Small signal stability analysis of dish-Stirling solar thermal based autonomous hybrid energy system Dulal Ch. Das ⇑ , N. Sinha, A.K. Roy Electrical Engineering Department, NIT Silchar, Assam, India article info Article history: Received 10 July 2013 Received in revised form 1 June 2014 Accepted 3 June 2014 Keywords: Dish-Stirling solar thermal systems (DSTS) Genetic algorithm Aqua electrolyzer Fuel cell Diesel engine generator abstract Present work presents small signal stability analysis of an autonomous hybrid energy system with dish- Stirling solar thermal systems (DSTS) in integration with diesel engine generators (DEG), fuel cells (FC), battery energy storage system (BESS), and aqua electrolyzer (AE). The performance of Genetic algorithm (GA) optimized integral (I), proportional plus integral (PI), and proportional-integral-derivative (PID) con- trollers in containing the frequency deviation in the proposed system has been investigated. The dynamic performance of all three controllers, so optimized, is compared with manually tuned I controller. Simu- lation results revealed that the performance of the GA optimized PID controller is found to be the best amongst all three controllers. Further, sensitivity analysis is carried out to access the robustness of the controllers. Ó 2014 Elsevier Ltd. All rights reserved. Introduction Anticipating the energy crisis due to continued depletion of the world’s most valuable fossil energy resources and environmental hazards to be faced in the coming decades, concentrating solar thermal technology has been recognized as a promising candidate to provide critical solutions to global energy problems within a relatively short time frame without or with minimum carbon emission. Among all the renewable technologies that exist for large-scale power production today and for the next few decades, solar thermal technology is perhaps the best option to make signif- icant contributions of clean energy because of its use of relatively conventional technology and ease of scale-up [1]. To date, major solar thermal technologies include solar power tower, solar para- bolic trough, solar dish-engine, linear fresnel systems and zero to low concentration low temperature solar thermal systems. Out of these solar thermal technologies dish-Stirling solar thermal system is the most suitable one for stand-alone applications, because of modular design and the highest record for solar-to electric energy conversion efficiency among all solar thermal technologies. How- ever, the detail study on the dynamic performance of controllers of an autonomous hybrid energy system with dish-Stirling solar thermal system is not yet reported. Actually dish Stirling solar thermal technology is one of the old- est solar technologies. There are number of past and current dem- onstration projects, mostly in Europe, Japan, Australia and in USA [2,3]. All dish Stirling system deployments are reported in [4,5]. During last 20 years, eight different dish-Stirling systems ranging from 2 to 50 kW have been constructed by companies in the United States, Germany, Japan and Russia [6]. A plant with installed capacity 1.5 MW is in operation in Peoria, AZ, and plats with rated capacity of several hundred megawatts are in the planning stages [7]. In August 2005, Southern California Edison entered into an agreement with Stirling Engine Systems (SES) for purchasing power for 20-years using parabolic dish units of capacity between 500 and 850 MW (producing 1182–2010 GW h per year). Same year in September, SES publicized a contract with San Diego Gas & Electric to provide between 300 and 900 MW of solar power using the dish technology. Among operational solar dish systems around the world, 3 kW plant by Infinia Corp. and 10 kW by Schlaigh–Bergermann und Partner up to 150 kW by Stirling Energy Systems or Wizard Power Pty [4] are worth mentioning. There are few more large projects currently under planning and construction that are worth highlighting because of their significant power size. These projects use Stirling Energy Systems technology and are located in the USA with an installed capacity of 750 and 850 MW and in India using Infinia Corp. Technology with a capacity of 9–10 MW [8]. Other than these, two dish Stirling systems, which are developed and expected to be in operation in commercial scale in 2010: the Euro Dish from Schlaich– Bergermann at Eskom in South Africa and Partner (SBP) and the http://dx.doi.org/10.1016/j.ijepes.2014.06.006 0142-0615/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Mobile: +91 9435172774; fax: +91 3842 233797. E-mail addresses: dulal_nit@yahoo.co.in (D.Ch. Das), nidulsinha@hotmail.com (N. Sinha), anjan_kumarroy@rediffmail.com (A.K. Roy). Electrical Power and Energy Systems 63 (2014) 485–498 Contents lists available at ScienceDirect Electrical Power and Energy Systems journal homepage: www.elsevier.com/locate/ijepes