Mathematical Problems in Engineering
Volume 2022 (2022), Article ID 6389132, 43 pages
https://doi.org/10.1155/2022/6389132
A Review of Control Techniques and Energy Storage for Inverter-Based Dynamic Voltage Restorer in Grid-Integrated Renewable Sources
School of Electrical Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India
Correspondence should be addressed to C. Dhanamjayulu
Received 19 August 2022; Accepted 12 September 2022; Published 29 September 2022
Academic Editor: Albert Alexander Stonier
Copyright © 2022 Devalraju Prasad and C. Dhanamjayulu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Power quality (PQ) is a key issue, particularly for technologically advanced process equipment, whose performance mainly depends on the quality of supply. Problems with PQ such as voltage swells/sags, interruptions, and harmonics are defined by any voltage, current, or frequency abnormalities causing damage or failure of the end-user equipment. Outages and interruptions lead to malfunctioning of end-user equipment or sensitive loads, such as diagnostic equipment in healthcare facilities, clinics, educational institutions, and detention centers, while further increasing significant economic losses. Custom power devices (CPDs) are recommended for enhancing power quality, and the best and most economical solution is considered to be the dynamic voltage restorer (DVR). Several methods are suggested to improve the PQ by using the dynamic voltage restorer; among them, most encouraging ways are to use a multilevel inverter (MLI) in the dynamic voltage restorer. This article combines the latest work of the literature, as well as a detailed discussion on PQ issues of the grid-integrated renewable energy sources (RESs), DVR principle with its operating procedures, system components, energy storage-based DVR topologies, DVR control unit, and DVR power converter-based topologies. In addition, synthesis of energy storage, control strategies, and multilevel inverters for DVR. This review benefits those interested in investigating DVR as a relevant and comprehensive reference.
1. Introduction
In the smart era, microprocessor-controlled devices or digital, electronic, and nonlinear devices are extensively used in all sectors of the industry. Nearly all these devices are sensitive, have electrical supply disruptions at any minute, and cannot be operated properly. In addition, several supplies have also been increased, which degrades power quality (PQ). Problems that happen because of inadequate power quality are data errors, automatic resets, memory losses, UPS alarms, equipment failures, software corruptions, circuit board failures, power supply problems, and overheating of electrical distribution systems. Considering these realities, PQ has become progressively critical. Not only PQ issues but also the issues related to voltage are also most important from sensitive nonlinear loads and end-users [1, 2].
The use of sensitive loads such as diagnostic equipment in health centers, educational institutions, and detention centers over several years has been fourfold, which leads to a concern with the quality of power of sensitive loads [3]. If power quality is insufficient, serious economic losses, losses in manufacturing, outage of sensitive and critical loads, and lack of information could have serious consequences [4]. Consequently, high power quality is essential for utilities, customers, and producers of electrical appliances too. The essential power quality issues include voltage swells, sags, harmonics, transients, flickers, fluctuations, and interruptions [5]. These are discussed in the next section. The sensitive and critical loads must prevent these issues in terms of power quality and voltage disturbances. In this regard, a wide range of solutions has been introduced including the best and most efficient solution for the compensation and mitigation of voltage disturbance known as custom power devices (CPDs) [6]. They act as compensating devices, each with its own control and application. CPDs such as a parallel-connected distribution static synchronous compensator (DSTATCOM), are used for correcting the power factor; for voltage compensation, the dynamic voltage restorer (DVR) is used and is connected in series; a parallel-series connected unified power quality conditioner (UPQC) can simultaneously inject voltage in series and current in parallel; however, UPQC and DSTATCOM are larger and more expensive, rather than DVR [7]. In modern power systems, the most serious and usual power quality issues are voltage sags, and DVR is used as the least expensive voltage sag solution [8].
When a voltage disturbance occurs on the supply side, the DVR supplies the required voltage to the load side. The DVR also protects from supply-side disturbances to sensitive and critical loads [9, 10]. This means that the DVR is important to compensate for voltage sags and to protect the sensitive load. The DVR is the best CPD since it has low costs, has small sizes, and can respond quickly to voltage disturbances. As an example, the DVR installation cost for the 2–10 MVA power supply is USD 300/kVA, while uninterruptible power supplies (UPSs) installation costs are USD 500/kVA. The servicing and operating costs of DVR are approximately 5% of its capital investment; however, it is much higher (about 15%) [1]. UPQC is a DSTATCOM-DVR combination with two power converters; hence, the structure of the DVR is, therefore, less than UPQC. DVR and DSTATCOM are closely related; however, DVR is used to protect the sensitive loads from supply interruptions, whereas DSTATCOM is used to protect critical loads from load-side disturbances. Furthermore, the DVR quickly (less than 1/4 cycle) responds to voltage disturbances, unlike other CPDs, such as the static VAR compensator (SVC) (2-3 cycle) [11].
Many topologies of DVR from different points of view of energy storages, power converters, and control systems have been investigated to improve power quality, cut costs, and improve the performance of DVR [12]. Furthermore, it has become widely attractive to modify DVR topology and integrate renewable energy resources with the DVR. Some general reviews on DVRs were carried out that a detailed study is lacking on modified DVR configurations and integration with renewable energy [13, 14]. Significant research is being conducted on DVR innovation and is now advanced but not many of the survey papers in the published literature are accessible. Remya et al. reviewed the DVR and reported on the challenges of the DVR systems [15]. Farhadi-Kangarlu et al. reported the combined overall DVR topologies, compensation techniques, and control strategies [16]. Significant research development in DVR technology for fifteen years after the first installation of DVR was published by El-Gammal et al. [17]. This paper intends to give a comprehensive evaluation of different components of DVR structure, as well as the integration of distributed generations into multi-inverter-based DVR. This article provides a significant contribution in the following ways:(i)Discussion of the power quality difficulties associated with RES integration into the grid(ii)To understand the working principles of DVR, the basic components, alternative DVR topologies from an energy storage approach, DVR control units, and DVR compensation techniques are provided(iii)Discussion and extensive study of different grid-connected multilevel inverters, as well as multilevel inverter-based DVR integration with distributed generation, for optimizing voltage profile
Engineers and researchers working on the issues of power quality and the mitigation of voltage disturbances will be able to use them on an extensive basis.
The remainder of the article is organized accordingly. Section 2 describes the power quality problems of RES connected to the grid, grid-integrated RES requirements, PQ standards, classifications, causes, and effects. The most important custom power device and applications have also been clarified. In Section 3, the principle of DVR and its various operating modes, DVR circuit components, and DVR topologies are presented from the point of view of energy storage. Following this, Section 4 reviews DVR control units and compensating techniques. The analysis of various grid-tied multilevel inverters with their advantages and disadvantages along with their performance indices and, finally, an elaborated review on multilevel inverter-based DVRs are provided in Section 5; the conclusions and scope of future work are given in Section 6.
2. Power Quality Issues in Grid-Connected Renewable Energy Sources
There is considerable global attention to the utilization of renewable energy sources (RESs) for electricity generation. This is because of the negative environmental effects of fossil fuels being burned to convert energy, which emits an enormous amount of CO2 and other greenhouse gases into the air. Figure 1 depicts a few of the renewable energy sources.