Gelli Ravikumar

CIM oriented database for topology processing and integration of power system applications

Although the standards-based systems integration of utility software applications using the domain data standard common information model (CIM) exists, many utilities are facing difficulties in managing of data exchanges among software application systems due to lack of standard oriented database management systems. The standard oriented database can be built from the CIM object oriented model using object-relational mapping (ORM). The generic design of ORM can handle object oriented model mapping to any database schema semantics. This paper presents a CIM oriented database (CIMODB) design through the object-relational mapping (ORM). The flexibility of data moving between object-oriented paradigms and relational database paradigms is achieved with the use of ORM concepts. Furthermore, the paper explores the integration of upstream power system applications with the proposed CIMODB, such as, topology processing, load-flow analysis, and more power system studies at the control center level from the legacy vendor software systems. A case study is illustrated to elaborate the CIMODB concept on the 400kV 20-substation Maharashtra network, which is the part of western region in India.

Graphics Model for Power Systems Using Layouts and Relative Coordinates in CIM Framework

Summary form only given. Conventional power system graphic applications use absolute coordinates approach, in which the objects are positioned with respect to a common origin. This can result in problems of re-adjustment and re-alignment in the network and substation diagrams when editing or merging the graphics. This paper introduces the notion of layouts and proposes a graphics model to facilitate positioning of graphical elements relative to each other in a hierarchy of layouts, there by, making the network diagrams flexible, sharable and extensible. This proposed graphics model, expressed in unified modeling language (UML) is shown to be compatible with the existing common information model (CIM) graphics model IEC 61970-453. Consequently, the need for extension of CIM graphics model is justified and an extension is proposed. Another key feature of the proposed model is configurability. Since, the necessary parameters are explicitly modeled, the user only needs to provide configuration information describing the hierarchical connectivity of the substation or the network. The absolute coordinates can be calculated from the configuration and the power system diagrams can be auto-generated. This paper demonstrates the above benefits highlighting the technologies for implementation. Case study on 400kV 20-substation diagrams of Maharashtra system in India is presented.

Business Process Model for Deriving CIM Profile: A Case Study for Indian Utility

Common information model (CIM) in vogue represents transmission and distribution components, and market operations in the perspective of electrical system, as unified modeling language (UML) objects. UML is object centric. CIM can offer interoperability and facilitate model exchange for large systems and is being adopted by many utilities. However, dealing effectively with multiple business processes is the backbone of the restructured power systems. Since CIM lacks chronological process sense, this has to be superimposed on CIM models, which is not easy due to inherent limitations of UML. To overcome this, this paper proposes to utilize business process modeling notation (BPMN) standards as a kind of pre-processor. BPMN is used to represent process centric interoperability requirements as business objects. UML object representation in CIM model is derived subsequently from it. The proposal is illustrated with an application use case-deriving CIM model of day-ahead market (DAM) transaction of distribution company, from its business process representation. Semantic model of DAM transaction using CIM IEC 62325 (Markets) and extensions required are presented with a sample Indian system. DAM models in BPMN and CIM can be utilized to build an efficient software application.

Towards CIM implementation challenges in control centers worldwide and Indian power grid

Although common information model (CIM) standard has been already a recognized power system domain standard, utilities are facing difficulties in the process of upgrading their software systems on CIM framework. Significant challenges faced by utilities are due to various issues such as legacy of distinct names given to the same power system resource, data silos within different power system applications referring to common network resources and multiple points of data entry. Besides, at an interconnected multi regional network operation, every regional operator responsible for authorizing their internal network model. Such a decentralized model authority scenario realizes ease of managing and monitoring complex power networks. Despite having these advantages, due to having predefined local IDs of power system resources in the internal network models, model merging and splitting are cumbersome while exchanging their models across other regions. These challenges are more prominent in complex power system networks like largely interconnected Indian power grid. Indian power grid is now moving towards adopting CIM framework at regional control centers. This paper presents a comprehensive literature survey on CIM implementations and its practices at power utilities. Moreover, the paper discusses typical challenges like network model exchange and naming schema in the context of Indian power grid.

Making Distribution Automation Work: Smart Data Is Imperative for Growth

Deregulation of the power industry and the shifting of investment into different types of generation capacity such as distributed energy resources have complicated today?s power grid and pushed it nearer to its operating limits. As a consequence, operations of the power grid have become significantly more dependent on complex computer-based, analytically intensive operating procedures. This article explains how common information model standards enable the acquisition and integration of data from a variety of sources and time frames, as required by utility analytics, to operate the grid close to capacity.

