M. Gray

Power Quality Assessment in Distribution Systems Embedded With Plug-In Hybrid and Battery Electric Vehicles

The impact of electric vehicles on power quality in electric distribution system is evaluated. Voltage deviations such as under/over voltage and voltage imbalance are probabilistically quantified using Monte Carlo. Moreover, distribution transformers overload and unbalance are assessed for different vehicle types (i.e., plug-in hybrid and battery electric), different vehicle penetration (up to 50%) while considering level 1 and level 2 charging. The results of Monte Carlo reveal that battery electric vehicles can cause more overload to distribution transformers compared to plug-in hybrid electric vehicles. Also level 2 and level 1 can be problematic resulting in secondary bus undervoltage and transformer unbalance, respectively.

Application of wavelet-based classification in non-intrusive load monitoring

In this paper, non-intrusive load monitoring using a single point sensing and wavelet-based classification is presented and applied to a test system feeding two dynamic and two static three-phase loads. The features in the three-phase voltage and current signals are extracted by wavelet transform to decompose the original signals. The energy of the obtained wavelet coefficients at the detail levels constitute a feature set for classification. Decision trees representing ensemble classifiers are then developed using the wavelet-based features and the performance of each ensemble classifier is then evaluated in the presence of several power quality disturbances resulting from applying several faults types and at different locations. The results have shown that higher order Daubechies wavelets, and in particular Daubechies of order 5, as well as more decision trees in the ensemble classifier both contribute to more accurate classification.

Application of Directed Bacterial Foraging Optimization for voltage collapse detection

This paper presents a hybrid optimization methodology based on directing the foraging of E-Coli bacteria to address the problem of voltage collapse (VC) in electric power systems (EPS). The proposed methodology, named Directed Bacterial Foraging Optimization (DBFO) is described, the results are presented and conclusions are drawn.

Multi-objective optimization of energy storage and wind DGs for self-adequacy of microgrid equipped with fast DC charging station

This paper presents a framework to determine the optimal siting and sizing of Wind-based distributed generators (WDGs) and energy storage systems (ESSs) in a micro-grid (MG), considering the total active power losses in the system, the self-adequacy index (SAI), and the total annual cost (TAC) of the WDGs and the ESSs. The work in this paper employs multi-objective optimization (MOO) based on archived multi-objective simulated annealing in order to obtain a diverse set of Pareto optimal solutions. The analysis formulates the siting and sizing optimization problem considering a MG with a Fast Direct Current Charging Station (FDCCS). The results of the simulation have revealed that the optimal solution results in a trade-off between increasing SAI and increased TAC. Finally, it was seen that the optimal siting and sizing of the WDGs are highly affected by the location of the FDCCS.

Low and high order harmonic emission quantification of plug-in hybrid and battery electric vehicles

This paper quantifies the harmonic emissions from plug-in hybrid electric vehicles and battery electric vehicles considering indoor level 1 and outdoor level 2 charging. Harmonic distortion trends along the charging period and the harmonic groups and inter-harmonic groups for three electric vehicles (plug-in hybrid sedan, battery electric hatchback and electric pick-up truck) are assessed from harmonic emission point of view. The results revealed that the harmonic distortion level varies depending on the charging level and the vehicle type. Moreover, the current harmonic distortion becomes of time-varying characteristics near the end of the charging period before the battery becomes fully charged. Also for both charging levels, the 95th percentile of the harmonic groups decreases at high order harmonics while the opposite is true in case of inter-harmonic groups.

Time-varying power quality in unbalanced three-phase systems

This paper investigates the effectiveness of implementing the un-decimated wavelet transform (UWT) in the computation of reactive power in three-phase system subject to time-varying disturbance. The advantages of this decimation-free wavelet transform are highlighted and the formulation of the reactive power in the un-decimated wavelet domain is presented based on two reactive power metering approaches namely; 1) “non-quadrature” and 2) “quadrature” approaches. Various case studies including different loading conditions and/or time-variant/time-invariant disturbances are presented to exemplify the effectiveness of using the un-decimated wavelet in the reactive power measurement in both balanced and unbalanced three-phase systems. The results of the analysis are compared to the reactive power values based on the decimated wavelet transform (DWT) and conclusions are presented.

Application of PSO and fuzzy logic for underfrequency load shedding

Islanded operation of power systems with a shortage of generation to meet the local demand may experience a dip in frequency which could potentially damage the system equipment unless proper action is taken to shed loads in a timely manner. Recent research has shown that the uncertainty associated with estimating the amount of load to be shed can be better handled by fuzzy systems; however, there is not much work on determining the optimal settings of the fuzzy system parameters. This paper presents the application of Particle Swarm Optimization (PSO) in optimization of a fuzzy system used in underfrequency load shedding (UFLS).