Smart Power Distribution: A Case Study of Middleboro Industrial Park

This report analyzes the design of a smart power distribution network for an industrial park in the Middleboro estate. The study focuses on a ring-main distribution system, detailing transformer selection (132/11kV and 11kV/400V), VAR compensator implementation, and load shedding strategies. The report also addresses the integration of embedded generation, including solar PV cells, and the implementation of a SCADA system for network control. Technical analysis includes load flow determination and short-circuit current calculations. The report highlights the importance of load shedding conditions at various voltage levels and the operational considerations for island mode scenarios. The design incorporates theoretical research, technical findings, and practical considerations for a robust and efficient power distribution system. The report includes relevant tables and figures to support the analysis and recommendations.

Running head: SMART POWER DISTRIBUTION
Name of the Student
Name of the University
Course code
Date

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Executive Summary:
In the Middleboro estate a transmission and distribution network are needed to be built for
power supply in the factories within the 100-meter area. The technical equipment and
software design are given in this paper but it is limited to provide detail electrical calculations
and coding portions. The accepted design of network is chosen to be as a ring-main
distribution system which in turn will allow the high voltage operations with minimum
disruptions. Low voltage coupling is also provided for maintenance of the transformers;
however, installation of autotransformers is also needed to increase the sending end voltage
and to improve the voltage regulation. The study is limited to for determination of load flows
in the network and the exact fault levels in each installation for choosing the correct
equipment, however, some based on some assumptions some equipment is selected like
standard high voltage and low voltage switchgear, distribution boards and the SCADA
software.

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Table of Contents
Introduction:...............................................................................................................................2
Theoretical research:..................................................................................................................4
Selection of transformer:........................................................................................................5
132/11kV transformer specification:......................................................................................5
11kV/400 Volts step down transformer specification:...........................................................6
Selection of VAR compensator for embedded generation:........................................................7
Technical Analysis and findings:...............................................................................................8
Load Shedding condition:..........................................................................................................9
11KV/400 V level:...............................................................................................................10
400 Volt distribution network level:....................................................................................10
Factory level load shedding:................................................................................................10
Operation in Island mode:........................................................................................................10
Solar PV cells generation:....................................................................................................11
SCADA implementation:.........................................................................................................11
Conclusion:..............................................................................................................................13
References:...............................................................................................................................14
Introduction:
In the brownfield industrial Park, it is needed to provide electricity in the 400 volts range to
the 19 factories as illustrated in table 1. The supply is to be taken from a nearby 132 kV

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power transmission line by means of a 132/11kV step-down transformer. The fault level in
the bus bars of 132 kV line according to DNO is 200 MVA. Now, for the security of the
11kV line, furthermore, three 11 kV/400 V transformers are installed to provide 400 Volts
supplies into individual factories. Additionally, an embedded generation with some energy
storage device is needed to be installed to support the three transformers in case of power
failure. A model of Islanded operation or load shedding operation is also needed to be
installed to provide future development in the private industrial network. A SCADA system
will be implemented controlling the whole 11kv/400 V network.
Table 1: Loads in Factories
Factory Number Load in kW Power Factor
F1 1200 0.95
F2 1100 0.98
F3 1300 0.95
F4 to F8 (each) 800 0.8
F9 to F14 (each) 300 0.8
F15 to F19 (each) 400 0.85

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Fig 5: Design site layout
Theoretical research:
The theoretical research for the entire project is segmented into mainly five parts. At first,
suitable transformers are selected from a reputed manufacturer. Then for embedded
generation of power in the 19 factories, a suitable static VAR compensator is selected
accordingly. The next phase constitutes a proper plan of power generation when running in a
load shedding mode or in Island mode, i.e. in case of power failure an emergency power
generation system should be present to complete ongoing works in the factories to prevent
loss of raw materials and effort. The whole system should be automated and controlled by
some software and the using MATLAB for the programming of automation is the best option
as it is a high-level language which will reduce the lines of code and efficient response can be
obtained. The MATLAB code is then interfaced with some SCADA hardware for practical
implementation of the entire plan.
S/S

