A New and Accurate Modeling Technique for Glass Resistance in Multiphase Multielectrode Glass Furnaces

One of the design elements involved in sizing the electrical power equipment for glass furnaces is the determination of the glass resistances between the operating electrodes. All methods used for this purpose to date are approximate and are based on a simple model considering the resistance between only two electrodes at the time. This paper presents a technique to develop a resistance model for any general configuration of electrodes and supply voltages in glass furnaces. The technique is based on relating the glass conductivity as represented by Ohm's law to the electrostatic property as represented by Gauss's law. The resistance model is then derived in a matrix form using the bus admittance frame of reference. A digital computer program has been developed to implement the proposed technique and example results are presented.     

A model to predict current distributions in bundled cables forelectric glass melters

A model for predicting the current distribution in high-current cables that are constructed from bundles of parallel conductors (strands) is presented. These cables are typically used in electric glass melters to interconnect the power transformers and the melter secondary bus installations. Due to the phenomenon known as the skin effect, the magnetic field forces inside the bundled cable will tend to drive the current toward the outermost strands. The proposed model is developed by starting from the fundamentals of the skin effect phenomenon for solid conductors and then extending the concept for bundled cables. The model has also been coded in a simple FORTRAN computer program. Results obtained using the proposed model for a variety of cable bundling configurations are presented for demonstration purposes. These results show that currents in the outermost layers of bundled cables can exceed those of the innermost layers by a factor of four or more, depending on the total cable size     

Accurate modeling of interelectrode resistance and powerdissipation in electric glass melters

An accurate technique for modeling the interelectrode resistances as well as the potential and power density distributions in electric glass melters is presented. The model also provides necessary data for sizing the supply transformers associated with such melters. The solution technique involves only algebraic equations, and therefore can be implemented by simple computer software. An example melter with a two-phase supply and eight electrodes was simulated using the proposed three-dimensional modeling technique. Because of the general nature of the proposed model, this technique provides a valuable as well as reliable and easily implemented design tool for melters with multiphase power supplies and general electrode configurations     

Design of a model reference adaptive stabilizer for the exciter andgovernor loops of power generators

The authors present a decentralized model reference adaptive control (DMRAC) scheme for the design of power system stabilizers (PSS) and a means for coordinating the generating unit excitation and governor control loops. In the excitation and governor control loops. In the proposed scheme, the state variables of the generating unit (GU) are to track those of an explicitly specified reference system which is designed to have desirable performance characteristics. The adaptive control law for coordinating the exciter-governor stabilizer signals is derived from a Lyapunov energy function, and thus assures system stability. Decentralized regulation and tracking tests on simulated one-machine infinite bus system show significant improvement in system performance