Operation of UPQC with PV for Power Quality

Paper Tittle: Operation of Unified Power Quality Conditioner with Photovoltaic Arrays
Paper ID:12
Session ID: SD8
Presented by: Dr. Alok Jain
Co-Authors: Kaibalya Panda and Suman Bhullar
IEEE IAS GLOBCONHT 2023
2023 IEEE IAS Global Conference on Renewable Energy and Hydrogen Technologies
An IEEE IAS 100% Financial Sponsored Conference
March 11-12, 2023 | The Maldives National University Male City Maldives

Contents
 Introduction
 PV-UPQC System
 Control Scheme for Series Active Power Filter
 Control Scheme for Shunt Active Power Filter
 Result Analysis
 Conclusion
 References
GlobConHT 2023 Date: 11-12 March 2023

INTRODUCTION
 Power Quality (PQ) is the standard according to which the system voltage,
frequency, and waveforms of the power supply framework adjust to established
specifications.
 It can be characterized as consistent supply voltage and frequency within the
endorsed range and waveforms free from harmonics.
 The issues with power quality are meticulously defined as “any issues in voltage,
current, or frequency, the outcome of which is the disoperation or failure of
customer’s equipment.”
 Photovoltaic-based Unified Power Quality Conditioner (PV-UPQC) is one of the
custom power devices widely employed for power quality improvement.
 A simplified control strategy is proposed for the PV-UPQC system with the
objective to regulate the dc-link voltage, compensate the harmonics in grid current,
and provide suitable control during a sudden change in the grid side or load side.

PROPOSED PV-UPQC SYSTEM
 Fig 1 shows a system configuration of a 3-
phase PV UPQC grid-tied system.
 UPQC is one of the prominent device to
improve the power quality such as voltage
sag, voltage swell, disturbance, etc.
 It has also the capability to address the issue
the low-order harmonics generated from the
type of loads.
 It comprises a shunt APF and a series APF,
which combined provide power quality
compensation.
 Both APFs are voltage source inverters that
need to be controlled by producing suitable
reference current that takes into account any
disturbance in the grid side as well as in the
local loads.
Fig. 1 Detailed configuration of UPQC

 The series APF supports compensate for the supply disturbances
(including harmonics, sag, swell, and flickers).
 The shunt APF converter compensates for the load current distortions
(caused by harmonics, imbalances, etc.) and reactive power
requirement of demands.
 Apart from this, the dc-link is fed from the PV source and feeds active
power to the grid.
 A dc-link voltage regulator is employed in the proposed system
which regulates the dc-link voltage using the simple PI controller.
 The central UPQC controller integrated both voltage and current
control for shunt and series APFs respectively. This enables proper
active and reactive power control in the system.
 The reference signal for the voltage controller is taken from the grid
voltage whereas, the reference signal for the current controller is
taken from the load side current.
 Inductive filters are connected before feeding power from the APFs to
the grid.

Control Scheme for Series Active Power
Filter
 Series compensator of UPQC may be
suitable for mitigation of voltage-related
problems like sags, swells, harmonics,
etc. in the power distribution system.
 To achieve this, the series compensator
may be operated in UPQC-P control
mode.
 In this mode, the required series voltage
(to maintain the reference load voltage)
obtained is injected in phase with the
supply voltage.
 In this work, the control block diagram
of the series compensator is
implemented in MATLAB/Simulink as
shown in Fig 2.
Fig. 2 Control block of the series compensator

Control Scheme for Shunt Active Power
Filter

Fig. 3 Control block diagram of shunt APF

RESULT ANALYSIS
PV-UPQC SIMULATION PARAMETERS
Source
Voltage 220Vrms 50 Hz
Distribution Line 5Km, 0.0123 Ω/Km,
0.93e-4H/km
DC-Link Capacitor C1=2000µf
Shunt Inverter
Filter L, R 1.5 mH, 10 Ω
Switching Frequency. 10kHz
Series Inverter
Switching Frequency. 10kHz
Filter C, R 100µF, 10 Ω
PV Array Power 2kW

Case 1: Normal Operation Balanced Source
voltage with Linear Loads
 Under balanced supply voltage and fixed
load condition, Fig. 4(a) & (b) depicts the
source voltage and current, respectively.
 The three-phase source voltages are not
exposed any change and thus three-
phases are balanced.
 PV panels are also operated at a constant
irradiation.
 Fig. 5 show the PV voltage and currents.
It is also clear that the dc-link voltage is
tracked accurately and quickly without
any error.
Fig. 4(b) Source current during normal operation
Fig. 4(a) Source voltage during normal operation
Fig. 5 PV voltage, PV current and DC-link voltage tracking

