to a loss of function;
h) Each busbar supplying a single train is provided with both offsite power supplied
and a separate onsite power supply;
i) The diesel generator sets are started automatically
j) Changeover of the emergency power-supplied auxiliaries from the offsite to the
onsite sources is automatic with loss of voltage on the busbars; the return to
normal power and subsequent diesel shutdown is manually controlled.
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4. DC Power Supply Systems
The DC power systems supply all the control and signal systems and the vital, permanent,
and classified 220V AC production, through DC/AC inverters (Figure 8.3-3).
Several independent DC systems are provided as follows:
a) The 220V DC network: ETU, which feeds the three inverters of system EAE;
b) The 110V DC networks:
EDA (train A), EDB (train B), EDG and EDP, feed in particular the control
circuits of contactors and circuit breakers and the EAG, EAH, EAF, EAP DC/AC
inverter.
c) Two 220V DC networks:
ETE (train A) and ETF (train B) which supply the valves, instrument and control
device relevant with passive safety system.
Train A safety related actuators' control are supplied by train A DC power and
Train B safety related actuators' control are supplied by train B DC power.
The turbine direct-current auxiliaries are fed by a specific 220V DC network
(ETC).
4.1 CONFIGURATION AND OPERATION
The physical identification color of train A is orange, train B is green, and the others are
colorless.
The independence criterion for DC system is following,
Each DC system includes:
a) One lead-acid battery;
b) One (for system EDP) or two battery chargers ensuring the battery charging and
the normal feeding of the consumers;
c) One distribution switchboard with incoming & outgoing circuit-breakers.
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Each distribution switchboard includes:
a) One protected busbar;
b) Incoming and outgoing breakers and switches;
c) Control and signal relaying systems.
The NI DC system relevant equipment are located in electrical rooms of electrical building
(LR) and safety building (SR) separately
Battery chargers, inverters, and switchboards are installed at level +8.50m of LR and SR
buildings, batteries are installed at level +4.80m of LR and SR buildings in order to shorten
distance with related switchboards so that reducing the voltage drop and possibility of fault
in cables.
4.2 SAFETY ANALYSIS OF DC POWER SYSTEM
The safety analysis of DC power system is following RCC-E 2005 C 1440.
a) The auxiliaries and their DC equipment are supplied by the busbars associated in
such a way that loss of electrical power on one train of auxiliaries does not affect
equipment on another train;
b) Each redundant DC power source consists of a battery and one or two battery
chargers and is connected to the same power train of emergency AC power supply
during normal operation;
c) The sizing criteria of DC power supply are also met. If the AC power supply to the
battery chargers is interrupted for one hour, the energy stored by the batteries is
sufficient to ensure adequate power to operate equipment and necessary
disconnecting devices, the 72h DC and UPS power system can ensure the need of
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5. Emergency Diesel Generator Set and Site
Supplementary Power Supply Diesel Generator Set
The diesel generator sets is provided with an engine and an alternator, and one alternator is driven by
one engine. Each generator set is fitted with an electronic speed regulation system.
Each cylinder is supplied by a separate fuel injection pump; failure of a single injection pump will
not cause shutdown of the diesel generator set.
Each generator is designed to be capable of withstanding the following faults:
a) Three-phase or two-phase short-circuits at the generator terminals due to an external fault.
b) Over speed operation
c) Over voltage
Ventilation of the diesel generator set room is designed so that the temperature of the room will not
exceed 49°C.
5.1 THE SITE SUPPLEMENTARY POWER SUPPLY DIESEL GENERATOR SET (EMS)
EMS system is consisting of site supplementary power supply diesel generator set, and it does not
perform the safety related function.
The site supplementary power supply diesel generator set shall be connected to the relevant
emergency distribution boards (EMA, EMB) system by EMT system.
The diesel generator sets for train A and train B are installed in two separate buildings:
a) One nearby electrical building (power train A, EMP);
b) Other nearby fuel building (power train B, EMQ).
The site supplementary power supply diesel generator set and its auxiliary systems concerning fuel
oil, cooling, starting, lubrication, are installed in another separate buildings on site.
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The general characteristic of diesel engine and generator for the site supplementary power are to be
determined .The diesel buildings are not designed to withstand plane crashes due to the small target
area of these buildings and the shadowing effect of other buildings, and thus a low probability of
occurrence
5.2 INSTRUMENTATION, CONTROL AND PROTECTION RELATIVE TO EMERGENCY DIESEL
GENERATOR SET
To monitor the operability of EDG, the instrumentation devices on local panel include:
voltmeter ,ampere meter ,frequency ,meter ,wattmeter ,varmeter ,excitation voltmeter and excitation
ammeter
In emergency situation, diesel generator may actuate on
a) Over speed (automatic);
b) Voltage loss (automatic);
c) Emergence manual shutdown.
Excluding emergency operation, tripping of the diesel generating set occurs for any of the following:
Electrical protection may actuate i-e differential, overload, overcurrent,loss of field, reverse power,
overvoltage , undervoltage ,over frequency ,under frequency,stator earth fault ,generator winding
temperature ,over speed ,excitation fault and manual emergency.
The engines protection may damage i-e Cooling water jacket high-high temperature ,Lube oil high
temperature ,Exhaust gas high/low temperature ,Low level of heating water jackets in the
system ,Low level of main fuel storage tank and a daily tank ,Emergency air valve closed
5.3 VITAL INSTRUMENTATION AND CONTROL POWER SUPPLY
a) A charger fed by a 380V AC emergency-supplied switchboard
b) An inverters of 10 kVA for each power supply;
c) A static transfer switch, loads will be transferred to bypass regulating transformer while
inverter loses its AC power;
d) An AC switchboard;
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