Voltage Management on Low Voltage
Busbars
Linwei Chen
PhD Student in Electrical Energy and Power Systems
linwei.chen@postgrad.manchester.ac.uk
B4 Council Chamber, Sackville Street Building – 3rd Oct, 2014
LV Network Solutions Project – Dissemination Event
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Outline
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Project objectives
Modelling of voltage control devices and LV networks
Analysis of network site trial monitoring data
Voltage regulation studies
Network Capacity studies
Conclusions
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Project Objectives
 This project deployed a range of voltage management
methods and techniques across several distribution substations
within Electricity North West Limited.
 These technologies were assessed in terms of their ability to
effectively regulate line voltage in real-time in a safe and
economical manner.
 In addition, the ability of compensating devices to correct for
power factor and feeder power quality was also assessed.
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Options of voltage management in LV networks
 Voltage regulation devices
– Two distribution transformers with on-load tap changers (OLTCs)
(from MR)
– Two voltage optimisers (from powerPerfector Plus)
 Voltage/Power quality
– Two active harmonic filters (from ABB filters)
 Reactive compensation
– LV capacitors (from ABB)
 Energy storage device (through simulations)
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of Devices and Networks
 Active filter
 powerPerfector Plus unit
 Distribution transformer with OLTC
 LV network
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of Active Filter
 Model was developed in PSCAD/EMTDC based on the control
algorithm in [1]
K
Ia
Ib
Ic
p
p
Calculation
q
of p,q
Filter
q
Va Vb Vc
Calculation
of harmonic
current
PWM
control
Va Vb Vc
VaVbVc
LR
VDC
CR
Load
IGBT
[1] H. Fujita, and H. Akagi, “A practical approach to harmonic compensation in power systems - series
connection of passive and active filters,” IEEE Transactions On Industry Applications, VOL. 21, NO. 6, 1991.
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of Active Filter (cont.)
 Active filter in PSCAD
Harmonic load
IGBTs for PWM
Waveform plots
Calculation of p,q
Harmonic current calculation
© 2014 L. Chen - The University of Manchester
PWM control block
LVNS Dissemination Event, October 2014
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Modelling of powerPerfector Unit
 The unit was connected at the distribution transformer LV side
to regulate the voltage on one LV feeder.
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of powerPerfector Unit (cont.)
Ia2
Tap
Ia1
Ea
In
#2
E
#1
1.0
Ia1
A
V
Tap
In
#2
E
#1
Ia3
Ia3
#3
#3
Ea3
Ea3
Ia2
R=0
Tap
Ib1
Eb
#2
En
#1
C
A
B
1.0
R=0
Ib1
Ic1
Ec
#2
#1
0.6 [ohm]
Tap
Ib3
#3
#3
1.0
En
#1
C
Ib3
Tap
#2
A
V
Ic1
1.0
Tap
A
V
#1
Eb
10 [ohm]
B
1.0
Ec
10 [ohm]
A
0.6 [ohm]
Ea
10 [ohm]
1.0
0.6 [ohm]
 Model in PSCAD
#2
#3
#3
(a) Step down function
© 2014 L. Chen - The University of Manchester
(b) Boost function
LVNS Dissemination Event, October 2014
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Modelling of powerPerfector Unit (cont.)
 The powerPerfector Plus unit is designed to maintain a
stabilised output voltage for the load.
Voltage
Input Voltage
100V
99V
98V
96V
95V
Output Voltage
Time (t)
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
10
Modelling of Distribution Transformer with OLTC
 MR voltage regulator TAPCON 230 pro was installed to control
OLTC.
Control signal
Voltage regulator
TAPCON 230
Desired voltage
setpoint
Measured
transformer output
Analog and digital inputs
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of LV Networks
 Simulate six LV networks
Dunton Green
Howard St
© 2014 L. Chen - The University of Manchester
Edge Green Lane
Leicester Ave
Greenside Lane
Landgate
LVNS Dissemination Event, October 2014
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Modelling of LV Networks (cont.)
 Each network consists of several LV feeders.
Dunton Green
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Modelling of LV Networks (cont.)
 To study the performance of voltage management devices,
each LV feeder has been simplified and modelled in PSCAD.
Voltage profile of Leicester feeder
Voltage profile of Leicester feeder
(in OpenDSS)
(in PSCAD)
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
14
Network Site Trial Monitoring Data
 Active filter site trial
– Dunton Green substation
– Howard Street substation
 powerPerfector (pP) site trial
– Greenside Lane substation
– Edge Green Lane substation
 Distribution transformer with OLTC site trial
– Landgate substation
– Leicester Avenue substation
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Active Filter Site Trial
 Investigate the ability to filter out network harmonic currents
Filter switched off
© 2014 L. Chen - The University of Manchester
Filter switched on
LVNS Dissemination Event, October 2014
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powerPerfector Site Trial
 Assess the ability to decrease/increase feeder voltage
Step Down Mode
© 2014 L. Chen - The University of Manchester
Boost Mode
LVNS Dissemination Event, October 2014
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Distribution transformer with OLTC Site Trial
 OLTC had performed approximately 80 times in a 3 month
period
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Voltage Regulation Studies
 Assess the effectiveness of control devices on regulating
voltage
– Distribution transformer with OLTC
– LV capacitor
– Energy storage device
 Investigate the LV feeders with different load levels and
photovoltaic generator (PV) penetration
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Distribution Transformer with OLTC
 With large PV penetration, employ OLTC transformer to reduce
the voltage at the substation so that the voltages along the
feeder could be maintained within the limits.
-4% tap position
without PV penetration
© 2014 L. Chen - The University of Manchester
with PV penetration
LVNS Dissemination Event, October 2014
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Distribution Transformer with OLTC (cont.)
 The OLTC transformer is able to reduce or increase the
substation voltage under different network conditions.
at high PV outputs
© 2014 L. Chen - The University of Manchester
at reduced PV outputs
LVNS Dissemination Event, October 2014
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LV Capacitor
 The installation of capacitor banks on the feeder could produce
reactive power to compensate the voltage drops.
Installed at substation
© 2014 L. Chen - The University of Manchester
Installed at feeder mid-point
LVNS Dissemination Event, October 2014
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Energy Storage Device
 When the PV generation is high while demand is low, the
energy storage devices could be charged to absorb the excess
power.
without storage
© 2014 L. Chen - The University of Manchester
with storage installed
at mid-point
LVNS Dissemination Event, October 2014
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Energy Storage Device (cont.)
 The storage unit can be configured to absorb the excess power
generated by PVs and release the power during periods of
peak demand.
Charge mode
© 2014 L. Chen - The University of Manchester
Discharge mode
LVNS Dissemination Event, October 2014
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Network Capacity Studies
 Investigate which solution increases more network capacity
while maintaining the voltage level within the statutory limits.
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Conclusions
 Establish learning on a range of alternative techniques for
management of voltages on low voltage networks
 Deployment of new technology on the network for improved
voltage regulation and measurement of the effect on voltage
profiles in response to changes in demand
 Assessment of voltage management device effectiveness
 Investigate the changes in network capacity with different
voltage management techniques
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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Thanks for your time
© 2014 L. Chen - The University of Manchester
LVNS Dissemination Event, October 2014
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