Iranian Journal of Electrical and Electronic Engineering

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Because of temperature independence, high resolution and noiseless outputs, brushless resolvers are widely used in high precision control systems. In this paper, at first dynamic performance characteristics of brushless resolver, considering parameters identification are presented. Then a mathematical model based on d-q axis theory is given. This model can be used for studying the dynamic behavior of the resolver and steady state model is obtained by using dynamic model. The main object of this paper is to present an approach to identify electrical and mechanical parameters of a brushless resolver based on DC charge excitation and weight, pulley and belt method, respectively. Finally, the model of resolver based on the obtained parameters is simulated. Experimental results approve the validity of proposed method.

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A mathematical model based on d-q axis theory and dynamic performance characteristic of brushless resolvers is discussed in this paper. The impact of rotor eccentricity on the accuracy of position in precise applications is investigated. In particular, the model takes the stator currents of brushless resolver into account. The proposed model is used to compute the dynamic and steady state equivalent circuit of resolvers. Finally, simulation results are presented. The validity and usefulness of the proposed method are thoroughly verified with experiments.

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In this paper we present a general formalism for the establishment of the family of selective partial update affine projection algorithms (SPU-APA). The SPU-APA, the SPU regularized APA (SPU-R-APA), the SPU partial rank algorithm (SPU-PRA), the SPU binormalized data reusing least mean squares (SPU-BNDR-LMS), and the SPU normalized LMS with orthogonal correction factors (SPU-NLMS-OCF) algorithms are established by this general formalism. In these algorithms, the filter coefficients are partially updated rather than the entire filter coefficients at every iteration which is computationally efficient. Following this, the transient and steady-state performance analysis of this family of adaptive filter algorithms are studied. This analysis is based on energy conservation arguments and does not need to assume a Gaussian or white distribution for the regressors. We demonstrate the performance of the presented algorithms through simulations in system identification and acoustic echo cancellation scenarios. The good agreement between theoretically predicted and actually observed performances is also demonstrated

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Robust performance controller design for duty-cycle controlled series resonant converter (SRC) is proposed in this paper. The uncertainties of the converter are analyzed with load variation and power circuit components tolerances are taken into consideration. Additionally, a nominal performance (NP) controller is designed. Closed-loop system is simulated with Orcad and simulation results of robust controller are compared with nominal performance controller. Although nominal performance controller has better performance for nominal plant, the robust performance controller is advantageous in dealing with uncertainties.

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The recent trends in electrical power distribution system operation and management are aimed at improving system conditions in order to render good service to the customer. The reforms in distribution sector have given major scope for employment of distributed generation (DG) resources which will boost the system performance. This paper proposes a heuristic technique for allocation of distribution generation source in a distribution system. The allocation is determined based on overall improvement in network performance parameters like reduction in system losses, improvement in voltage stability, improvement in voltage profile. The proposed Network Performance Enhancement Index (NPEI) along with the heuristic rules facilitate determination of feasible location and corresponding capacity of DG source. The developed approach is tested with different test systems to ascertain its effectiveness.

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Deregulation of power system in recent years has changed static security assessment to the major concerns for which fast and accurate evaluation methodology is needed. Contingencies related to voltage violations and power line overloading have been responsible for power system collapse. This paper presents an enhanced radial basis function neural network (RBFNN) approach for on-line ranking of the contingencies expected to cause steady state bus voltage and power flow violations. Hidden layer units (neurons) have been selected with the growing and pruning algorithm which has the superiority of being able to choose optimal unit’s center and width (radius). A feature preference technique-based class separability index and correlation coefficient has been employed to identify the relevant inputs for the neural network. The advantages of this method are simplicity of algorithm and high accuracy in classification. The effectiveness of the proposed approach has been demonstrated on IEEE 14-bus power system.

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In this paper, the performance of the EGLA (Externally Gaped Line Arresters) and its impact on the back flashover rate of a 400 kV transmission line have been investigated. The frequency behavior of the grounding system and soil resistivity has been modeled. To analyze the EGLA performance in relation to the grounding system's frequency behavior, a rod-shaped grounding system model has been implemented. By placing the EGLA at different phases of the transmission line, the best scenario has been identified to minimize back-flashover occurrences. Furthermore, the performance of the frequency grounding system to that of the nonlinear grounding system has been compared. The results clearly indicate that using a nonlinear grounding system leads to higher back flashover rates compared to the frequency grounding system. Additionally, the EGLA absorbs less energy when connected to a nonlinear resistor compared to the frequency grounding system. It can be concluded that modeling the grounding system's frequency behavior using the frequency grounding model provides more accurate results, especially in investigations related to power grid insulation coordination.

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The scaling limitations of Complementary Metal-Oxide-Semiconductor (CMOS) transistors to achieve better performance have led to the attention of other structures to improve circuit performance. One of these structures is multi-valued circuits. In this paper, we will first study Carbon Nanotube Transistors (CNT). CNT transistors offer a viable means to implement multi-valued logic due to their variable and controllable threshold voltage. Subsequently, we delve into the realm of three-valued flip-flop circuits, which find extensive utility in digital electronics. Leveraging the insights gained from our analysis, we propose a novel D-type flip-flop structure. The presented structure boasts a remarkably low power consumption, showcasing a reduction exceeding 61% compared to other existing structures. Furthermore, the proposed circuit incorporates a reduced number of transistors, resulting in a reduced footprint. Importantly, this circuit exhibits negligible static power consumption in generating intermediate values, rendering it robust against process variations.  Overall, the proposed circuits demonstrate a 29.7% increase in delay compared to the compared structures. However, they showcase a 96.1% reduction in power-delay product (PDP) compared to the other structures. The number of transistors is also 8.3% less than other structures. Additionally, their figure of merits (FOM) are 19.7% better than the best-compared circuit, underscoring its advantages in power efficiency, chip area, and performance.

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Low inertia is one of the most important challenges for frequency maintenance in islanded microgrids. To address this issue, the innovative concept of Virtual Inertia Control (VIC) has emerged as a promising solution for enhancing frequency stability in such systems. This paper presents an advanced controller, the PD-FOPID, as a highly effective technique for improving the efficiency of VIC in islanded microgrids. By leveraging the Rain Optimization Algorithm (ROA), this approach enables precise fine-tuning of the controller's parameters. A key advantage of the proposed method is its inherent resilience to disruptions and uncertainties caused by parameter fluctuations in islanded microgrids. To evaluate its performance and compare it with alternative control methods, extensive assessments were conducted across various scenarios. The comparison includes VIC based on an H-infinity controller (Controller 1), VIC based on an MPC controller (Controller 2), Adaptive VIC (Controller 3), VIC based on an optimized PI controller (Controller 4), conventional VIC (Controller 5), and systems without VIC (Controller 6). The results demonstrate that the proposed methodology significantly outperforms existing approaches in the field of VIC. The simulations were conducted using MATLAB software.