A review on data-driven fault severity assessment in rolling bearings

The coexistence of ac and dc subgrids in a hybrid microgrid is likely given that modern distributed sources can either be ac or dc. Linking these subgrids is a power converter, whose topology should preferably be not too unconventional. This is to avoid unnecessary compromises to reliability, simplicity, and industry relevance of the converter. The desired operating features of the hybrid microgrid can then be added through this interlinking converter. To demonstrate, an appropriate control scheme is now developed for controlling the interlinking converter. The objective is to keep the hybrid microgrid in autonomous operation with active power proportionally shared among its distributed sources. Power sharing here should depend only on the source ratings and not their placements within the hybrid microgrid. The proposed scheme can also be extended to include energy storage within the interlinking converter, as already proven in simulation and experiment. These findings have not been previously discussed in the literature, where existing schemes are mostly for an ac or a dc microgrid, but not both in coexistence.

Autonomous Control of Interlinking Converters with Energy Storages in Hybrid AC-DC Microgrids

Power systems are the most complex systems that have been created by men in history To operate such systems in a stable mode, several control loops are needed Voltage frequency plays a vital role in power systems which need to be properly controlled To this end, primary and secondary frequency control loops are used to control the frequency of the voltage in power systems Secondary frequency control, which is called Load Frequency Control (LFC), is responsible for maintaining the frequency in a desirable level after a disturbance Likewise, the power exchanges between different control areas are controlled by LFC approaches In recent decades, many control approaches have been suggested for LFC in power systems This paper presents a comprehensive literature survey on the topic of LFC In this survey, the used LFC models for diverse configurations of power systems are firstly investigated and classified for both conventional and future smart power systems Furthermore, the proposed control strategies for LFC are studied and categorized into different control groups The paper concludes with highlighting the research gaps and presenting some new research directions in the field of LFC

Challenges and Opportunities of Load Frequency Control in Conventional, Modern and Future Smart Power Systems: A Comprehensive Review

Over the past few decades, many publications have been made in the area of Load frequency control (LFC) of interconnected power systems. Load frequency control is necessary to develop better control in order to achieve less effect on the frequency and tie line power deviations after a load perturbation. However, number of control strategies has been employed in the design of load frequency controllers in order to achieve a better dynamic response and the exact choice of the LFC controller in a particular case requires sufficient expertise because each controller has its own merits and demerits. Due to this, an appropriate review of load frequency control (LFC) mechanism is essential and a few attempts have been made in this concern. This paper presents a detailed survey on load frequency control (LFC) mechanism. The overall study explores the depth study issues related to LFC mechanism based on different sources of power system models. This paper focused on different control techniques of LFC, which also includes all the recent application of FACTS devices. This review reveals the investigation of soft computing based optimization technique and application of Energy Storage System (ESS) and HVDC-link in LFC. These studies also illustrates conventional power system, deregulated of power environment as well as distributed generation and micro grids. This paper is designed in order to highlight the major traits of Load forecasting and some critical case studies on LFC.

A comprehensive state of the art literature survey on LFC mechanism for power system

The power generation from renewable power sources is variable in nature, and may contain unacceptable fluctuations in case of the wind power generation. High fluctuations in power generation may negatively impact the voltage stability of the microgrid. This problem can be alleviated by using hybrid energy storage system consisting of batteries and supercapacitors (SCs) at dc grid. A new control scheme is proposed to control the power sharing between batteries and SCs to match the generation-demand mismatch and hence to regulate the grid voltage. In the proposed control strategy, the SC supplies error component of the battery current in addition to the fast transient power demand. This added feature not only improves the dc grid voltage regulation capability but also reduces the stress levels on the battery and hence increases the life span of the battery. The main advantage of the scheme is that, the uncompensated power due to slow dynamics of the battery is diverted to the SC and keeps the state of charge within the limits for longer duration, as compared to the conventional strategy. The proposed scheme is validated through detailed experimental studies.

