Existing conditions in industrial ac-dc power systems may result in significant commutation resistances. If the resistance to reactance ratio of the commutation impedance is high, significant errors ...can result in load-flow studies which neglect the resistive portion. A method is presented for inclusion of a resistance-inductance fed bridge rectifier in a Newton-Raphson (N-R) load flow program. Polar form of the power flow equations is assumed. An example problem is provided for comparison.
Equations describing the ac-dc terminal relationships of the resistance-inductance-fed three-phase full-wave bridge converter from no load to short circuit are provided. Modal boundaries are plotted ...in the µ-α plane showing the limits within which these equations are valid. Results show the resistance to have a significant effect on the terminal characteristics. Modal boundaries are shown to be nonlinear functions of the commutation resistance-direct current product.
The absence of harmonic filters at the terminals of bridge rectifiers in an industrial ac-dc power system causes part of the system impedance to become part of the commutation impedance. If the ...resistance to reactance ratio of the commutation impedance is high, significant errors can result in load flow studies which neglect the resistive portion. A method is presented for inclusion of a resistance-inductance fed bridge rectifier in a Newton-Raphson load flow program. Polar form of the power flow equations is assumed. An example problem is provided for comparison.
Equations are derived which describe the terminal behavior of the uncontrolled resistance-inductance fed bridge converter. Generalization of these equations to the controlled case is accomplished by ...a substitution of variables. Boundaries within which the uncontrolled rectifier can operate are specified. Plots of the terminal characteristics for the uncontrolled case visually show the approximation involved when the resistive portion of the commutation impedance is neglected, A simple approximation is provided for the fundamental current component eauations which are derived.
Mine electrical power-flow solutions are often obtained using personal computers. Because of the limited precision used by the compilers on these machines, power-flow solution procedures may diverge ...or possibly oscillate until the iteration limit is reached, even though an operable solution exists. Two methods to create virtually extended-precision calculations in full Newton-Raphson and decoupled powerflow algorithms without the attendant slow down associated with full double-precision codes are presented. It is shown that insufficient precision for convergence of the IEEE 118 bus system occurs near the single precision limit of a PC- or VAX-class minicomputer, the number of bits required for convergence can be simply and quickly estimated and the most critical routine in which precision generally needs to be increased is the mismatch routine. Simulation results are discussed.< >
