Performance enhancement of a grid-connected solid-oxide fuel cell using an improved control scheme Preeti Gupta ⇑ , Vivek Pahwa, Y.P. Verma UIET, Panjab University, Chandigarh, India article info Article history: Received 26 March 2020 Received in revised form 9 May 2020 Accepted 22 May 2020 Available online 17 June 2020 Keywords: SOFC Utilization factor Air excess ratio Fuel controller Physical dynamic behavior Durability abstract Among fuel cells, solid oxide fuel cell (SOFC) is great for power generation due to its efficiency and flex- ibility. However, it experiences a challenge due to its slow dynamic response during varying load, that its material has low durability. Thus to enhance its dynamic behavior in order to improve its life an essential requirement is to maintain proper physical and chemical stress on it. In this work, a single-input double- output fuel control scheme for the grid connected double-input single-output SOFC based system is developed and implemented in MATLAB/SIMULINK environment. This scheme utilizes a proportional and integral (PI)-based controller to maintain the fuel utilization factor within limits by thrusting the optimized fuel inputs (hydrogen and oxygen) to the SOFC. It performs under varying load without affect- ing the operational feasibility and power-tracking capability of the fuel cell. As a result, the electrical out- put characteristics enhance for longer period of operation and SOFC’s life expectancy increases for normal and quadruple degradation rates. Comparison of simulation results of proposed controlled operation in time-domain shows superiority in its physical dynamic performance in contrast to uncontrolled operation. Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Confer- ence on Aspects of Materials Science and Engineering. 1. Introduction Among various types of renewable sources of energy, fuel cell is an attractive option due to high efficiency and myriads of applica- tions [1,2]. The fuel cells are the latest technologies available to convert chemical energy to electrical energy, irrespective of the system size and loading factor [3]. Various types of fuel cells like alkaline fuel cell (AFC), polymer exchange membrane fuel cell (PEMFC), microbial fuel cell (MFC), solid oxide fuel cell (SOFC), etc are available [4,5]. Among these, SOFC based power system is coming up very fast in the field of electrical power generation in contrast to other fuel cell based power systems due to its advan- tages like reliability, less emissions, flexibility in fuel consumption are silent [6–9]. Yet it has a scope of a large research due to its slow dynamic response and durability issues. Over the time, it has accordingly being explored on designing the layout/structure [10], material stress [11], physical modeling [12,13], control-oriented modeling [14] and various control tech- niques [15,16] to improve the physical behavior of the SOFC. The control of various operating parameters such as stack voltage and current, fuel intake, partial pressures of hydrogen and oxygen, air excess ratio, fuel utilization factor and operating temperature of SOFC [17–23] which are associated with this multiple-input multiple-output (MIMO) fuel cell. All of these operating parame- ters play an important role in control of SOFC. Especially the stack voltage, current, power and fuel utilization factor should remain in their limits for satisfactory operation of fuel cell as, these define the feasible operational area (FOA) for SOFC. Since the literature dic- tates that the fuel, hydrogen must be utilized within its safe oper- ating limits, i.e. 0.7U f  0.9 because its fuel utilization factor is its safety factor [17,19,20]. The over usage of it occurs duringU f  0.9 whereas, it gets underused duringU f  0.7 and both these condi- tions are risky operations of the SOFC [22]. Although, the work in [17] maintains the fuel utilization factor within its limits but it is achieved at the cost of its output power tracking capability while performing a single-input single-output (SISO) control scheme. Moreover, it does not discusses another vital operating parameter, air which works as a coolant. Its importance has been scrutinized for long-term operation through designing of electrodes to https://doi.org/10.1016/j.matpr.2020.05.575 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Aspects of Materials Science and Engineering. ⇑ Corresponding author. E-mail address: er.guptapreeti07@gmail.com (P. Gupta). Materials Today: Proceedings 28 (2020) 1990–1995 Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr