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The concept of community microgrid distribution system presents a new framework for operation and management of the future distribution systems with various operating constraints and a business model. It aims at extending the benefits of traditional microgrid by sharing the energy resources among multiple partners. Peer-to-peer (P2P) energy trading model seems to be one of the suitable models for energy trading in the future community microgrid distribution system. This paper proposes a hierarchical peer-to-peer (HP2P) energy trading framework for future community microgrid distribution networks to provide efficient energy trading in the microgrid energy market. The proposed HP2P framework is applied to a sample community microgrid distribution system. It results in cost saving and hence its effectiveness is verified by simulation study. Accepted version

In demand side management electricity consumers are systematically encouraged by a load serving entity (LSE) to adjust their electricity demand to reduce overall costs. Li et al. [1] have presented such an iterative demand response program. In each iteration it sends price signals to the consumers against their demands for each hour of the day ahead, and smart consumer appliances adjust their usage accordingly to maximize their utility given the prices. The price signal is the marginal cost based on a single quadratic and piecewise smooth cost function. We extend previous work to allow multiple cost functions one for each supplier, and require that the LSE optimizes procurement jointly with the demand response. The price signal is then based on the optimal cost of procurement from all suppliers, computed using sequential quadratic programming (SQP). However, when the number of cost functions grows computing the price signal in each iteration becomes a bottleneck. Therefore, we also introduce an approximation technique based on knowledge compilation, in which the procurement problem is first represented in discrete form in propositional logic, and compiled into a tractable form known as decomposable negation normal form (DNNF). The DNNF is then used for efficient computation of near optimal prices in each iteration. Refereed/Peer-reviewed

Energy management system of a microgrid (MG) is responsible for determining its optimal generation schedule which fulfills the load demand while satisfying several constraints related to the equipment and system operation. When many MGs are interconnected, it is sometimes preferable to exchange power among MGs in such a manner so as to minimize their operating cost while reducing dependency on the main grid. This paper proposes a cost based power sharing scheme combined with a more realistic EMS scheme. These two schemes are implemented in two control layers which communicate with each other to optimize MG operation. Simulation results demonstrate the benefits of the proposed approach. Accepted version

Significant evolution of distribution system, including distributed generation, microgrids and remote- controlled switches (RCSs), lead to novel and effective distribution system restoration (DSR) strategies. This paper proposes a resilience-oriented reconfiguration method to restore service to interrupted customers in distribution system as expeditious as possible after major blackouts. A structural model with virtual node and branches is provided to describe the radial structure constraint. The energy limits within microgrids are taken into considerations to account for scarcity of generation resources. The optimization problem is formulated as mixed-integer second- order cone programming (MISOCP), which employs a convex representation of a distribution network model on the basis of the conic quadratic format of the power flow equations. Case study is implemented on a modified 33-bus test system to verify the propose method. NRF (Natl Research Foundation, S’pore) Accepted version

This paper proposes a simple method of determining the size of excitation capacitance required to buildup a predetermined no load voltage for off-grid operation of a three-phase self-excited induction generator. The method is based on the combination of the principle of L-C resonance and non-linear magnetization characteristic of the generator. For given values of voltage and speed, the magnetizing reactance of the generator is first determined from the solution of a polynomial. The size of the excitation capacitance is then obtained from the principle of L-C resonance. The effectiveness of the proposed method is checked through a more sophisticated generator model where the electrical characteristics are represented by four first-order differential equations. The voltage build-up process in time domain is also investigated through the above model. The results obtained by the proposed method are also verified through an experimental setup consisting of a 1.5-kW induction machine and are found to be in very good agreement. Refereed/Peer-reviewed

This paper describes a simple and general method of evaluating the steady state characteristics of a single-phase self-excited induction generator operating in shunt, short-shunt and long-shunt configurations. The steady state problem of the generator for various operating configurations is first formulated in a very general way and expressed by a set of nonlinear equations. The formulated problem is then solved using a numerical based optimization routine given in MATLAB. The effectiveness of the proposed method is tested on a 1-hp, 220-V, single-phase induction generator operating in shunt, short-shunt and long-shunt configurations. Simulation results obtained by the proposed method are also compared with the corresponding actual values found through an experimental setup and are observed to be in very good agreement.

The Long Island Power Authority (LIPA) requires accurate and accessible data to optimally manage its assets as well as its service providers. From LIPA's perspective of an asset owner and manager, four key performance areas must be considered: technical performance (such as reliability of assets and system), financial performance (cost and revenue), customer satisfaction, and regulatory compliance. Data stemming from each of these areas is interrelated and needs to be understood in the context of the whole. Therefore LIPA prefers vendors and service providers to fit their systems into LIPA's enterprise based upon predefined and well-documented interfaces. To optimize cost and efficiency, these interfaces need to be based on useful industry standards. One such standard is the Common Information Model (CIM), which has been used on several projects in recent years. While these projects have achieved most of their project goals, there is still significant room for improvement regarding company-wide data flow objectives. Consequently, LIPA has recognized that Service Oriented Architecture (SOA) based on company-wide and standards-based data modeling is an essential component of longer term business solution. This paper describes the experience and motivation driving LIPA's data management strategy and the methodology now being employed to implement it, which has at its core a CIM-based Enterprise Semantic Model (ESM). Refereed/Peer-reviewed