**1. Introduction**

In the present age of computerization and digitalization, complex devices with fast processing controllers draw current shapes that are unwanted in the supply system. This significantly degrades the quality of the power (i.e., voltage and current) supplied or available for other loads [1–5]. A specific conditioning equipment known as a unified power quality conditioner (UPQC) can be employed for such types of loads to resolve both voltage- and current-related issues, thus assisting with the efficient operation of the load and preventing the supply lines from being infected with the non-linearities and reactive power demand of the load [6–21].

Various UPQC control methods considering different compensating scenarios have been considered by the research community. Along with regular voltage and current compensation, reactive power compensation by a device has also proven to be a major utilization [11]. The ability of reactive power compensation has been explored further in order to be shared among the shunt and series APFs of the device by using the power angle control (PAC) concept [11–14,18,20]. It has been effectively implemented in a three-phase three-wire system [11,12] and a three-phase four-wire system [14,20]. The PAC concept has also been implemented in a single-phase system-based UPQC, as discussed in [18].

**Citation:** Patnaik, N.; Pandey, R.; Satish, R.; Surakasi, B.; Abdelaziz, A.Y.; El-Shahat, A. Single-Phase Universal Power Compensator with an Equal VAR Sharing Approach. *Energies* **2022**, *15*, 3769. https:// doi.org/10.3390/en15103769

Academic Editor: Byoung Kuk Lee

Received: 1 April 2022 Accepted: 19 May 2022 Published: 20 May 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

The estimation of the PA (power angle), as discussed in the literature, is based on the PQ concept, primarily for three-phase systems utilizing power components to calculate the PA. It has already been well-established that, under non-sinusoidal supply voltage conditions, PQ concept-based harmonic compensation exhibits a poor performance compared with the SRF concept [22]. Thus, under similar conditions, a PA estimation with a PQ concept also followed a similar trail, as discussed in the manuscript. It also necessitated the regular computation of VAR sharing by each APF for the computation of the PA [11]. This regular VAR computation can be avoided by using two APFs with an equal rating, thus sharing equal reactive power. The estimation of the PA (power angle), as discussed in the literature, is based on the PQ concept, primarily for three‐phase systems utilizing power components to calculate the PA. It has already been well‐established that, under non‐sinusoidal supply voltage conditions, PQ concept‐based harmonic compensation exhibits a poor performance compared with the SRF concept [22]. Thus, under similar conditions, a PA estimation with a PQ concept also followed a similar trail, as discussed in the manuscript. It also necessitated the regular computation of VAR sharing by each APF for the computation of the PA [11]. This regular VAR computation can be avoided by using two APFs with an equal rating, thus sharing equal reactive power. In this paper, we present a comprehensive compensating device, termed a UPC

angle control (PAC) concept [11–14,18,20]. It has been effectively implemented in a three‐phase three‐wire system [11,12] and a three‐phase four‐wire system [14,20]. The PAC concept has also been implemented in a single‐phase system‐based UPQC, as dis‐

*Energies* **2022**, *15*, x FOR PEER REVIEW 2 of 19

cussed in [18].

In this paper, we present a comprehensive compensating device, termed a UPC (universal power compensator), for a single-phase system with equal APF ratings whose control action exhibits a few important features. One is the realization of equal reactive power sharing between both APFs, thus avoiding a regular VAR computation. Secondly, the equal VAR sharing is comprehended by the PA estimation without power estimations, directly utilizing the SRF current parameters (id-iq), which are estimated for current harmonic compensation. Thirdly, as only the d-q current parameters are used for the PA estimation, it remains unfazed due to the non-sinusoidal supply voltage condition. To demonstrate its effectiveness, a comparative analysis is presented in reference to PQ concept-based compensation and the PA estimation under a non-sinusoidal supply voltage condition. (universal power compensator), for a single‐phase system with equal APF ratings whose control action exhibits a few important features. One is the realization of equal reactive power sharing between both APFs, thus avoiding a regular VAR computation. Secondly, the equal VAR sharing is comprehended by the PA estimation without power estima‐ tions, directly utilizing the SRF current parameters (id‐iq), which are estimated for current harmonic compensation. Thirdly, as only the d‐q current parameters are used for the PA estimation, it remains unfazed due to the non‐sinusoidal supply voltage condition. To demonstrate its effectiveness, a comparative analysis is presented in reference to PQ concept‐based compensation and the PA estimation under a non‐sinusoidal supply voltage condition.

A single-phase UPC with a shunt and series APF combined through a DC-link capacitor is shown in Figure 1. The specific load is considered to be an arrangement of the linear and non-linear load. The non-linear load comprises a single-phase diode bridge rectifier with an RL load on the DC side whereas the linear load consists of only a series combination of the active and reactive load. With both loads in operation, the source current harmonics are not as high, but they have a considerable VAR demand that needs to be compensated for on an equal sharing basis by the APFs of the UPC. When the non-linear load acts alone, it contaminates the source current with the harmonics to a greater extent, which is tackled by the shunt APF. Voltage sag, voltage swell and voltage harmonics, or the supply side disturbances, should be mitigated by the series APF. A single‐phase UPC with a shunt and series APF combined through a DC‐link ca‐ pacitor is shown in Figure 1. The specific load is considered to be an arrangement of the linear and non‐linear load. The non‐linear load comprises a single‐phase diode bridge rectifier with an RL load on the DC side whereas the linear load consists of only a series combination of the active and reactive load. With both loads in operation, the source current harmonics are not as high, but they have a considerable VAR demand that needs to be compensated for on an equal sharing basis by the APFs of the UPC. When the non‐linear load acts alone, it contaminates the source current with the harmonics to a greater extent, which is tackled by the shunt APF. Voltage sag, voltage swell and voltage harmonics, or the supply side disturbances, should be mitigated by the series APF.

**Figure Figure 1. 1.** Single Single-phase UPC system with equal reactive power sharing approach. ‐phase UPC system with equal reactive power sharing approach.
