Research and Design in Unified Coding Architecture for Smart Grids

 Standardized and sharing information platform is the foundation of the Smart Grids. In order to improve the dispatching center information integration of the power grids and achieve efficient data exchange, sharing and interoperability, a unified coding architecture is proposed. The architecture includes coding management layer, coding generation layer, information models layer and application system layer. Hierarchical design makes the whole coding architecture to adapt to different application environments, different interfaces, loosely coupled requirements, which can realize the integration model management function of the power grids. The life cycle and evaluation method of survival of unified coding architecture is proposed. It can ensure the stability and availability of the coding architecture. Finally, the development direction of coding technology of the Smart Grids in future is prospected

Systematic categorization of optimization strategies for virtual power plants

Due to the rapid growth in power consumption of domestic and industrial appliances, distributed energy generation units face difficulties in supplying power efficiently. The integration of distributed energy resources (DERs) and energy storage systems (ESSs) provides a solution to these problems using appropriate management schemes to achieve optimal operation. Furthermore, to lessen the uncertainties of distributed energy management systems, a decentralized energy management system named virtual power plant (VPP) plays a significant role. This paper presents a comprehensive review of 65 existing different VPP optimization models, techniques, and algorithms based on their system configuration, parameters, and control schemes. Moreover, the paper categorizes the discussed optimization techniques into seven different types, namely conventional technique, offering model, intelligent technique, price-based unit commitment (PBUC) model, optimal bidding, stochastic technique, and linear programming, to underline the commercial and technical efficacy of VPP at day-ahead scheduling at the electricity market. The uncertainties of market prices, load demand, and power distribution in the VPP system are mentioned and analyzed to maximize the system profits with minimum cost. The outcome of the systematic categorization is believed to be a base for future endeavors in the field of VPP development

A generalized optimal power flow program for distribution system analysis and operation with distributed energy resources and solid state transformers

The present distribution system is gradually trending towards a smart grid paradigm with massive development of distributed energy resources (DER), advanced power electronics interfaces, and a digitalized communication platform. Such profound changes bring challenges as well as opportunities for an entity like the distribution network operator (DNO) to optimally operate DERs and other controllable elements to achieve higher levels of energy efficiency, economic benefits, supply reliability and power quality. The major contribution of this dissertation is in the development of a generalized three-phase optimal power flow (OPF) program in a novel control scheme for future distribution system optimization and economic operation. It is developed based on primal-dual interior point method (PDIPM). The program is general enough to model comprehensive system components and topologies. The program can also be customized by user-defined cost functions, system constraints, and new device, such as solid state transformers (SST). An energy storage optimal control using dynamic programming is also proposed to coordinate with the OPF based on a pricing signal called the distribution locational marginal price (DLMP). The proposed OPF program can be used by the DNO in an open access competitive control scheme to optimally aggregate the energy mix by combining the profitability of each resource while satisfying system security constraints --Abstract, page iv

Large-scale security constrained optimal reactive power flow for operational loss management on the GB electricity transmission network

This thesis was submitted for the degree of Engineering Doctorate and awarded by Brunel University, 22/12/2010.The transmission of power across the GB transmission system, as operated by National Grid, results in inevitable loss of electrical power. Operationally these power losses cannot be eliminated, but they can be reduced by adjustment of the system voltage profile. At present the minimisation of active power losses relies upon a lengthy manually based iterative adjustment process. Therefore the system operator requires the development of advanced optimisation tools to cope with the challenges faced over the next decade, such as achieving the stringent greenhouse gas emission targets laid down by the UK government, while continue to provide an economical, secure and efficient service. To meet these challenges the research presented in this thesis has developed optimisation techniques that can assist control centre engineers by automatically setting up voltage studies that are low loss and low cost. The proposed voltage optimisation techniques have been shown to produce solutions that are secured against 800 credible contingency cases. A prototype voltage optimisation tool has been deployed, which required the development of a series of novel approaches to extend the functionality of an existing optimisation program. This research has lead to the development of novel methods for handling multi-objectives, contradictory shunt switching configurations and selecting all credible contingencies. Studies indicate that a theoretical loss saving of 1.9% is achievable, equivalent to an annual emissions saving of approximately 64,000 tonnes of carbon dioxide. A novel security constrained mixed integer non-linear optimisation technique has also been developed. The proposed method has been shown to be superior to several conventional methods on a wide range of IEEE standard network models and also on a range of large-scale GB network models. The proposed method manages to further reduce active power losses and also satisfies all security constraints.EPSRC and National Gri

A robust method for topology analysis of unbalanced and balanced distribution power networks

Potreba da se minimalizuje vreme otkaza usluge distribucije električne energije motivisala je češću upotrebu kompozitne prekidačke i privremene opreme u elektrodistributivnoj mreži. To je dovelo do pojave kompleksnijih topoloških slučajeva koje su postojeća rešenja za topološku analizu imali poteškoće da procesiraju. U ovom radu predloženo je jedno sveobuhvatno rešenje za topološku analizu uravnoteženih i neuravnoteženih elektrodistributivnih mreža. U osnovi rešenja je topološki model koji predstavlja matematičku apstrakciju elektrodistributivne mreže u vidu grafa, gde su svi relevanti fizički uređaji direktno modelovani koristeći čvorove i grane. Graf je memorisan pomoću matrične strukture koja definiše povezanost čvorova pojedinačnim fazama, modelujuću pored statičke konektivnosti i dinamičke podatke kao što su trenutno stanje prekidačke opreme i prisutnost privremene opreme. Tako unapred pripremljeni podaci omogućavaju efikasnu topološku analizu koja vrši pretragu grafa po širini. Rezultat topološke analize je široki skup topoloških informacija (formiranje ostrva, slojevite strukture mreže, stanja energizacije, aktivne faznosti, itd.) koje se mogu direktno primeniti na fizičku opremu. Prodloženo rešenje verifikovano je na različitim primerima stvarnih i testnih elektrodistributivnih mreža. Robusnost rešenja demonstrirana je na topološkim slučajevima s kojim su postojeća rešenja imala problema pri procesiranju.A need to minimize the duration of outage in the distribution network has motivated the more frequent use of composite switching equipment and temporary equipment. This has led to the creation of complex topological cases that existing solutions have a problem to process. A comprehensive solution for topological analysis of balanced and unbalanced distribution networks is proposed in this paper. The solution is based on a topological model that represents a mathematical abstraction of the distribution network in the form of a graph, where all relevant physical devices are directly modeled using buses and branches. The graph is memorized using a matrix structure that defines the logical connection between buses per single phase, taking into account static connectivity, current state of switching equipment and the presence of temporary equipment. The network data prepared in this way enable an efficient topological analysis that searches the graph per layers. The result of topological analysis is a wide set of topological data (islands, layered network structure, energization states, active phases, loop detection etc.) that can be directly applied to real physical equipment. The proposed solution was verified on various examples of real and test distribution networks. The robustness of the solution is demonstrated on topological cases which existing have a problem to process