DC Grid Voltage Regulation Using New HESS Control Strategy

Economic load dispatch is the process of allocating the required load demand between the available generators in power system while satisfying all units and system equality and inequality constraints. Economic Load Dispatch solutions are found by solving the conventional methods such as lambda iteration, Gradient search method, Linear Programming and Dynamic Programming while at the same minimizing fuel costs, but convergence is too slow, so in order to get fast convergence and accurate results we are using artificial neural network. Artificial neural network is well-known in the area of power systems. It is a very powerful solution algorithm because of its rapid convergence near the solution. This property is especially useful for power system applications because an initial guess near the solution is easily attained. In this paper a three generator system is considered and by using lambda iteration method Economic Load Dispatch is determined and 150 patterns for different loads will be derived from same method to train neural network. As it is too slow method, we proposed a soft computing based approach i.e. Back Propagation Neural Network (BPNN) for determining the optimal flow. This method provides fast and accurate results when compared with the conventional method.

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Solution of Economic Load Dispatch problem in Power System using Lambda Iteration and Back Propagation Neural Network Methods

This paper presents the current based monitoring of induction motor for identification of bearing faults. Sensor less monitoring has many advantages over conventional vibration monitoring. The method however does not give good performance due to variable load and speed of induction motor. Due to non stationary nature of stator current, Fourier transform problems may occur. Therefore, this work presents the motor current signature analysis using wavelet analysis and compares with the FFT analysis. The proposed method has been applied to detect the bearing faults in 3 phase induction motor. It is difficult to extract the bearing fault component from stator current spectrum especially at incipient stage. Therefore, here the bearing fault can be identified by cancelling nonbearing fault component from stator current signature. The results have affirmed the effectiveness of the method.

Estimation of bearing faults in induction motor by MCSA using Daubechies wavelet analysis

The main objective of this paper is to enhance the power transfer capability of grid interfaced hybrid generation system. Generally, this hybrid system is a combination of solar and wind energy systems. In order to get maximum and constant output power from these renewable energy systems at any instant of time, this paper proposes the concept of maximum power tracking techniques. The main concept of this maximum power point tracking controller is used for controlling the Direct Current (DC) to DC boost converter. Finally, the performance of this Maximum Power Point Tracking (MPPT) based Hybrid system is observed by simulating using Matlab/Simulink.

Modelling and Simulation of Hybrid Wind Solar Energy System using MPPT

The load on the power system is always varying with respect to time which results in the variation of frequency, thus leading to load frequency control problem (LFC). The variation in the frequency is highly undesirable and maximum acceptable variation in the frequency is ± 0.5Hz. In this paper load frequency control is done by PI controller, which is a conventional controller. This type of controller is slow and does not allow the controller designer to take into account possible changes in operating conditions and non-linearity's in the generator unit. In order to overcome these drawbacks a new fuzzy load frequency controller is presented to quench the deviations in the frequency and the tie line power due to different load disturbances. The effectiveness of the proposed controller is confirmed using MATLAB/SIMULINK software. The results shows that fuzzy controller provides fast response, very less undershoot and negligible peak overshoots with having small state transfer time to reach the final steady state. In this paper for single area, two area and three area the effectiveness of fuzzy controller is verified.

Load frequency control of three unit interconnected multimachine power system with PI and fuzzy controllers

In this paper a technique is proposed to estimate the bearing faults of induction motor using sensor less monitoring. Sensor less monitoring is more suitable than conventional vibrating meters. It is very difficult to distinguish the bearing component from its current signature in nascent stage. Therefore in this work bearing fault components are estimated by cancelling the nonbearing fault components in a stator current signature. All the stator current components are treated as noise and cancelled by a wiener filter in real time fashion. Bearing faults with wide range of fault frequencies are estimated using noise cancellation. The results of different bearing faults have been affirmed by this method. Finally a threshold limit is given to intimate the severity of the faults.

M. Venu Gopala Rao

Papers

Solution of Economic Load Dispatch problem in Power System using Lambda Iteration and Back Propagation Neural Network Methods

Estimation of bearing faults in induction motor by MCSA using Daubechies wavelet analysis

Modelling and Simulation of Hybrid Wind Solar Energy System using MPPT

Load frequency control of three unit interconnected multimachine power system with PI and fuzzy controllers

Estimation of nascent stage bearing faults of induction motor by stator current signature using adaptive signal processing