Mircea Dobriceanu

Considerations regarding dynamic regimes of reluctance synchronous motors

A Matlab-Simulink model for the reluctance synchronous motor is presented in this paper. The synchronous machine equations written in the two axes theory are the starting point. A series of simulations emphasizing some parameters effects on the motor behaviour in dynamic regime have been carried out with the help of this model. A test bench for reluctance synchronous motors is presented further on. The connection schemes corresponding to the steady state and dynamic regimes are detailed. The acquisition program, specially designed and conceived, is also presented. The paper closes with a few suggestive experimental results and conclusions.

DC-bus voltage optimum control of three-phase shunt active filter system

The aim of this paper is to identify an optimum control strategy of three-phase shunt active filters to minimize the total harmonic distortion factor of the supply current. Some design aspects starting from power that must be compensated are taken into consideration. The DC-bus capacitor operation has been simulated using Matlab-Simulink environment and the results are very interesting. It is shown that there is an optimum value of the DC-bus voltage which minimizes the supply current harmonic distortion factor. It corresponds to the equality between apparent powers at the AC and DC-sides of the active power filter. Finally, predicted results are verified by experimental way on a MaxSine active power filter.

Analysis and optimal design of matching inductance for induction heating system with voltage inverter

This paper investigates the effects of the matching inductance on the quality of the power transfer in the induction heating system with voltage inverter and parallel resonance. Two analyzing methods are used for the matching inductance effect on the current through the inverter and the current through the equivalent inductor. It is shown that there is an optimal value of the matching inductance that maximizes the fundamental harmonic of the inverter and inductor currents and minimizes the third-order harmonic.

On the cascade control system tuning for shunt active filters based on modulus optimum criterion

This paper focuses on the control system for the output current and voltage across the DC capacitor of a three-phase shunt active filter. A classical PI-PI cascade control solution is taken into consideration. The design of both inner current loop and outer voltage loop is based on Modulus– Optimum criterion. It is pointed out that this tuning approach provides a good phase margin. In order to finalize the voltage controller tuning, the passband of the unity feedback system is imposed. Simulations were performed under Matlab-Simulink environment and the results are presented to show the effectiveness of such tuning technique. Moreover, the experimental results agree with the simulated waveforms of the current supply.

Considerations Regarding Determination of the Induction Motors Parameters

In this paper there is presented a new method for the determination of the induction machine parameters with the help of the data acquired in the no-load starting case. Is detailed the computation method, grounded with the help of the mathematical model in the two axes theory and of the optimisation algorithm SIMPLEX, the connexion schema, the experimental results and the conclusions.

Automated Data Acquisition System for Monitoring Electrical Stations

In an efficient process drive, the monitoring function is absolutely necessary because decision can be taken only based on correct and complete information about the parameters which characterize the process. An example of a process which requires such a monitoring is represented by the one associated to a electrical energy flow supervision system, which has the purpose of monitoring and storing the electrical parameters which are taken from the electrical stations. In this way, it is presented an data acquisition equipment which is incorporated in a dispatching system aiming the monitoring and storing of electrical parameters which are taken from electrical cells which compose the supervised electrical station. The use of the equipment will allow permanent monitoring of electrical stations functioning and storing of events or flaws which can appear in the functioning process

Method and system for monitoring the power quality in electrical distribution stations

The quality of the electrical energy becomes more and more one of the important parameters in the providers offer to consumers and often the decisional factor in choosing a provider from the electrical energy market. This constraints the functioning of all the receivers at normal parameters, deviations from a prescribed limit leading to an impossible functionality, damages and/or failure of these. Under these circumstances in the last years the problem became more important, being the subject of different studies at international level, which lead to the introduction of new norms and standards regarding the parameters for providing the electrical energy. The problem that rises is regarding the monitoring of these parameters, of the way in which it is verified that the imposed conditions are respected, and also the building of dedicated equipments. In this way the paper presents a monitoring system formed of local data acquisition, command and control equipments mounted at the level of each cell within the electrical distribution stations. These equipments are connected to a central dispatcher, which processes the information received and which runs dedicated software in order to assure functions for monitoring, diagnosis and analysis.

Improvement of power quality and energy efficiency in bucharest metro traction substations

This paper focuses on the analysis of the power quality and energy efficiency in the Bucharests subway traction substations and finding solutions for their improvement. Two directions are taken into consideration. The former consists in the active filtering of the current and the reactive power compensation, so that the traction substations to operate in conditions of unity power factor. The latter relates to the recovery of the energy available in the regenerative braking process. The conducted analysis and the proposed technical solution take into account the concrete structure of the traction substations and the existing Bombardier trains, which constitutes the most of the current park in operation. The performance of the proposed filtering and regeneration system is determined based on a complex Simulink model and confirms the validity and the efficiency of the proposed solution.

Orthogonal reference frame based methods in three-wire active power line conditioners: Practical evaluation under unbalanced load and nonideal voltage conditions

This paper is concerned with the practical implementation of some orthogonal reference frame based methods in the control of a shunt three-phase three wire active power line conditioner in order to compensate unbalanced nonlinear loads under nonideal voltage conditions. The first two developments are based on the components of voltage and current space vectors in the orthogonal stationary reference frame associated with the p-q theory of the instantaneous reactive power. They allow obtaining either unity power factor or perfect harmonic cancellation after compensation. Other two developments are based on the current components in the orthogonal rotating reference frame d-q with axis d in the direction of the voltage vector, which is specific of the id-iq method. This time, the compensation target is the total compensation through the perfect harmonic cancellation. The control algorithms were first modelized and tested by simulation under Matlab/Simulink. Then, experimental tests were conducted on a dSPACE platform based on DS1103 controller board for modern rapid prototyping. The compensating performance, in terms of harmonic distortion factor, unbalance factor, global power factor and displacement power factor, are analyzed for each situation. All the results prove that the desired compensation goals can be achieved through the conceived algorithms and the proposed practical implementation.

Electrical stations real-time monitoring using combined protection and control systems

The paper describes medium voltage electrical stations in which there is going to be implemented an automated monitoring system formed of local data acquisition, protection and control equipments mounted at the level of each cell within the electrical stations. This monitoring system is based on software packages for data acquisition, storing, data transmission and processing, monitoring and analysis. Tasks entailing the protection of operating plant, supervision of the system, detection and provision of measured values and messages for cases of operation, recording and evaluating measured values and messages for disturbances, control and locking functions as well as various possibilities of communication are to be mentioned here as being of great importance. In this way, the system is to help the human factor in taking optimal decisions in monitoring the electrical stations, by offering adequate information in a specific format. The internal modular set-up of hardware and software permits flexible inclusion of extensions and customers requirements according to needs.