Imre Lendak

Algorithms in electric power system one-line diagram creation

This paper analyzes various algorithms for the automatic generation of electric power system one-line diagrams. Historically these one-line diagrams were created manually. As these diagrams can be large, their manual creation takes a lot of time and resources, and it is also prone to errors. One possible solution to this problem is the automatic generation of one-line diagrams. Automatic visualization can be performed by existing rule-based algorithms, or if the network is modeled by a mathematical graph, then the problem can also be solved by graph drawing algorithms. Initial results achieved with soft computing algorithms will also be shown. We discuss the similarities, differences and applicability of these different algorithms in automatic one-line diagram generation. The final goal is to find the most suitable algorithm for the automatic generation of visually pleasing one-line diagrams, which allow dispatchers and engineers working in control centers a higher level of efficiency in performing their everyday tasks.

RESTful web services and the Common Information Model (CIM)

This paper shows one possible way to enhance power system software integration by combining RESTful web services (RESTful WS) and the IEC 61970 set of standards. We also discuss the differences between SOAP and RESTful web services in the context of this research. We propose a web service, which wraps the resource oriented power system data model defined in the IEC 61970–301 Common Information Model (CIM) and the generic query interface defined in IEC 61970–403 Generic Data Access (GDA). We will demonstrate that a RESTful WS atop of existing IEC 61970 standards can significantly loose the couplings between different software packages used in power system control centers. We have performed tests on real life power system data models (some used in CIM interoperability tests) to make the tests more realistic. The proposal depicted in this paper provides another powerful tool for creating truly distributed power system software solutions.

Simulation environment for investigating crowd-sensing based urban parking

This paper introduces a simulation environment developed for analyzing crowd-sensing based applications in the Smart City application domain. As a case study, an urban parking application scenario is investigated and presented. In this scenario, smart citizens collect and share parking related events, such as leaving or occupying a free parking spot. These events can be presented on a real-time city map and used in navigation software, thereby helping others alleviate parking related issues, such as the time spent while cruising for parking. The simulation environment, implemented in Java, allows to investigate and assess the critical user base of crowd-sensing based smart city applications, and the requisites (benefits, challenges) of introducing such applications. Our simulation results show that considerable gain (approx. 15%) can be achieved in the cruising time even with relatively low (30%) user base in a medium size city (Novi Sad, Serbia). Moreover, the proposed simulation environment can be used also in real field measurements by replacing/extending input data from real users.

Algorithm for adaptive Smart Grid visualization

This paper describes an algorithm which automatically generates adaptive one-line diagrams of large electric power distribution systems. The proposed algorithm is different from similar algorithms as it performs adaptive one-line diagram generation, which differ for various zoom levels, showing only the most important objects (e.g. substations, pole switches, power lines) on small zoom levels and gradually adding the less important objects (e.g. lateral parts of the network) as the level of zoom rises, while maintaining the relative positions of the more important objects. The algorithm represents the distribution network as a mathematical graph and visualizes it by utilizing the divide-and-conquer and branch-and-bound algorithms. The algorithm was tested on partial, real life electric power distribution systems of up to 100 objects and it generated visually pleasing one-line diagrams.

A HYBRID GENETIC ALGORITHM FOR PARTITIONING OF DATA MODEL IN DISTRIBUTION MANAGEMENT SYSTEMS

In this paper, we propose a Hybrid Genetic Algorithm for data model partitioning of power distributionnetwork. Analytical functions are the core of Distribution Management Systems (DMSs). Efficient calculation of thefunctions is of the utmost importance for the DMS users; the necessary preconditions for the efficient calculation areoptimal load balancing of processors and data model partitioning among processors. The proposed algorithm is appliedto different real models of power distribution systems. It obtains better results than classical evolutionary algorithms(Genetic Algorithm and Particle Swarm Optimization). The Hybrid Genetic Algorithm also achieves better results thanmultilevel algorithm (METIS) in cases of small graphs. http://dx.doi.org/10.5755/j01.itc.40.4.981

