Power systems are prone to frequent faults, which may occur in any of its components, such as generating units, transformers, transmission network and/or loads. It is well known that faults can cause significant disruption of supply, destabilize the entire system and may also cause injuries to personnel. Detection of faults is therefore of a paramount importance from economic and operational viewpoints. In addition faults should be detected as quickly as possible, in real time if possible, so that an appropriate remedial action can be promptly taken before major disruptions to the power supply can occur. Neural networks are based on neurophysical models of human brain cells and their interconnection. Such networks are characterized by exceptional pattern recognition and learning capabilities. The major advantage of the neural networks is its self-learning capability. First, the network is presented with a set of correct input and output values. Then it adjusts the connection strength among the internal network nodes until proper transformation is learned. Second the network is presented with only the input data, and then it produces a set of output values. An Artificial Neural Network (ANN) can be described as a set of elementary neurons that are usually connected in biologically inspired architectures and organized in several layers. The structure of a feed-forward ANN, also called as the perceptron is shown. There are Ni numbers of neurons in each ith layer and the inputs to these neurons are connected to the previous layer neurons.
impedance increases significantly after fault occurrence. In addition, the algorithm uses a voltage signal to detect saturation and thus can cause an increase in the operating time. A microprocessor-based bus bar protection system that estimates the impedances of the positive- and negative sequence circuits for every feeder connected to the busbar was proposed by Gill et al. . The basic idea of the algorithm is similar to phase angle comparison. It compares the direction of current flow for each feeder and consequently is less dependent on the effect of CT saturation than a magnitude comparison algorithm . The technique detects an internalfault if all the impedances seen by every feeder are located in the third quadrant of the impedance plane. The performance of the technique is satisfactory for mild saturation. However, correct operation of the technique is not guaranteed for severe saturation caused by a high level of remnant flux. Moreover, the technique requires significant computational burden as compared with phase angle comparison, since it calculates the positive- and negative sequence components of the voltages and currents for every feeder. Yong-Cheol Kang et al., has proposed a bus differential relay which operates in conjunction with a saturation detection algorithm based on the third-difference function applied to the current signal 
This chapter presents a new directional comparison-based internal/external fault detection and discrimination algorithm for the protection of all commonly used phase shifting transformer types. Like traditional differential protection, the proposed solution offers distinguished features such as speed and selectivity. However, unlike PST differential techniques, the proposed algorithm offers great reliability. It provides a secure operation during conditions such as current transformer (CT) saturation, magnetizing inrush, core saturation, any mismatch between CTs and zero-sequence current, etc. Moreover, unlike the differential solution, the proposed algorithm solves the problem of non-standard varying phase shift without tracking the tap-changer position. Performance analysis of the proposed algorithm shows that the algorithm provides the best overall protection solution for commonly used single/two-core symmetrical/asymmetrical PSTs. In addition, this work also explores and investigates the various problems associated with this technique when applied to a PST. Solutions to these problems are proposed by modifying the basic directional criteria and algorithm to ensure the sensitivity and security of the technique. The concept of directional comparison-based protection techniques has already been proposed and investigated for the detection of a fault on the busbar , , , , standard transformer , transmission lines , , synchronous generator  and phase selection .
A Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure or a mis-operation of end user equipments. Utility distribution networks, sensitive industrial loads and critical commercial operations suffer from various types of outages and service interruptions which can cost significant financial losses. With the restructuring of power systems and with shifting trend towards distributed and dispersed generation, the issue of power quality is going to take newer dimensions. In developing countries like India, where the variation of power frequency and many such other determinants of power quality are themselves a serious question, it is very vital to take positive steps in this direction .This paper presents a study on the modeling of a STATCOM (Static Synchronous Compensator) used for reactive power compensation on a distribution network. This paper deals with the simulation of distribution static synchronous compensator (DSTATCOM) for improving power quality of a distribution system feeding linear as well as non-linear loads. Nowadays, there are an increasing number of non-linear loads which inject harmonics into the system. A three-phase insulated gate bipolar transistor- (IGBT-) based current controlled voltage source inverter with a DC bus capacitor known as a DSTATCOM is used for power factor correction, harmonic compensation and for providing required reactive power to the load. A model of DSTATCOM connected to a power distribution system feeding linear and non-linear loads (diode bridge rectifier with R and R-C) is developed for predicting the behavior of system under transient conditions. Simulation is carried out in standard MATLAB environment using Simulink and power system block set toolboxes. Finally the performance of DSTATCOM under various fault conditions is investigated.
