Contents lists available at ScienceDirect Solar Energy journal homepage: www.elsevier.com/locate/solener Enhanced performance of PV power control using model predictive control Fernand Diaz Franco ⁎ , Tuyen V. Vu, David Gonsulin, Hesan Vahedi, Chris S. Edrington Center for Advanced Power Systems, Florida State University, United States ARTICLE INFO Keywords: PV system MPPT MPC CHIL ABSTRACT This paper focuses on the use of model predictive control (MPC) to control a DC/DC boost converter in order to regulate the PV power. When integrated with the grid, the PV system must deliver maximum power most of the time; however, if a voltage sag occurs, new grid codes demand that the control system should limit the PV power generated to avoid over current conditions and, consequently, a grid disconnection. Maximum and reduced power modes are implemented following the MPC strategy to achieve high–performance and stable operation in the system. First, the system is modeled in Matlab/Simulink and PLECS to understand its operation and to evaluate the effectiveness of the proposed algorithm. Secondly, experimental results are verified using the control hardware–in–the–loop (CHIL) approach on the Real Time Digital Simulator (RTDS). 1. Introduction During normal conditions, the maximum power point tracking (MPPT) technique are required on PV installations to maximize solar harvesting and increase the profit provided by feed-in tariff govern- mental programs. Different methods for MPP tracking on PV systems have been proposed in the literature and can be classified into direct and indirect methods. Indirect methods require prior knowledge of the PV array characteristics under different irradiance/temperature condi- tions. In contrast, direct methods use voltage and current measurements from the PV array to achieve the optimal operation point. The selection of a specific technique depends mostly on the implementation com- plexity, number of sensors required, and convergence speed that is re- quired for a certain application like solar vehicles (Ko and Chao, 2012). In the literature, the Hill Climbing/Perturb and Observe (P & O) (Balasankar et al., 2017; Rezk and Eltamaly, 2015) and Incremental Conductance (López et al., 2016) techniques are the most widely used because they are easy to implement, and they provide good efficiency that goes from 96 to 99% (Ezinwanne et al., 2017; Bendib et al., 2015). Due to the increase penetration of PV systems into the grid, current grid codes demand ancillary services to improve overall power system reliability (Nanou and Papathanassiou, 2014). This is the case when a fault occurs, the PV system must deliver voltage support by injecting reactive power at the point of connection (Yang et al., 2014; Hudson and Heilscher, 2012). In this scenario the system should operate in a reduced power mode (RPM) to decrease the active power injection, and in this way, avoid over current condition and eventual disconnection of the PV plant. Therefore, in a RPM, the PV controller must select a lower power operating point than the MPP to lessen the negative impact of grid overloading. Therefore, PV controllers must offer a fast and reliable transition between the normal and fault operation mode to satisfy current standards. Pulse width modulation (PWM) techniques are commonly used to achieve the operation modes previously described. The proper selection of the switching frequency is an important step in the system design because it can affect both the size of the converter—by increasing the size of the energy store elements like inductances—as well as the overall efficiency of the system (Rodriguez-Rodrıguez et al., 2017). Moreover, the classical control techniques with PI regulators assume that the converter is a linear system, and the transient performance as well as the robustness of the system are limited by the selection of the compensator bandwidth (Rivera et al., 2013). Several articles have been published in literature in order to obtain a RPM from PV arrays. They are implemented for both single- and two- stage PV systems (Kiran et al., 2015; Urtasun et al., 2013; Sangwongwanich et al., 2016). All utilize a P & O-based approach technique to move PV power P PV operation from MPP to a lower point. This is done by means of a perturbation step change on the PWM duty cycle. The drawbacks on this method are the oscillations around the new PV operation point and the speed of the process. Although, similar P & O modified methods used for MPPT could be implemented to reduce the mentioned disadvantages (Dileep and Singh, 2015; Harrag and Messalti, 2015; Sheik Mohammed et al., 2016), the tracking speed re- mains as the major weakness for a fast controller response during transient events like grid faults. Model predictive control (MPC) offers an alternative to overcome http://dx.doi.org/10.1016/j.solener.2017.10.005 Received 8 May 2017; Received in revised form 14 September 2017; Accepted 2 October 2017 ⁎ Corresponding author. E-mail address: fd13c@my.fsu.edu (F. Diaz Franco). Solar Energy 158 (2017) 679–686 0038-092X/ © 2017 Elsevier Ltd. All rights reserved. MARK