Applicability of RESTful web services in control center software integrations

This paper shows the result of an analysis pertaining to the applicability of RESTful web services (RESTful WS) in solving various software and data integration scenarios in control centers for the electric power system domain. There are many possible ways to enhance power system software/data integration by combining RESTful WS and the IEC 61970 set of standards. The goal of this paper is to highlight those lines of integration in control centers, where the benefits of leveraging RESTful WS are most noticeable. The importance of selecting the most prominent integration scenarios from the viewpoint of RESTful WS stems from the fact, that not all integration problems are naturally fitted for RESTful WS. Assuming a type of RESTful WS, which wraps the resource oriented power system data model defined in the IEC 61970–301 Common Information Model (CIM) and the generic query interface defined in IEC 61970–403 Generic Data Access (GDA), the paper demonstrates that such a RESTful WS may be successfully utilized in many concrete integration situations. As an added advantage, a RESTful WS atop of existing IEC 61970 standards can significantly loose the couplings between different software packages used in power system control centers. We have realized several pilot projects using real life power system data models (some used in CIM interoperability tests) to assert the outcome of our feasibility study. This study clearly shows that RESTful web services are a powerful tool for solving numerous power system software and data integration problems in control centers.

RESTful access to power system state variables

This paper shows one possible way to enhance power system software integration by leveraging RESTful web services in the process of publishing power system state variables, i.e. the results of simulation functions used in power system analysis.1 Different simulation functions are executed in power system control centers with various goals: optimize network utilization, find critical elements, plan future extensions, etc. Most of these functions base their operation on the results of state estimation and/or load flow. The implementations of these base functions most often come from different software vendors using, in general, different communication mechanisms. Even if the base functions are provided by a sole vendor, the various functions relying on the results of these base functions are most probably offered by different software companies. For this reason, it is necessary to have a standardized method for exchanging state variables between parties. In this paper, we propose a lightweight mechanism, reminiscent to the mechanisms of the World Wide Web, for publishing state variables. The proposition is actually based on existing IEC standards and drafts. The final goal is to allow solution providers to develop a planning and simulation environment for control centers utilizing components made by separate organizations.

Algorithm for distribution substation area visualization

This paper presents a one line diagram generation algorithm capable of drawing multiple feeders supplied by a single (electric power) distribution substation. First the substation area is represented with a mathematical graph. A combination of iterative and recursive methods are applied to draw that graph. There are two iterative steps: the whole graph is partitioned into feeders and the main branch of each feeder is further partitioned into subgraphs of one or more vertices around the vertices corresponding to the nodes of the main branch. There is one recursive step, namely each feeder might contain non-trivial, lateral branches which are recursively drawn with the same algorithm. The algorithm automatically arranges multiple feeders around the supply substation. The drawn direction of each feeder can be different, either left, right, up or down. The algorithm was tested on multiple distribution substation areas exported from three different real life (European) distribution network models. It produced visually pleasing diagrams even for graphs with more than 1000 vertices. Each auto-generated diagram was assessed with a diagram assessment formula specifically developed by the authors for measuring the quality of the generated one line diagrams.

Electric power distribution system visualization with graph partitioning

This paper presents an electric power distribution system (EPDS) visualization algorithm which performs graph partitioning before generating the visual representations, i.e. one line diagrams. The proposed algorithm is different from similar algorithms as it performs graph partitioning to reduce the solution space. The partitioning step is necessary because modern EPDS can consist of thousands of distribution transformers, pole switches and line segments. After the partitioning step, in its second phase, the algorithm lays out the subgraphs and then combines the drawings into complete one-line diagrams. During the experiments, the partitioning and layout phases were performed with various combinations of the genetic and branch and bound algorithm. The algorithm was tested on partial, real life electric power distribution systems of up to 150 objects and it generated visually pleasing one-line diagrams.

Algorithm for cataloging topologies in the Common Information Model (CIM)

This paper presents a novel algorithm for finding the catalog of topologies in a power systems model in the Common Information Model (CIM) format. The algorithm prepares the models of complex, large-scale power systems (e.g., Smart Grids with renewable energy sources) and allows analytic Distribution Management System (DMS) functions to achieve high performance and optimize the power system operation in real time. It utilizes the Ullmann graph isomorphism algorithm to find unique topologies. In addition, it is optimized for parallel execution on 64-bit, multi-processor computers. Its ability to handle large amounts of data was verified on detailed, real-life electric power system data.