Results: The validation involved 682 patients and 437 family carers, interviewed in 8 different languages. Phase 1. Qualitative interviews (N = 90 patients; N = 38 carers) showed POS items mapped well onto identified needs; cognitive interviews (N = 73 patients; N = 29 carers) demonstrated good interpretation; Phase 2. POS-MVQoLI Spearman ’ s rank correlations were low-moderate as expected (N = 285); Phase 3. (N = 307, 2nd assessment mean 21.2 hours after first, SD 7.2) Cronbach ’ s Alpha was 0.6 on both datasets, indicating expected moderate internal consistency; test-retest found high intra-class correlation coefficients for all items (0.78-0.89); median time to complete 7 mins, reducing to 5 mins at second visit.
The Electrical Power System consists of many vital components. Among them, the Transmission lines are one of the most important parts of the system. Faults occur in transmission lines have high impact on the electrical power system. The major fault in transmission line is single line to ground (L-G) fault, but, various types of faults also occur in transmission line, such as unsymmetrical faults which includes single line to ground (L-G) fault, double line to ground (L-L-G) fault and line to line (L-L) fault and symmetrical faults which are three phasefault. So, the protection relays are needed to protect transmission lines from various types of faults. Overcurrent and earth fault relay is normally used to protect transmission lines, distribution lines, transformers and bus coupler etc. Moreover, these relays can be used as main or backup protection. The modeling of protection relays is required to determine the effects of network parameters and configurations on the operation of these relays. This paper presents the modeling and simulation of standard inverse definite minimum time (IDMT) relay using MATLAB/SIMULINK software. The study of test system is Paunglaung – Pyinmana High Voltage transmission line. The proposed model was tested for single line to ground (L-G) fault and three phasefault witha fault resistance (0.001 Ω )at various locations. The simulation results obtained by MATLAB software show the feasibility analysis of High Voltage Transmission Line with Overcurrent and Earth Fault relay.
The lecithin product used in these experiments was derived from soybean, and is commonly used as a hydrophobic emulsifier in food W/O emulsions, such as margarine and chocolate. However, in this study, lecithin functioned poorly in the present formulation and processing conditions. Separation of water droplets was detected in W/O emulsion and EE of dye was very low. Gaonkar (1992) found that the addition of electrolytes (e.g. sodium phosphate buffer in this study) in emulsions increased the concentration of surface-active impurities from commercial vegetable oil at the oil-water interface and reduced interfacial tension. Lecithin-stabilized W/O emulsions were found to be sensitive to the presence of surface-active impurities in the oil phase. The stability of W/O/W emulsions with lecithin as hydrophobic emulsifier was reduced and interfacial film breakdown and rapid coalescence of water droplets were observed (Knoth et al., 2005; Scherze et al., 2006). The detrimental effect of electrolytes on lecithin-stabilized W/O emulsions could also be attributed to electrostatic effects caused by the inherent structure of lecithin. In the presence of electrolytes, the polar heads of phospholipids in lecithin may repel each other by electrostatic repulsion, and their close association may be reduced, therefore reducing the emulsifying efficiency (Doig and Diks, 2003).
1) Case-1: Normal loading, 3-phasefault disturbanceThe effectiveness of HPSOGSA optimized SVC controller for damping the oscillation and stability enhancement is first accessed at nominal loading condition (Pe = 0.85pu, δ0 = 51.510) under three phase faults. A 3-phase, 3 cycle fault is created in the middle of one transmission line linking bus2 and bus3 shown in fig. 5 at time t=1 second the fault line is tripped in order to clear the fault and is automatically reclosed after 3 cycles. The response, without control (without PSS and SVC controller) is shown with blue line and respond to control (with SVC and PSS controller tuned HPSOGSA) is shown with a red line is superior response. The original system condition is regained after fault clearance. The response of the system under this fault is shown in fig. 6 to fig.10.
increase both accuracy and cost. Impedance based techniques that use the fault generated high frequencies were reported in [7, 8]. These wideband techniques have the advantage of using a short data window, hence they could be implemented in real time applications with a fast response time. Travelling wave techniques detect the high frequency waves reflected from the fault point and use the arrival time for these waves to the measurement point(s) to estimate the fault distance . Despite of being fast and accurate, they require very high sampling rates in range of MHz or even GHz. Also, for application with distribution systems, the waves will suffer from more reflections and attenuation due to presence of loading taps and lateral connections. Therefore, the implementation of travelling wave based techniques in distribution systems is complex and cost intensive. Artificial intelligence based techniques employ a heuristic way of using the data collected from the system. Using artificial neural networks is an example for such techniques . These methods require extensive training (and retraining if the system topology changes) to accommodate for all possible fault scenarios. Techniques that can benefit from devices installed along the system such as smart meters or fault indicators have been reported [11, 12]. Usually these methods define the closest bus to the fault point instead of the actual fault position. In , a method based on matching the recorded voltage sag and the calculated voltage sag simulated at all system nodes was presented: the system node with the highest match is considered to be the faulty or closest node to the fault point. The benefit behind the method is the ability to locate sub- cycle faults. However, it assumed the availability of measurements at all system nodes and will fail if this is not available.
