To maximize conversion efficiency, photovoltaic (PV) systems generally operate in the maximum power point tracking (MPPT) mode. However, due to the increasing penetration level of PV systems, there is a need for more developed control functions in terms of frequency support services and voltage control to maintain the reliability and stability of the power grid. Therefore, flexible active power control is a mandatory task for grid-connected PV systems to meet part of the grid requirements. Hence, a significant number of flexible power point tracking (FPPT) algorithms have been introduced in the existing literature. The purpose of such algorithms is to realize a cost-effective method to provide grid support functionalities while minimizing the reliance on energy storage systems. This paper provides a comprehensive overview of grid support functionalities that can be obtained with the FPPT control of PV systems such as frequency support and volt-var control. Each of these grid support functionalities necessitates PV systems to operate under one of the three control strategies, which can be provided with FPPT algorithms. The three control strategies are classified as: ① constant power generation control (CPGC), ② power reserve control (PRC), and ③ power ramp rate control (PRRC). A detailed discussion on available FPPT algorithms for each control strategy is also provided. This paper can serve as a comprehensive review of the state-of-the-art FPPT algorithms that can equip PV systems with various grid support functionalities.

中文翻译：

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电网支持光伏系统中最先进的灵活功率点跟踪算法综述：分类与应用

为了最大限度地提高转换效率，光伏 (PV) 系统通常在最大功率点跟踪 (MPPT) 模式下运行。然而，由于光伏系统的普及程度不断提高，在频率支持服务和电压控制方面需要更发达的控制功能，以维持电网的可靠性和稳定性。因此，灵活的有功功率控制是并网光伏系统满足部分电网要求的强制性任务。因此，现有文献中引入了大量灵活的功率点跟踪（FPPT）算法。此类算法的目的是实现一种经济高效的方法来提供电网支持功能，同时最大限度地减少对储能系统的依赖。本文全面概述了可通过光伏系统的 FPPT 控制获得的电网支持功能，例如频率支持和伏特无功控制。这些电网支持功能中的每一个都需要光伏系统在三种控制策略之一下运行，这些控制策略可以通过 FPPT 算法提供。三种控制策略分为：①恒定发电控制（CPGC），②功率储备控制（PRC），③功率斜坡率控制（PRRC）。还详细讨论了每种控制策略的可用 FPPT 算法。本文可以作为对最先进的 FPPT 算法的全面回顾，这些算法可以为光伏系统配备各种电网支持功能。