Shunt Active Power Filter for Power Quality Improvement of

Renewable Energy Systems: A Case Study

FOUAD ZARO

Electrical Engineering Department,

Palestine Polytechnic University,

Hebron City,

PALESTINE

dynamic response to regulate the grid's power factor (PF).

Key-Words: - Shunt active power filter, Harmonics mitigation, Power factor correction, Distributed generation,

Hysteresis current controller, Power quality improvement

Received: September 17, 2022. Revised: September 10, 2023. Accepted: Ocotber 12, 2023. Published: November 16, 2023.

1 Introduction

The connection of utility grids with new renewable

loads, variable frequency drives, and soft starters are

the major cause of poor PQ problems like

harmonics, poor power factor, sag, and swell

distortions, [1], [2], [3]. Therefore, it’s critical to

evaluate new solutions to increase the quality of

utility services.

solutions to mitigate PQ problems, passive power

filters (PPF) have many drawbacks, such as their

inability to compensate for sub-harmonics, tuning

harmonics and increasing the power factor up to

unity. Recently, APFs have become the most

effective solution to eliminate the harmonics, inter-

harmonics, and sub-harmonics due to their

advantages; (i) fast response to grid variations, (ii)

ability to compensate for random harmonics. (iii)

generating negative voltage harmonics to cancel the

Fig. 1: Series active power filter configuration, [7].

filter connected in parallel with nonlinear loads that

are used to reduce the grid’s current distortion and

increase the utility power factor by injecting

negative current harmonic into the grid. Figure 2

shows the topology of shunt APF.

using VSI is more efficient than CSI in high-power

applications (in MV applications), while CSI is

better than VSI in low-power applications. CSI

needs additional overvoltage protection in the DC-

link inductor in case of switch faults. Both types

have significant losses, the main losses in VSI are in

its AC-linking inductance filter while the losses in

CSI are in its DC-link inductance, [8]. Since the

total harmonic distortion of the current (THDi) in

Shunt-APF is connected to an 11 kV, 50 Hz grid, to

compensate and mitigate the effect of non-linear

load that represents the topology of industrial zone

loads. Figure 6 shows the overall system design.

Fig. 6: Overall system design.

practical harmonic measurements for the first ten

harmonic content. Figure 7 shows the load current

wave shape.

Two-phase calculation is done depending on the

Clark transform matrix in equation (1), followed by

instantaneous real and reactive power calculation

according to equation (2). Figure 8 shows a two-

phase calculation block diagram. Figure 9 shows the

Fig. 10: The block diagram of evaluating P-ac.

Fig. 11: Real power separation, (a) total power, (b)

P-dc component, and (c) P-ac component.

evaluating reference currents in a two-phase model

according to equation (3) followed by inverse Clark

transform according to equation (4) to get the

references in the three-phase model. Figure 12

shows reference current curves in two-phase and

three-phase models respectively.

Fig. 12: Reference current in two-phase and three-

phase models, respectively.

Hysteresis Controllers make the grid current

STATCOM. Table 2 summarizes a comparison of

Table 2. Comparison of APF performance