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Selection of transformer:
In the brownfield industrial park, the substation will be supplied from a 132-kV overhead
transmission line. Hence, a step-down transformer of 132/11kV will be installed in the
substation. Winder Power is a reputed transformer manufacturer in the United Kingdom and
provides transformer of different specification (Salodkar, Ghate & Kalwaghe, 2017). Hence,
a 132/11kV step-down transformer of the specified ratings will be selected from the above
transformer manufacturer company with the following specifications.
132/11kV transformer specification:
 Primary side voltage: 132 kV 3 phase delta
 Secondary side voltage: 11 kV 3 phase star
 MVA rating: 50 MVA
 Peak working ambient temperature: 40 °C
 Lowest working ambient temperature: -25 °C
 Ice loading: peak radial ice thickness is 12.5 mm.
 Earthing of the system: Based on the resistance and reactance of the supply line
(Banerjee, 2015).
 System frequency: 50 Hz.
 Maximum system continuous voltage: 12 kV (rms)
 Minimum withstanding lightning impulse: 95 kV.
 Short circuit current at rated voltage for symmetrical fault: 21.9 Amps.
 Minimum air clearance: 400 mm for line to neutral and 430 mm for phase to phase.
 Safety clearances: 2600 mm from the closest unscreened live conductor and 2400 mm
from closest point that is not at earth potential.
Now, from the primary transformer the supply voltage is stepped down to 400 V by three
Step down transformers of 11kV/400 V transformers.

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Fig 1: A typical 132/11 kV transformer
Source: ("Power Transformers & Distribution Transformers | Winder Power", 2018)
11kV/400 Volts step down transformer specification:
 Primary side voltage: 11 kV 3 phase delta
 Secondary side voltage: 400 V 3 phase star
 MVA rating: 3.15 MVA
 System frequency: 50 Hz.
 Peak working ambient temperature: 40 °C
 Lowest working ambient temperature: -25 °C
 Ice loading: peak radial ice thickness is 12.5 mm.
 Earthing of the system: Solid.
 High voltage tapping range: ± 5%.

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 Short circuit current at rated voltage for symmetrical fault: 10 Amps.
 Minimum clearance: phase to phase is 350 mm and phase to earth is 320 mm (Wang
et al., 2017).
Fig 2: A typical 11kV/400 V transformer
Source: ("Power Transformers & Distribution Transformers | Winder Power", 2018)
Selection of VAR compensator for embedded generation:
As the entire system is a high voltage electricity generation system where 132 kV is stepped
down 11 kV first and then 11kV to different low voltage side of 400 Volts power is
distributed, hence, some static VAR compensator is needed to provide reactive power in an
efficient way (Chandran, Sunderland & Basu, 2018). The function of the VAR compensator
will be to bring the system very close to unity power factor (Eremia, Gole & Toma, 2016).
The main two purposes of the VAR compensators are to regulate the 132-kV supply voltage
within 5% of the limit and to improve the power qualities in the loads installed in the

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factories. Hence, the selected VAR compensator for the network is PCS-9580 static VAR
compensation system.Features of PCS-9580 VAR compensator:
 Dynamic reactive source of power controlled by TCR, TSC, TSR and BSC
 System activity, stability and reactive power distribution can be optimized by RTDS
and PSCAD along with the Analog Simulation Environment (Luo et al., 2015).
 Filtration of harmful harmonics to provide power in fundamental frequency and
minimized dynamic loss of active power.
Technical Analysis and findings:
The real load value and the type of loads of the different factories inside the network are
specified and hence from that information the KVA rating of the loads and the short circuit
current rating of the loads can be calculated as given in table 2. The factories are assumed to
be running in steady state loads (Mujawar et al., 2016).
Table 2: KVA calculation of different factories
Factory
number
Load
(Kw)
Power
Factor
KVA
rating
Short circuit current (Isc
in kA)
F1 1200 0.95 1263.1579 3.157894737
F2 1100 0.98 1122.449 2.806122449
F3 1300 0.95 1368.4211 3.421052632
F4 800 0.8 1000 2.5
F5 800 0.8 1000 2.5
F6 800 0.8 1000 2.5
F7 800 0.8 1000 2.5
F8 800 0.8 1000 2.5
F9 800 0.8 1000 2.5