CIM oriented graph database for network topology processing and applications integration

Though CIM brings an integration of proprietary software applications of a utility, managing a sheer volume of data between the software application systems is still challenging for utility operators. With the advent of high performance database technologies and real-time big-data processing tools available, CIM oriented database can play important role in the operation and processing of the power system data. As the power system resembles connected-data, the choice of the database technology has to be based on the performance measures such as high-speed data retrieval of the connected-data and efficient storage. This paper presents a CIM oriented graph database (CIMGDB) by the object-graph mapping methodology. The integration of the CIMGDB with power system applications is discussed by the developed implementation architecture. The network topology processing (NTP) application is implemented on the CIMGDB. The NTP is tested on the six IEEE test systems and on one practical power system network. The six IEEE test systems are considered in evaluating and comparing the time complexity of CIMGDB with the CIM oriented relational database framework. The practical power system network is considered to demonstrate the implementation architecture and the CIMGDB integration with power system applications.

Towards CIM based control centers

New generation of future power system control centers need a paradigm shift in their utility IT operations, coordinated use of applications and the architectural designs to meet new challenges. However, literature on comprehensive architectural design and implementation towards this direction is scarce. In this paper, an architecture design and implementation aspects are demonstrated for integrating applications and for migrating legacy control centers towards future generation smart grid. Appropriate adoption of open standards such as the common information model (CIM) is endorsed. Though the CIM standard is matured at model level, many utilities are facing difficulties in managing data exchanges. As a consequence of the lack of integration capabilities, difficulties are faced in delivering prompt and accurate decisions in response to grid disturbances. Standards-based integration of systems and applications has become imperative. This paper presents an approach for integrating inter-utility and intra-utility application systems through CIM framework. The architecture comprises components for data integration & access, CIM based plug-in adapters and third-party application integration. The details of this architecture along with the intricate relationships between various layers and the open source technologies are described. The proposed architecture includes components such as CIM XML creators, CIM XML database adapters, CIM XML application adapters for power system applications. The applications over this architecture work as web applications. A case study involving WR 400 kV network is illustrated to demonstrate migration strategy. Another case study involving load flow and topology processing applications is illustrated to elaborate the proposed architecture on data from a 400 kV 20-substation state network.

Representation of short-term open access transactions using common information model

Short term open access (STOA) transactions are one of the important mechanisms for exchange of power on Indian national grid. Currently, STOA is operated by five regional load despatch centers, leading to differences in representation of STOA transaction information. This paper presents the modeling of STOA using common information model (CIM). Use-case addressed includes, generation of a CIM/XML report which presents the STOA data for a given utility. The proposed system consists of five components namely, data acquisition, data conversion to CIM, data validation, STOA modeling in CIM and data visualization. The STOA transactions of the Western and Southern regions of India for the year 2011 have been used for building the database. The system is developed using python programming language, enterprise architect, and CIMTool for validation. The output generated creates a better understanding of market situation and thus is useful for the traders, generation utilities, discoms and system operators.

A Common Information Model Oriented Graph Database Framework for Power Systems

Common Information Model (CIM) is widely adopted by many utilities since it offers interoperability through standard information models. Storing, processing, retrieving, and providing concurrent access of the large power network models to the various power system applications in CIM framework are the current challenges faced by utility operators. As the power network models resemble largely connected-data sets, the design of CIM oriented database has to support high-speed data retrieval of the connected-data and efficient storage for processing. The graph database is gaining wide acceptance for storing and processing of largely connected-data for various applications. This paper presents a design of CIM oriented graph database (CIMGDB) for storing and processing the largely connected-data of power system applications. Three significant advantages of the CIMGDB are efficient data retrieval and storage, agility to adapt dynamic changes in CIM profile, and greater flexibility of modeling CIM unified modeling language (UML) in GDB. The CIMGDB does not need a predefined database schema. Therefore, the CIM semantics needs to be added to the artifacts of GDB for every instance of CIM objects storage. A CIM based object-graph mapping methodology is proposed to automate the process. An integration of CIMGDB and power system applications is discussed by an implementation architecture. The data-intensive network topology processing (NTP) is implemented, and demonstrated for six IEEE test networks and one practical 400 kV Maharashtra network. Results such as computation time of executing network topology processing evaluate the performance of the CIMGDB.

Taxonomy of PMU Data Based Catastrophic Indicators for Power System Stability Assessment

Though extensive work is reported on various catastrophic indicators for the assessment of power system stability, the comparative assessment has not received much attention by the researchers. With the advent of WAMS technology and near real-time tools available, these indicators can play an important role in operation and control of the system. The choice of the indicator(s) has to be based on the performance measures (accuracy, reliability, security, mis-detection, false-alarm, and correctness), which use a common platform for evaluation. This companion paper presents a critical review of the catastrophic indicators and computes the performance measures to assess the indicators, which is illustrated by an implementation architecture. The approach starts by generating a contingency dataset of a network, followed by obtaining the network measurements to the contingency dataset. These measurements are used as an input to the indicators for detecting stability/instability cases. The performance measures are computed to each indicator for their assessment. In addition to the above performance measures, robustness and sensitivity are obtained to each indicator. The IEEE 39 and IEEE 118 test networks are considered for comparing the performance measures. Additionally, 50-machine 145-bus system is used to demonstrate the applicability of indicators on practical systems. This work provides systematic taxonomy and insight into various indicators bringing out salient features on a comparative note to help decision makers to make suitable choice of indicator(s) for their system.