This paper presents an innovative approach for the understanding and control of grid-connected hybrid micro-generation systems (HMS) without energy storage, to supply electricity to a group of homes designated as 'Sustainable block'. The initiative is based on an effort to integrate non-conventional renewable energies (NCRE) through distributed generation (DG) projects intended for remote and rural communities in Chile and South America, where electricity supply is both expensive and often times unreliable. This may be due to equipment malfunction, line faults and/or harsh climatic conditions or other natural phenomena like earthquakes, all of which can undermine the electric power distribution networks. Here a systems thinking (ST) and cybernetics approach is employed which looks at grid-connected microgrids supplying power to local loads as intrinsically dynamic, complex adaptive systems (CAS). Moreover, such systems can be viewed and approached as a complex sociotechnical system, wherein the energy users ought to play a crucial role as 'active loads' within the sustainable block to which the grid-tie microgrid is coupled. Building upon this theoretical framework, a set of coordination and supervisory control strategies for renewable microgrids is presented based on homeostatic control (HC) principles introduced by Schweppe et al. Homeostatic control of power systems. In: Fourth energy monitoring and control system conference. Norfolk, VA: November; 1979. The approach is intended to study and eventually develop new forms of sustainable renewable energy technologies (RETs) for DG of electricity and heat, working in parallel with the grid and offering new choices and benefits to energy users everywhere. A concrete theoretical model is proposed and the algorithms depicting the strategies are explained and compared through simulation analysis. Unlike what is available in the literature on sustainability, and looking at what is missing in regards to HMS as sustainable energy systems (SES), this paper offers an entirely new and significant perspective in terms of design and operation of such systems. First the concepts of sustainability and SES applied to HMS are explored, finding that the large majority of the mainstream analysis reviewed on the subject is focused on socio-economic, environmental, and regulatory issues rather than on the systemic, technical and operational aspects of such systems, as this paper does, and how HC, energy efficiency (EE), and a novel approach to energy supply and consumption equilibrium based on homeostasis can help build more sustainable HMS. Results are presented which confirm the hypotheses underlying the strategies employed and the model predictability, showing that SES are indeed possible and feasible. Discussion and recommendations are also offered stressing the fact that sustainability is essentially a systemic property and operational in nature, rather than explained by exogenous factors. (C) 2014 Elsevier Ltd. All rights reserved.
