Study of resonances in 1 x 25 kV AC traction systems with external balancing equipment

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.AC traction systems are 1 × 25 or 2 × 25 kV/50 Hz single-phase, nonlinear, time-varying loads that can cause power-quality problems, such as unbalanced or distorted voltages. To reduce unbalance, external balancing equipment is usually connected to these systems, forming the Steinmetz circuit. Parallel resonances can occur in these types of circuits, exciting the harmonic emissions (below 2 kHz) of railway-adjustable speed drives. This paper studies these resonances at pantograph terminals and provides analytical expressions to determine their harmonic frequencies. The expressions are validated from several traction systems in the literature and PSCAD simulations.Postprint (author's final draft

Direct power control of shunt active filter using high selectivity filter (HSF) under distorted or unbalanced conditions

International audienceThis paper describes the design of a new configuration of direct power control (DPC) based on high selec-tivity filters (HSF) to achieve near-sinusoidal source current waveforms under different source voltageconditions. The proposed method uses the high selectivity filters instead of the classical extraction filters(low pass filters). The basic idea of the proposed DPC is to choose the best inverter voltage vector in orderto minimize instantaneous active and reactive power errors using two hysteresis comparators. Their out-puts associated with a switching table, control the active and reactive powers by selecting the optimalswitching states of the inverter. Simulation results have proved excellent performance, and verify thevalidity of the proposed DPC scheme, which is much better than conventional DPC using low pass filters

LED lamp modelling for harmonic studies in distribution systems

Energy saving policies have boosted the use of light emitting diode (LED) lamps in distribution networks. These lamps are non-linear loads which inject harmonic currents into the distribution system, which has led to a decrease in the system power quality. Study of the modelling of these lamps would allow the prediction of harmonic emissions into distribution systems. This study presents a frequency-domain LED lamp model for harmonic emission calculation, together with a simple estimation procedure for model parameter determination from experimental measurements. Both were validated by laboratory tests. Finally, an application illustrates the effect of widespread use of LED lamps in a typical distribution system and allows LED lamp models to be compared.Postprint (author's final draft

LED lamp modelling for harmonic studies in distribution systems

Energy saving policies have boosted the use of light emitting diode (LED) lamps in distribution networks. These lamps are non-linear loads which inject harmonic currents into the distribution system, which has led to a decrease in the system power quality. Study of the modelling of these lamps would allow the prediction of harmonic emissions into distribution systems. This study presents a frequency-domain LED lamp model for harmonic emission calculation, together with a simple estimation procedure for model parameter determination from experimental measurements. Both were validated by laboratory tests. Finally, an application illustrates the effect of widespread use of LED lamps in a typical distribution system and allows LED lamp models to be compared

An Improved Mutated Predictive Control for Two-Level Voltage Source Inverter With Reduced Switching Losses

This paper presents an approach called the mutated model predictive control strategy to reduce switching losses and enhance the efficiency of voltage source inverter (VSI) operating with a three-phase configuration. The high number of semiconductor commutations in VSIs can lead to significant switching losses, which reduces efficiency and requires large heat sinks. Conventional model predictive control (MPC) applies switching states directly to the VSI without modulation; the selection of the optimal state is accomplished by evaluating criterion. However, since the two zero vectors (V0, V7) generate identical output voltage vectors(VVs), only a single zero voltage vector can be chosen. In contrast, the proposed method uses both zero vectors based on the operating condition. The approach involves using a switching strategy with pre-condition to select the suitable zero vector between (V0, V7) and apply it for the next sampling period. The efficacy of the proposed approach is validated by conducting simulations utilizing Matlab/Simulink and PLECS software, as well as an experimental test setup is utilized, which includes a three-phase VSI connected to a resistive-inductive load. The VSI is controlled using a dSPACE MicroLabBOX. The results clearly demonstrate the superiority of the proposed control strategy, specifically in terms of reducing switching losses and improving the efficiency of the VSI

Model-Free Predictive Current Controller for Voltage Source Inverters Using ARX Model and Recursive Least Squares

This brief proposes a model-free deadbeat predictive controller (MF-DPC) for voltage source inverters. The proposed control scheme does not require knowledge of the system parameters for its correct operation. This is performed using an auto-regressive with exogenous input (ARX) model with a recursive least squares (RLS) estimation algorithm for parameter identification to represent the physical system. A state-space predictive model using the identified parameters and the past data measurements is established to calculate the inverter voltage reference using the deadbeat control principle and generate it using space vector modulation (SVM) allowing fixed-switching operation. In addition, the inherent sensitivity of the deadbeat controller to parameter mismatches is avoided. Simulation and experimental results confirm the validity of the proposed model-free control approach in terms of tracking accuracy and waveform quality.</p

An Improved Mutated Predictive Control for Two-Level Voltage Source Inverter With Reduced Switching Losses

This paper presents an approach called the mutated model predictive control strategy to reduce switching losses and enhance the efficiency of voltage source inverter (VSI) operating with a three-phase configuration. The high number of semiconductor commutations in VSIs can lead to significant switching losses, which reduces efficiency and requires large heat sinks. Conventional model predictive control (MPC) applies switching states directly to the VSI without modulation; the selection of the optimal state is accomplished by evaluating criterion. However, since the two zero vectors (V0, V7) generate identical output voltage vectors(VVs), only a single zero voltage vector can be chosen. In contrast, the proposed method uses both zero vectors based on the operating condition. The approach involves using a switching strategy with pre-condition to select the suitable zero vector between (V0, V7) and apply it for the next sampling period. The efficacy of the proposed approach is validated by conducting simulations utilizing Matlab/Simulink and PLECS software, as well as an experimental test setup is utilized, which includes a three-phase VSI connected to a resistive-inductive load. The VSI is controlled using a dSPACE MicroLabBOX. The results clearly demonstrate the superiority of the proposed control strategy, specifically in terms of reducing switching losses and improving the efficiency of the VSI