Electric power generation by exploring the use of renewable energy source is viable solution for reducing the dependency of fast depleting fossil fuels and to fit into the environmental conditions. Among all existing non-conventional sources wind has latent qualities that can be utilized to meet the heaping energy demand . Self-excited induction generators (SEIGs) are usually deployed for wind energy conversion system in standalone applications with its inherent characteristics as mentioned in [2-3]. Later they also operated in grid connected mode for distributed power generation in hybrid micro grids . However they are suitable for low and medium power applications . MPIG with more than three phases is a potential contender which combines the advantages of MPIG with SEIG technologies yielding an efficient, reliable and fault tolerant machine which finds diverse application. [5-8]. Multiphase systems can be employed for different applications, such as offshore energy harvesting, electrical vehicles, electric ship propulsion and aircrafts. The earlier proposed research works brief the supremacy of multiphase machines to obtain a better reliable performance [9-14].
• Inter-turn short circuits are also due to voltage transients that can be caused by the successive reflection resulting from cable connection between motors and ac drives. Complete short circuits of one or more phases can occur because of phase loss, which is cause by an open fuse, contactor or breaker failure, connection failure, or power supply failure.
Extraction results are shown in Figure 3(d). For all three cases, copper extraction was much faster than nickel extraction, and an almost quantitative removal of copper took place within seven minutes at a maximum copper concentration of 5760 mg/L, while a maximum of 34% nickel removal took place with an initial nickel concentration of 1570 mg/L in the same time duration. This pattern is attributed to the same factors discussed in the previous section. Copper gets loaded faster, and this induces a large flux of copper-oxime complex directed inwards within the emulsion. All peripheral internalphase droplets are depleted of their acid content to strip the copper, and hence nickel has to diffuse deeper to get stripped. The slow rate of extraction observed for nickel is additionally contributed by the slow stripping rates of nickel in ELMs. The histogram shown in Figure 4(d) bears testimony to these ideas.
Faults in the TPS and other processing units in the oil and gas industry are commonly detected by using either thresholds of the process variables 2 (e.g. oil level, water level and etc.), statistical analysis of the process variables 3-6 or precise mathematical models 7-10 simulating the operation of the TPS and then comparing its outputs with the readings obtained from the actual separator. The first approach usually detects failures when their effect is already critical and prevention of the separator shut down is unavoidable. Moreover, observing the readings from individual sensors and comparing them to threshold values might hide certain failure modes (level transmitters stuck on the last reading) unless comparison between several sensors is not performed. The second approach needs historical data of the process variables under fault free and faulty operation, which might not always be available in practice, especially for the hazardous failure modes. Finally, the detailed mathematical model approach needs a very good understanding of the process conditions and usually requires extensive modifications if operating conditions change.
Abstract:-This paper proposes an algorithm for detecting, classifying and locating single phase to ground faults on electric power 415 volts distribution lines. Feedforward artificial neural networks have been employed along with backpropagation algorithm for each of the three steps in the fault location process which are fault detection, fault classification and fault location. To validate the proposed algorithm, the Michael Okpara University of Agriculture Umudike plant house to new female hostel415 volts distribution line is modelled using Power System Computer Aided Design power systems analysis tool.Simulation results have demonstrated that the fault location method has high accuracy and good robustness. After the test set has been fed into the neural network and the results obtained, it was noted that the efficiency of the neural network in terms of its ability to detect the occurrence of a fault was near precision. The confusion matrices show that the chosen neural network has 100 percent accuracy in fault detection. The artificial neural network chosen for fault detection, fault classification and fault location satisfies the mean square errorgoal of 0.001 by approximately 100 percent. The overall correlation coefficient of the various phases of training, validation and testing for the artificial neural network chosen for fault detection, fault classification and fault location is averagely 99 percent which indicates that the neural network target is able to track the variations in the neural networks outputs very well. The gradient and validation performance plots shows a steady decrease in the gradient and the number of validation fails is zero which indicates smooth and efficient training. This further implies that the neural network can generalize new data fed into it more effectively. The test phase performance shows that the average percentage error obtained for the neural network chosen for fault location for the single phase to ground faults is below 0.5 percent which is very satisfactory and thus the neural network can be used for the purpose of single phase to ground fault location.
