Classical Machine Model Research Articles

Investigation on the Effects of Magnetic Saturation in Six-Phase Induction Machines with and without Cross Saturation of the Main Flux Path

The operational characteristics during transients are significantly influenced by magnetic saturation in electrical equipment. For the computation of steady-state rated operation in multiphase induction machines, the assumption of linear magnetic behavior of the iron core in classical machine models may be sufficient. The mathematical models of the considered models differ in terms of the existence or absence of dynamic cross-saturation effects. The approach that is most frequently used to examine the impact of magnetic saturation is based on the state-space variable representation of the mathematical model in dynamic axes (d–q). The purpose of this research is to investigate the effects of magnetic saturation on six-phase induction machines. In this study, a d–q transformation-based model of a six-phase induction machine (SPIM), including the magnetic saturation effect, is developed. The cross-saturation and the common mutual leakage inductance between the two sets of stators’ windings are then developed and analyzed, and the developed models were simulated and results are compared with and without cross-saturation. The main and leakage flux saturation, as well as the mutual coupling between the two windings, are all accounted for in the model, which is based on the vector space decomposition method. A significant increase in currents and voltage results from the highly saturated magnetic paths of the leakage fluxes in six-phase induction machines. In order to investigate the impact of cross-saturation, inductances computed using analytical methods and those without taking cross-saturation into consideration were compared. These outcomes are then transformed into a condensed current depending on parameter functions for transient machine models.

Performing fully parallel constraint logic programming on a quantum annealer

AbstractAquantum annealerexploits quantum effects to solve a particular type of optimization problem. The advantage of this specialized hardware is that it effectively considers all possible solutions in parallel, thereby potentially outperforming classical computing systems. However, despite quantum annealers having recently become commercially available, there are relatively few high-level programming models that target these devices. In this article, we show how to compile a subset of Prolog enhanced with support for constraint logic programming into a two-local Ising-model Hamiltonian suitable for execution on a quantum annealer. In particular, we describe the series of transformations one can apply to convert constraint logic programs expressed in Prolog into an executable form that bears virtually no resemblance to a classical machine model yet that evaluates the specified constraints in a fully parallel manner. We evaluate our efforts on a 1,095-qubit D-Wave 2X quantum annealer and describe the approach's associated capabilities and shortcomings.

Investigation on the Effects of Magnetic Saturation in Induction Machines During Transients

AbstractMagnetic saturation in electrical machines is of major influence on the operating characteristics during transients. For induction machines, the assumption of linear magnetic behavior of the iron core in classical machine models may be adequate for the calculation of steady-state rated operation. In operating points or during transients following a short-circuit or out-of-phase synchronization, where currents can reach values as high as 25 pu, especially the magnetic paths of the leakage fluxes are highly saturated, leading to a significant raise in currents and machine torque. Therefore an investigation on the effect of magnetic saturation has been performed by comparing inductances calculated by analytical methods for assumed linear magnetic behavior with results of static finite-element-method (FEM) models taking magnetic saturation into account. These results are subsequently converted into simplified current-depending parameter functions that can be used in transient machine models. Therefore, based on an enhanced space phasor approach, a newly modified machine model is presented, where the parameters can be used according to the dependencies worked out in the paper in order to identify deviations with the classical approach using constant inductances. Furthermore the newly acquired set of current-depending machine inductances is validated by simulating a series of transients using dynamic FEM calculation, showing a significant improvement in accuracy compared to sets of constant parameters.

Transient Stability Constrained Line-Flow-Based Optimal Power Flow Analysis

This paper establishes a new method that adopts the line-flow-based (LFB) approach to develop a transient stability constrained optimal power flow (OPF) analysis called LFB-TSCOPF. The transient energy function (TEF) serves as a direct means of carrying out the stability analysis. The reduction technique was adopted in which the classical machine model was reduced to the internal node model. The proposed method was tested on the WECC 9-bus, three-machine, IEEE 14-bus, five-machine, and the New England 39-bus, ten-machine test systems. The results were compared with other known results from different methods in literature. The results of the active power and total optimal costs are quite promising and consistent with other known methods. The LFB-TSCOPF re-dispatches real power by applying the energy margin performance index as an indication of the generator unit(s) to be rescheduled. The LFB-TSCOPF provides a more comprehensive linear model, reduces computation time and can be useful for online stability studies.

Application of robust control to sustained oscillations in power systems

Transient control of the sustained oscillations that can occur after a major disturbance to a power system is investigated. A control scheme for an n-generator system is first developed using a classical machine model, and then extended to a machine model that includes governor/turbine dynamics. The proposed control strategies are linear and require only local relative angle and velocity measurements for the classical model case, plus the measurement of mechanical power if governor/turbine dynamics are included. Using Lyapunov's direct method, the control is shown to be robust with respect to parameter and load variations, and topology changes in the power system. The overall power system is shown to be exponentially stable in the main so that any oscillation, anywhere in the system, can be damped efficiently. The results are obtained without any linearization of the power system model. Simulation results for the 30-bus New England system demonstrate the effectiveness of the proposed control. >