Citation: Gholami, K.; Behi, B.; Arefi, A.; Jennings, P. Grid-Forming Virtual Power Plants: Concepts, Technologies and Advantages. Energies 2022, 15, 9049. https:// doi.org/10.3390/en15239049 Academic Editors: Zhengmao Li, Tianyang Zhao, Ke Peng, Jinyu Wang, Zao Tang and Sumedha Sharma Received: 26 October 2022 Accepted: 25 November 2022 Published: 29 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. 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/). energies Review Grid-Forming Virtual Power Plants: Concepts, Technologies and Advantages Khalil Gholami 1 , Behnaz Behi 2 , Ali Arefi 2 and Philip Jennings 2, * 1 Department of Electrical Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah 67146, Iran 2 Discipline of Engineering and Energy, Murdoch University, Murdoch, WA 6150, Australia * Correspondence: p.jennings@murdoch.edu.au Abstract: Virtual Power Plants (VPPs) are efficient structures for attracting private investment, increasing the penetration of renewable energy and reducing the cost of electricity for consumers. It is expected that the number of VPPs will increase rapidly as their financial return is attractive to investors. VPPs will provide added value to consumers, to power systems and to electricity markets by contributing to different services such as the energy and load-following services. One of the capabilities that will become critical in the near future, when large power plants are retired, is grid-forming capability. This review paper introduces the concept of grid-forming VPPs along with their corresponding technologies and their advantages for the new generation of power systems with many connected VPPs. Keywords: virtual power plant; grid-forming inverters; renewable energy; energy storage; review 1. Introduction Global warming has reached a point where it is causing serious climate change, and this has focused the world’s attention on reducing the use of fossil fuel-based sources to generate electrical power [1]. In addition to this, fossil fuels are being seriously depleted, and some believe that they should be preserved for high-value applications and future generations. As a result, the use of renewable energy sources (RESs) such as solar and wind has experienced a sharp increase in recent years. Initially, large-scale RESs were integrated into distribution networks by utilities with different objectives [2,3]. For example, the authors of [4] advocated RESs to enhance the power quality of distribution networks. Likewise, reliability enhancement was another application of the integration of RESs into the power distribution grid [5]. From this, it is clear that RESs not only decrease the considerable amount of pollution derived from power generation, but also bring advantages such as loss minimization and reliability improvement. Similarly, consumers have attempted to reduce their electricity costs and cut their CO 2 emissions by installing photovoltaic (PV) panels on their house roofs [6]. Although this mechanism often helps to decrease their electricity bills, there remain some unresolved issues. Firstly, their additional generation may be partially wasted because they cannot participate effectively in the wholesale electricity market, because their generation is not significant enough to allow them to have an active role in the market. Another problem of such standalone systems is that they experience more power outages due to natural disasters, like hurricanes, earthquakes and storms. In order to tackle these problems related to rooftop PV, the concept of a virtual power plant (VPP) has been introduced [7]. Generally speaking, VPP means combining dispersed small-scale generators to create a unified system, resulting in increasing their ability to participate in the wholesale electricity market as well as increasing the stability of the grid. VPPs can be easily formed based on existing systems and they can decrease public expenditure on additional transmission lines. Energies 2022, 15, 9049. https://doi.org/10.3390/en15239049 https://www.mdpi.com/journal/energies