Along with other electrical components, the transmission line suffers from the unexpected failures due to various faults. Protecting of transmission lines is most important task to safeguard electric power systems. For safe operation of transmission line systems, the protection systems should be able to detect, classify, locate accurately and clear the fault as fast as possible to maintain stability in the network. The protective systems are required to prevent the propagation of these faults in the system. The occurrence of any transmission line faults gives rise to the transient condition which may lead to the instability of the system. The purpose of a protective relaying system is to detect all theabnormal signals indicating faults on a transmission system. After detection of the fault, the faulted part should be isolated from the rest of the system to prevent the fault propagation into healthy parts.Transmission line relaying involves three major tasks: fault detection, fault classification and fault location. Fast detection of a transmission line fault enables quick isolation of the faulty line from service and protects it from the transient effects of the fault.
In all three cases, SPIM is transformed to an asymmetrical four-phase machine. The projected space voltage vectors on a four-dimensional decoupled space are shown in Tables 3-5. Opening three phases: In this case, one may recognize three different configurations for opened phases, that are phases 123, phases 124, and phases 135. In the first and second case, SPIM transforms to an Asymmetrical three- phase machine, and in the opening phases 135, the SPIM transforms to a symmetrical three-phase machine. The projected space voltage vectors to a three dimensional decoupled space are shown in Tables 6 to 8. It seems from Tables 3 to 7, for every non-zero projection on the α and β axes, one may not find zero or near zero components on the z-axis. In this case, the root mean square (rms) of total z-axis component voltages is introduced as a norm for (9)
Abstract Multi-phase Induction motor drives (MPIMD) with numerous advantages dominates three-phase drives and emerges as a potential contender and viable solution for the high power electric drive applications. When multi-phase AC drives fed from voltage source inverters (VSIs) requires a suitable PWM method of control. This paper investigates the performance of 3- ϕ and 5-ϕ induction motor drive with various PWM techniques. First, a 3- ϕ and 5-ϕ VSI model is compared with different open fault conditions to show the fault tolerant capability of 5- ϕ induction motor drive. Next, PWM switching techniques are designed for 5-ϕ VSI fed induction motor drive for an efficient control. The suitable switching technique is identified by setting the high fundamental voltage with reduced %THD in the output voltages. The proposed scheme uses the full DC bus voltage, and the output response superior with low lower order harmonics than the conventional sinusoidal pulse width modulation (SPWM) methods. The performances of the 5-ϕ VSI fed IM drive tested with various switching techniques, and the results observed in terms of harmonic contents present in the output voltage waveform. MATLAB/Simulink software results included in this paper to show and verify the theoretical concepts.
If any fault occurs in a power system, the faulty element must be isolated from the power system as soon as possible to maintain the power system stability and also to safe guard the equipment. The fault current may be more than ten times of the normal full-load current. If these fault currents persist even for a short time, they will cause extensive damage to the equipment that carries these currents. Over-currents, in general, cause overheating and attendant danger of fire. Overheating also causes deterioration of the insulation, thus weakening it further . Not so apparent is the mechanical damage due to excessive mechanical forces developed during an over-current. Transformers are known to have suffered mechanical damage to their windings, due to faults. This is due to the fact that any two current-carrying conductors experience a force. This force goes out of bounds during faults, causing mechanical distortion and damage.
IHR the non cluster head nodes will select few targets and helps in data transmission. This algorithm consumes less energy. The wireless sensor networks are implemented in the medical field, battlefield surveillance, military, monitoring and tracking system and biological detection systems. The sensors monitor the environmental conditions in soil, marine and atmospheric context. An algorithm is proposed to cover entire monitored region with minimum number of sensor nodes. The redundant nodes are found out and it is used to replace the fault node. The mobility assistance minimum connected sector cover (MCSC) consumes minimum amount of energy and it prolongs the lifetime of the network. It uses either direct movement or cascaded movement to replace the faulty node and it reduces the distance location. . In , this paper discusses about different approaches in fault tolerance in Wireless sensor networks. As the sensor nodes are deployed randomly in a hostile environment, the fault tolerance and reliable dissemination are major issues in WSN. The wireless communication plays an important role in data processing networks. They do not need infrastructure and also it provides mobility. Due to the mobility of the users, they were under active deployment. The characteristics of the mobile environment include frequent disconnection, limited source of energy. Since the major number of nodes will have a low power battery for their power source and it can’t be replaced as the sensor nodes are deployed in the battlefield, civil and military environment, etc. So energy should be utilized properly to extend the lifetime of the network. DFRN: Detection and replacement approach of a failing node helps in fault tolerance in wireless sensor networks using connected dominant sets CDS) gives solution to the fault tolerant issue. It works like