Damian Vilchis-Rodriguez

Estimation of Composite Load Model Parameters Using an Improved Particle Swarm Optimization Method

Power system loads are one of the crucial elements of modern power systems and, as such, must be properly modelled in stability studies. However, the static and dynamic characteristics of a load are commonly unknown, extremely nonlinear, and are usually time varying. Consequently, a measurement-based approach for determining the load characteristics would offer a significant advantage since it could update the parameters of load models directly from the available system measurements. For this purpose and in order to accurately determine load model parameters, a suitable parameter estimation method must be applied. The conventional approach to this problem favors the use of standard nonlinear estimators or artificial intelligence (AI)-based methods. In this paper, a new solution for determining the unknown load model parameters is proposed-an improved particle swarm optimization (IPSO) method. The proposed method is an AI-type technique similar to the commonly used genetic algorithms (GAs) and is shown to provide a promising alternative. This paper presents a performance comparison of IPSO and GA using computer simulations and measured data obtained from realistic laboratory experiments.

Supply Induced Interharmonic Effects in Wound Rotor and Doubly-Fed Induction Generators

This paper investigates the spectral effects that stator supply harmonics can induce in wound rotor and doubly-fed induction generators. The purpose of this study is to clarify the nature and the origin of the reported significant inter harmonic effects in these machines. To this end, the authors derive analytical expressions that define the spectral signature frequencies of individual supply harmonics in the current and torque signals. The expressions are first validated through comparison with the spectra calculated using a harmonic time-stepped machine model and then by spectral measurements on a laboratory test rig comprising a 30 kW machine excited by a programmable power supply unit. It is shown that the presence of supply harmonics can result in multiple and variable wide-band interharmonic effects in the current and torque signals. Finally, the interharmonic current emissions for the wound rotor and the doubly-fed mode of operation are experimentally quantified using the relevant IEC standard indices.

Investigation of induction generator wide band vibration monitoring using fibre Bragg grating accelerometers

This paper investigates the use of fibre Bragg grating (FBG) accelerometers for wide band vibration monitoring in wound rotor induction generators. The sensor performance is assessed in a series of experiments on a laboratory test rig comprising a 30 kW induction machine operating in healthy conditions and with electrical or mechanical fault. Vibration measurements are processed and analyzed in the frequency domain for fault feature extraction. The fibre optic sensor effectiveness in measurement of wide band fault signatures in the vibration signal is compared with that of a commercial piezoelectric based solution. The potential and limitations of the investigated FBG accelerometer design are evaluated for use in condition monitoring applications.

A review of technologies for MVDC circuit breakers

Medium voltage direct current (MVDC) distribution networks have been considered for various applications, such as offshore wind farm collector systems, all-electric naval vessels, and aircraft. MVDC circuit breakers are a critical technology to directly manage faults in multi-terminal DC (MTDC) networks. However, DC current breaking is much more challenging than in AC systems because there is no natural zero-crossing of the current waveform to aid fault isolation. This paper reviews existing MVDC circuit breaker technologies and also discusses their advantages and disadvantages. This paper also introduces new topologies that can be applied in MVDC applications. The operation of several hybrid DC circuit breaker topologies with aided commutation is included. The paper illustrates that a hybrid DC circuit breaker with aided commutation can clear a fault within 2-5 msecs with low losses, this shows great potential for future MVDC applications. The implications for the practical design of commercial MVDC circuit breakers are also discussed.

Wide band fiber Bragg grating accelerometer for rotating AC machinery condition monitoring

This paper investigates the use of fiber Bragg grating (FBG) accelerometers for wide band vibration monitoring in a wound rotor induction generator. The sensor performance is assessed in a series of experiments on a laboratory test rig comprising a 30kW induction machine operating under steady state and variable speed regimes. Vibration measurements are investigated in the frequency domain for generator fault specific electromagnetically induced vibration components. The fiber optic sensor effectiveness in detection of wide band spectral effects (<1kHz) in the vibration signal is compared with that of a commercial piezoelectric based solution. The potential and limitations of the prototype wide band FBG accelerometer are evaluated for use in vibration monitoring applications.

Finite element assessment of moving coil actuator for HVDC breaker applications

This paper assesses the suitability of the moving coil actuator for use as an ultra-fast, long stroke linear drive for HVDC breaker applications. With the help of FEA, a sensitivity analysis of the actuator is conducted in order to better understand how the different design parameters affect the actuator performance. Based on this assessment a high performance actuator design has been implemented using FEA software. Simulation results show the suitability of the moving coil design as an ultra-fast linear driver. Efficiency of the proposed moving-coil design has been calculated and shows a remarkable advantage over other high speed actuator designs.

Modelling Thomson Coils With Axis-Symmetric Problems: Practical Accuracy Considerations

This paper assesses factors that impact the simulation accuracy of a 2-D finite element (FE) transient axis-symmetric model of a Thomson coil (TC) actuator. Three-dimensional FE analysis (FEA) is used to show that geometric differences between a planar coil and the intrinsic assumptions of a 2-D axial model may result in important differences in coil inductance. It is then shown that inductance and resistance compensation of the 2-D model can be used to produce an accurate prediction of the TC performance. Detailed parameters of a prototype TC test system are used as inputs in the compensated 2-D axial model and excellent agreement is observed between 2-D FE simulations and experimental results. It is also shown that armature vibration modes explain the presence of apparent speed oscillations in the experimental results not present in numerical simulations. The compensated 2-D axis-symmetric model shows a good accuracy compared with experimental results for the investigated scenarios, even when an armature flexing is considered.

Modelling of induction machine time and space harmonic effects in the SIMULINK environment

High fidelity ac machinery models including harmonic effects are becoming increasingly desirable for use in improved fidelity machine and drive behavior analysis. This paper describes a method enabling the development of a dynamic induction machine model in SIMULINK which has a capability of representing time and space harmonic effects. The manuscript first presents the details of the model development and implementation. The proposed model performance is then validated through comparison with experimental current and torque signals data obtained from two separate induction machine laboratory test rigs. The results show a good agreement between measured and predicted data in the frequency domain and validate the competency of the presented model in representing harmonic effects.

Sensitivity assessment of wound rotor induction generator bearing fault detection using machine electrical quantities

This paper investigates the sensitivity of machine electrical quantities when employed as a means of bearing fault detection in wound rotor induction generators. Bearing failure is the most common failure mode in rotating AC machinery. With the widespread use of wound rotor induction machines in modern wind power generation, achieving effective detection of bearing faults in these machines is becoming increasingly important in order to minimize wind turbine maintenance related downtime. Current signature analysis has been demonstrated to be an effective technique for achieving detection of different fault types in ac machines. However, this technique lacks sensitivity when used for detection of bearing failures and therefore sophisticated post processing techniques have recently been suggested to improve its performance. As an alternative, this paper investigates the sensitivity of a range of machine electrical quantities to bearing faults, with the aim of examining the possibility of achieving improved bearing fault detection based on identifying a clear fault spectral signature. The reported signatures can be subjected potentially to refined processing techniques to further improve fault detection.Copyright