An Architecture for Local Energy Generation Distribution and Sharing
The United States electricity grid faces significant problems resulting from fundamental design principles that limit its ability to handle the key energy challenges of the 21 st century. We propose an innovative electric power architecture, rooted in lessons learned from the Internet and microgrids, which addresses these problems while interfacing gracefully into the current grid to allow for non-disruptive incremental adoption. Such a system, which we term a “LoCal” grid, is controlled by intelligent power switches (IPS), and can consist of loads, energy sources, and energy storage. The desired result of the proposed architecture is to produce a grid network designed for distributed renewable energy, prevalent energy storage, and stable autonomous systems. We will describe organizing principles of such a system that ensure well-behaved operation, such as requirements for communication and energy transfer protocols, regulation and control schemes, and market-based rules of operation.
The electric grid in the United States faces numerous challenges for effective power delivery in the 21 st century. As growth of demand continues, it becomes increasingly difficult to retrofit an aging system to supply sufficient power with an adequate margin for maintaining stability while meeting contingencies [1, 2]. Furthermore, power systems must be sized to handle peak demand levels, which are significantly higher than average demand and may be reached only a few hours a year [3]. Unfortunately, growth in peak demand has continued to outpace growth in transmission capacity over the last 20 years, as shown in Fig. 1 [1]. In addition to aggregate power problems, specific corridors that have seen disproportionate increases in demand are becoming especially congested [4]. These problems are exacerbated by the fact that the challenge of successfully delivering power has in general become more difficult as the size and complexity of the system has grown [5]. The current architecture of the power grid also poses problems for generating a significant portion of our energy needs from renewable sources. The grid was designed for central, large-scale, predictable power sources such as coal, natural gas, and nuclear power plants and is not able to accommodate high penetration of intermittent sources without drastically sacrificing stability [6]. The maximum amount of intermittent sources that can be utilized is estimated to be about 20% to 25% of total demand using established control methods [7], though certain methods of operation may increase this limit, such as forecasting [8] and balancing with demand response capabilities [9]. This poses a fundamental challenge to the integration and penetration of renewable sources in the future. Furthermore, the distribution system is designed for one-way power flow – from central power plants to distributed loads [10]. The introduction of a large number of distributed sources, such as photovoltaic cells on residential roofs, is not easily manageable and adds to stability liabilities in the operation of the grid. [6, 10]. These problems cannot be easily solved under the current electric grid paradigm. Building additional transmission capacity is costly, time-consuming, and fraught with politics [11]. Expanding the current system will, in the long run, only increase its complexity. Short of a costly radical restructuring of the grid, its architecture remains one of the principal barriers to achieving the levels of renewable energy penetration that are necessary to meet long term energy goals
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