Case 2: Balanced Source with Voltage Sag
 The simulation in case-2 is conducted
considering balanced voltage sag with and
without PV-UPQC.
 The occurrence of a 3-phase fault results in 30%
of sag and the voltage decreases from its
nominal value between the period 0.1s and 0.2s
in all phases illustrated in Figures 6 to 8.
 The output load voltage is kept constant (325V)
by using PV-UPQC. Fig 6 depicts the load voltage
sag compensation.
 For the time 0.1 to 0.2 sec, there is a sag in the
source voltage which is mitigated by PV-UPQC.
 Fig 7 depicts the source current with a sag of
30% for 0.1 to 0.2 sec and the compensated load
current is shown in Fig 8.
Fig. 6 Source Voltage with Sag and Load voltage sag
compensation
Fig. 7 Source current with sag Fig. 8 Load current with PV-UPQC

Case 3: Unbalanced Supply Voltage
 In case 3, the single-phase voltage sag is
evaluated with and without PV-UPQC.
 The occurrence of a single-phase fault results in
30% of sag and the voltage decreases from its
nominal value.
 Sag event occurs only in phase A. Consequently, as
other phases are not affected, both phases B and
C keep their nominal value, as shown in Figures 9
to 11.
 The output load voltage is kept constant (325V)
with PV-UPQC.
 Fig 9 depicts the single-phase load voltage sag
compensation. For the time 0.1 to 0.2 sec, there is
a sag in phase A of source voltage which is
mitigated by PV-UPQC.
 Fig 10 depicts the source current with the sag of
30% in phase A for 0.1 to 0.2 sec and the
compensated load current is shown in Fig 11.
Fig. 9 Single-phase source voltage with sag and Load voltage sag compensation
Fig. 10 Single-phase source current with sag Fig. 11 Load current with PV-UPQC

Case 4: Balanced Voltage Swells
 In case 4, the simulation is conducted considering
balanced voltage swell with and without PV-UPQC.
 The occurrence of a 3-phase fault results in a 30%
swell and the voltage increases from its nominal
value between the period 0.1s and 0.2s in all the
phases.
 The simulation is illustrated in figures 12 to 14.
 The output load voltage is kept constant.
 Fig 12 depicts the balanced load voltage swell
compensation.
 For the time 0.1 to 0.2 sec, there is a balanced
swell in the source voltage which is mitigated by
PV-UPQC.
 Fig 13 depicts the balanced source current with
swell for 0.1 to 0.2 sec and the compensated load
current is shown in Fig 14.
Fig. 12 Source voltage with swell and Load voltages with PV-UPQC
Fig. 13 Source current with swell Fig. 14 Load current with PV-UPQC

FFT Analysis of Current and Voltage
 Fig 15 and Fig 16 shows the fast Fourier
transform (FFT) analysis of the source
current and Load current respectively.
 In the case of non-linear load, the load
current has a THD of 19% while the source
current THD is reduced to 4.9% which is
within the range of acceptable limits.
 Fig 17 shows the FFT analysis of source
voltage.
 We can see the large spikes at 250 Hz (5th
harmonic) and 350 Hz (7th harmonic). The
THD of the wave is 33%.
 Fig 18 shows the compensated load
voltage FFT analysis. Its THD is reduced to
2%.
Fig. 15 FFT analysis of Source Current Fig. 16 FFT analysis of Load Current
Fig. 17 FFT analysis of Source Voltage Fig. 18 FFT analysis of Load Voltage

Conclusion
 This work has introduced a PV UPQC system for the control of unwanted disturbances in the
grid side as well as for harmonic compensation.
 The active PV power is fed to the grid through combined series-shunt APFs.
 Especially the series APF shares reactive power under nominal loading that reduces the burden
on shunt APF.
 To achieve the desired objectives in a grid-ties system detailed analysis with control of
individual APFs has been delineated.
 Under a sudden change in supply (sag-swell) and load side (linear-non-linear), results show
effective workability of the system with a significant reduction in grid current THD.
 The proposed system can act as a suitable alternative for power quality improvement while
processing clean energy generation.

REFERENCES
 P. K. Sorte, K. P. Panda and G. Panda, "Current Reference Control Based MPPT and Investigation
of Power Management Algorithm for Grid-Tied Solar PV-Battery System," IEEE Systems Journal,
vol. 16, no. 1, pp. 386-396, March 2022.
 IEEE Std. 519TM-2014.IEEE Recommended Practice and Requirements for Harmonic Control in
Electric Power Systems, IEEE Power and Energy society.
 H. Akagi, Y. Kanazawa, A. Nabae, “Generalized Theory of the Instantaneous Reactive Power in 3-
Phase Circuits”, in Proc. IPEC-Tokyo’83 Int. Conf. Power Electronics, Tokyo, pp. 1375-1386.
 H. Akagi, Y. Kanazawa, and A. Nabae, “Instantaneous Reactive Power Compensators Comprising
Switching Devices without Energy Storage Components,” in IEEE Transactions on Industry
Applications, vol. IA-20, no. 3, pp. 625-630, May 1984.
 E. H. Watanabe, R. M. Stephen, and M. Arcdes, “New concept of instantaneous active and
reactive powers in electric systems with generic load,” IEEE Trans. on power delivery, vol.8, April
1993, pp. 697-703.

Thank You

Operation of UPQC with PV for Power Quality

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