Please cite this article in press as: D. Fernandes, et al., State feedback control for DC-photovoltaic systems, Electr. Power Syst. Res. (2016), http://dx.doi.org/10.1016/j.epsr.2016.08.037 ARTICLE IN PRESS G Model EPSR-4833; No. of Pages 8 Electric Power Systems Research xxx (2016) xxx–xxx Contents lists available at ScienceDirect Electric Power Systems Research j o ur na l ho mepage: www.elsevier.com/locate/epsr State feedback control for DC-photovoltaic systems Darlan Fernandes a , Rogerio Almeida a , Tatiana Guedes a , A.J. Sguarezi Filho b,∗ , F.F. Costa c a Universidade Federal da Paraíba – UFPB, João Pessoa, Brazil b Universidade Federal do ABC – UFABC, Santo André, Brazil c Universidade Federal da Bahia – UFBA, Salvador, Brazil a r t i c l e i n f o Article history: Received 25 April 2016 Received in revised form 28 August 2016 Accepted 31 August 2016 Available online xxx Keywords: Photovoltaic DC–DC converter Feedback control State-space Average state Ackermann control strategy a b s t r a c t This paper proposes an alternative state feedback-based control strategy to a DC–DC converter applied to regulation purposes in photovoltaic (PV) systems. The PV generation voltage output level is determined through a maximum power point tracking (MPPT) algorithm. Moreover, the proposed control technique also provides a suitable duty-cycle for the switching of the DC–DC converter to improve its dynamics with regards the reference voltage generation, provided by the MPPT algorithm. The control technique relies on a state-space equations description of the PV generator connected to the converter. The controller gains are designed by building a proper characteristic polynomial which takes into account the conditions for system controllability using Ackermann formulation. Moreover in order to experimentally verify the converter system control dynamics, a switched load has been applied and controlled to set constant the converter output voltage. This control for this load secure it a mean value of resistance through a PWM period during the experiment. The proposed method is tested by means of computational simulations in Matlab/Simulink environment. In addition, an experimental apparatus has been mounted to emulate the simulated results and to corroborate the technique efficacy. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Up to 2010, the contribution of PV systems for the energy matrix of the world was relatively not meaningful. However, from the beginning of the present decade, one observes growing rates of use of such sources both grid-connected systems and isolated systems as rural installations where connection is economically prohibitive, mainly for developing countries [1–6]. It is estimated that in 2035, the energy provided from photovoltaic systems will increase by more than 20 times, expanding to 846 TWh [7]. A paramount issue associated not only to PV systems but to any renewable source, is the efficiency of the conversion of the energy extracted from the source and delivered to the load or to be injected into the grid. To this end, a critical action is develop- ing methods to assure that the maximum power is being drawn from the PV cells. This is carried out by the MPPT algorithms in ∗ Corresponding author at: Av. dos Estados, 5001, Santo André CEP 09210-580, Brazil. E-mail addresses: darlan@cear.ufpb.br (D. Fernandes), rogerio@cear.ufpb.br (R. Almeida), tpguedes@yahoo.com.br (T. Guedes), alfeu.sguarezi@ufabc.edu.br (A.J. Sguarezi Filho), fabiano.costa@ufba.br (F.F. Costa). conjunction with the DC–DC regulation stage or together with the inverter control [8,9]. The output voltage of a PV cell is governed by its I–V curve. It bears a random nature due to the irregular solar irradiation and environmental temperature variations. To allow the energy be properly drained from it, the output voltage must be regulated. This task can be performed by means of set of batteries or through DC–DC converters, which reduce costs with maintenance and replacement of the batteries. There are also strategies combining batteries with DC–DC converters that are used to charge them [10]. Nevertheless, the batteries maintenance is still a matter to be taken into account and, therefore, voltage regulation procedures using only DC–DC converters tend to be economically advantageous over other approaches. The regulated voltage can then be converted to AC voltage to supply an isolated voltage, or to inject power into the grid. Applications such as hybrid grids [11–13], charge bat- teries and water pumping appliances demand efficient DC voltage regulation. This can be accomplished with the aid of MPPT algo- rithms which can use the I–V curve characteristics to determine an operating point so as to assure that the maximum possible power is being extracted from the PV generator [14–16]. This operation point is set by the DC–DC converter which establishes an optimal power flux under a constant voltage across its output terminals. The http://dx.doi.org/10.1016/j.epsr.2016.08.037 0378-7796/© 2016 Elsevier B.V. All rights reserved.