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F10 300 0.8 375 0.9375
F11 300 0.8 375 0.9375
F12 300 0.8 375 0.9375
F13 300 0.8 375 0.9375
F14 300 0.8 375 0.9375
F15 400 0.85 470.58824 1.176470588
F16 400 0.85 470.58824 1.176470588
F17 400 0.85 470.58824 1.176470588
F18 400 0.85 470.58824 1.176470588
F19 400 0.85 470.58824 1.176470588
Hence, the estimated total KVA rating of all the factories will be approximately 13981.969
KVA and the total short-circuit current rating will be 34.955 KA. Hence, if the three 11kV/
400 transformers are to be designed as equally loaded then the capacity of each of the
transformer must be at least 4660.656 KVA to meet the demand of the factory loads. It is also
assumed that no factories will be running in the overloaded condition that is factories will not
be using more than the load in KW as specified in Table 2.
Load Shedding condition:
One of the most important consideration is making the arrangement for Load shedding
condition that can happen primarily in three levels.
11KV/400 V level:
This level is the most critical level as shutting down this level will cause power disruption in
the entire network and in the factories (Gunawardana, Perera, & Moscrop, 2015). Hence, load

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shedding in this level is not recommended and if required then it must be done for very short
interval and all the users of factories must be notified before the shutdown.
400 Volt distribution network level:
Load shedding in this level will cause shutdown in specific selected factories. This is much
advantageous as this will not affect the production in all the factories and based on the
requirement some factories can be shut down for maintenance of large time.
Factory level load shedding:
Load shedding in this level is the most efficient type of shutdown as this will only shutdown
some sections in the factories. An example could be shutting down the warehousing system
of the network while maintaining the lighting system in the factories. Integration of this type
of shutdown require SCADA control in the network where load shedding can be performed
remotely to specific sections of some selected factories. However, the software
implementation can be costly and can be reduced to manual shutdown if required if agreed by
the management of the factories.
Operation in Island mode:
This is a situation when the connection of the main transformer to the grid line of 132 kV is
lost either by the planned or unplanned way. In this situation some sort of power generation
inside the factories or in some place inside the park is required to meet the immediate power
consumption of the factories is known as running in Island mode (Piyabongkarn, Buck &
Dimino, 2016). Now, the maximum amount of power that can be required if all the factories
are running in maximum load will be 13981.969 KVA and hence the power generation
system need to be able to generate this amount of power. Now, it is expected that not all the
factories are running at the maximum loaded condition at the same time and hence generation
can be reduced accordingly. Employing load shedding in factory level or in 400 Volt network

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level, the amount of Island mode generation can also be reduced.Embedded generation
options:
The power generation for Island mode can be done from several methods. Considering the
worst-case scenario of generation of 13981.969 KVA at a time every method of generation
must be present in the site. The different methods are given below.
Solar PV cells generation:
A PV panel can produce approximately 1000 watts per square meter but the efficiency of the
panel is only 20% i.e. only 200 watts can be extracted from one square meter (Das &
Agarwal, 2015). The factories 1, 2 and 3 which are around 20000 m^2 each can produce a
power of 4 MVA each and hence a total of 12 MVA can be produced. This meets over 90%
of the total peak demand of power of 13.98 MVA.
Remaining amount of power can be generated by installing wind power turbine, gas turbine
or diesel generator.
SCADA implementation:
The SCADA representation of the entire network is given below. The green lines indicate the
live sections of the network, where, the red line or components are either dead or sections
with issues (Almas et al., 2014). The portions that are in the state of N/O (not working) are
shown in red and those do not affect the network. The low voltage substation C is represented
in red as it is open.