Showing papers by "Hermann W. Dommel published in 1998"
18 Aug 1998
TL;DR: This paper presents the solution approach and implementation strategy followed in the development of the OVNI ("Object Virtual Network Integrator") power system simulator, and implements the MATE concept ("multi-area tearing equivalent") for network partitioning.
Abstract: This paper presents the solution approach and implementation strategy followed in the development of the OVNI ("Object Virtual Network Integrator") power system simulator. OVNI's aim is to represent full-size power system networks for real-time and online simulation. To cope with the dimensions of the problem, partitioning techniques are required, both in the system solution and in the hardware implementation. OVNI implements the MATE concept ("multi-area tearing equivalent") for network partitioning. In addition to the considerable solution speedups that can be achieved, the MATE concept is particularly suited for software implementation using object-oriented techniques and for hardware implementation using parallel processing schemes.
58 citations
14 Oct 1998
TL;DR: It appears that fuzzy set theory can play an important role in diagnosing power quality disturbances, and hence it can offer insights towards the satisfaction of the needs of manufacturers, utilities and customers.
Abstract: This paper presents a case study application of fuzzy logic in a power quality issue. It describes the computer-based load sensitivity to voltage sags, by using fuzzy sets and IF-THEN inference rules. The load sensitivity is based on the steady-state and transient voltage versus time profile according to the IEEE Std. 446, also referred to as the CBEMA (Computer Based Equipment Manufacturer Association) curve. Fuzzy logic allows the modeling of the inherent uncertainty of the load reliability. This expresses how the success or failure of computer based loads is correlated with short term voltage variations in the electric supply system. A fuzzy inference system is experimentally implemented for these cases, showing the general procedures of how to use this theory. It appears that fuzzy set theory can play an important role in diagnosing power quality disturbances, and hence it can offer insights towards the satisfaction of the needs of manufacturers, utilities and customers.
27 citations
18 Aug 1998
TL;DR: In this paper, a generalized method for three-phase power flow analysis is developed using the concept of component level power flow constraints, and case studies supported by field measurement results are used to verify the proposed method and to demonstrate the deficiencies of traditional methods.
Abstract: Phase voltage and current unbalance is a basic power quality concern. Three-phase power flow analysis is needed to investigate unbalance problems. In this paper, the unique modelling issues associated with unbalanced power flow calculations are discussed. Four types of load models are proposed. Using the concept of component level power flow constraints, a generalized method for three-phase power flow analysis is developed. Case studies supported by field measurement results are used to verify the proposed method and to demonstrate the deficiencies of traditional methods.
20 citations
24 May 1998
TL;DR: An intelligent system to support EMTP simulation is introduced and the simulation results show that the fuzzy logic is suitable to evaluate the results of EMTP.
Abstract: The Electromagnetic Transients Program (EMTP) is a general purpose computer program for simulating fast transient effects in electric power systems. The application of the EMTP is not easy, because it requires highly specialized expertise. This paper introduces an intelligent system to support EMTP simulation. This intelligent system works in three steps. Initially, the support system selects a base case, from a case data base to be modified to meet the user's requirement. Then, the expert system checks the syntax and validity of the new case data. Finally, the EMTP solution is checked whether it is reasonable. The results evaluation of the EMTP solution is presented in more detail using fuzzy logic. The EMTP expert knowledge is expressed by fuzzy sets in order to check the time domain solution of the EMTP. The simulation results show that the fuzzy logic is suitable to evaluate the results of EMTP.
4 citations
14 Oct 1998
TL;DR: In this paper, a simple procedure to reduce the error effects without increasing computation time is proposed. But the procedure is not suitable for the case of strong resonances. And it may not be applicable to all cases of strong resonance.
Abstract: EMTP errors in the electrical power system impedance representation may not be negligible in the presence of strong resonances. This aspect is analysed with reference to harmonic distortion analysis and a simple procedure, which reduces the error effects without increasing computation time, is suggested.
3 citations