N. Chowdhury

A reliability test system for educational purposes-basic data

The IEEE Subcommittee on the Application of Probability Methods (APM) published the IEEE Reliability Test System (RTS) [1] in 1979. This system provides a consistent and generally acceptable set of data that can be used both in generation capacity and in composite system reliability evaluation [2,3]. The test system provides a basis for the comparison of results obtained by different people using different methods. Prior to its publication, there was no general agreement on either the system or the data that should be used to demonstrate or test various techniques developed to conduct reliability studies. Development of reliability assessment techniques and programs are very dependent on the intent behind the development as the experience of one power utility with their system may be quite different from that of another utility. The development and the utilization of a reliability program are, therefore, greatly influenced by the experience of a utlity and the intent of the system manager, planner and designer conducting the reliability studies. The IEEE-RTS has proved to be extremely valuable in highlighting and comparing the capabilities (or incapabilities) of programs used in reliability studies, the differences in the perception of various power utilities and the differences in the solution techniques. The IEEE-RTS contains a reasonably large power network which can be difficult to use for initial studies in an educational environment.

A reliability test system for educational purposes-basic results

A set of basic reliability indices at the generation and composite generation and transmission levels for a small reliability test system are presented. The test system and the results presented have evolved from reliability research and teaching programs. The indices presented are for fundamental reliability applications which should be covered in a power system reliability teaching program. The RBTS test system and the basic indices provide a valuable reference for faculty and students engaged in reliability teaching and research

Operating reserve assessment in interconnected generating systems

It is shown that the two risks concept can be used to determine the spinning reserve requirements of a multiarea interconnected system configuration. This is a probabilistic technique which takes into account the system parameters which directly or indirectly influence the system reliability. It is concluded that the use of a single system risk and an interconnected system risk provide valuable insight into the benefits of interconnection. These concepts are illustrated by application to two radially interconnected power systems. >

A Case-Based Windows Graphic Package for the Education and Training of Power System Restoration

This paper presents a case-based Windows graphic package developed by the authors for the education and training ofpower system restoration. In order to overcome the inherent complexities associated with a restoration switching sequence, a case-based reasoning (CBR) algorithm has been developed. An object-oriented Windows-based graphical user interface (GUI) has been developed to communicate with the expert system and to visualize outputs. Simulation results on a part of the Saskatchewan Power (SaskPower) network have been presented in this paper. The restoration practices of the SaskPower network have been collected and stored in a knowledge database called case library. The power flow and the implementation risk analysis tools have been incorporated into the expert system. A risk analysis tool has been used to determine the implementation risk due to the imperfect switching actions. Using the GUI, a user can simulate a blackout event on the system under study. The expert system proposes a restoration proposal after reasoning with the past solutions available in the case library. Using the power flow analysis tool, the user can check the system scenarios after the restoration proposal is implemented.

An artificial neural network based transmission loss allocation for bilateral contracts

The introduction of deregulation and the subsequent open access policy in electricity sector have opened up the door for power transactions between generators and bulk consumers under many different market-driven contractual forms including bilateral contracts. Long-term bilateral contracts are attractive to many parties who want to avoid price volatility. With bilateral contracts it becomes necessary to allocate transmission loss to respective transactions. An artificial neural network based transmission loss allocation method is presented in this paper. The method is computationally efficient and can provide solutions on a real-time basis. Most independent system variables can be used as inputs to this neural network which in turn makes the loss allocation process responsive to practical situations. Training and testing of this network have been done with the help of the IEEE 24-bus test system. A technique has been developed to expedite the convergence and to improve the accuracy of the results. Numerical examples on loss allocations for both peak and off-peak hours have been provided and compared with those obtained using another technique

Unit commitment in interconnected generating systems using a probabilistic technique

A probabilistic technique is presented which can be used to develop unit commitment schedules for continually changing loads in an interconnected power system configuration for a specified period. The technique is developed on the basis of each area in a multi-area configuration fulfilling one of two different risk criteria. This approach, which is known as the two-risks concept, was illustrated in a recent publication (R. Billinton and N.A. Chowdhury, see ibid., vol.3, p.1479-87, 1988). The unit commitment during a specified scheduling period is constrained by risk criteria and economic factors. Typical unit commitment cases are illustrated with numerical examples. >

Allocation of transmission losses in a deregulated power system network

Full deregulation would allow bilateral contracts between the suppliers and the buyers. This concept, however, leads to the confusion of transmission loss sharing and generation of the reactive power. Two methods, incremental load flow approach (ILFA) and marginal transmission loss approach (MTLA), have been developed to determine a generators share of transmission loss in a fully deregulated power system. ILFA is very simple and employs the load flow technique in an iterative way. MTLA is basically a mathematical modeling of the transmission losses based on Krons loss formula in a fully deregulated network. It calculates marginal increase in transmission loss due to an increase in load. These methods along with some numerical results have been presented in the paper.

A reliability test system for educational purposes-spinning reserve studies in isolated and interconnected systems

Operating reserve in a system is required to make the system capable of handling unforeseen load changes and possible outages of generation. The basic results of an assessment of operating reserve requirements in a small reliability test system are presented. Results are presented for both isolated and interconnected configurations. The results provide a basic understanding of probabilistic assessment of operating reserve requirements and can be included in a power system reliability teaching program. >

Export/import of spinning reserve in interconnected generation systems

Interconnected power systems may import energy and/or purchase spinning reserves from neighbors in order to reduce risk. A probabilistic technique is presented to assess import and/or spinning reserve purchase requirements of interconnected systems in order to overcome the effects of inadequate operating capacity on unit commitment risk. A unit commitment technique which can include options of spinning reserve purchase/sale is presented. A method of assessing the portion of the running cost in interconnected power systems due to export/import and purchase of spinning reserve is also illustrated. >

Risk constrained economic load dispatch in interconnected generating systems

A risk-constrained unit loading technique for interconnected systems is presented which utilizes a least-costly deviation for economic load dispatch to satisfy the risk criteria. The technique is developed on the basis of each area in a multi-area configuration fulfilling one of two different response risk criteria. The technique is illustrated with numerical examples. Risk-constrained economic loading schedules have been developed using reloading steps of 1 MW and 5 MW. In an actual system, other reloading steps should be tried in order to meet the specific needs of the system in terms of operating economy and computation time. >