The role of morphology of the thumb in anthropomorphic grasping : a review

The unique musculoskeletal structure of the human hand brings in wider dexterous capabilities to grasp and manipulate a repertoire of objects than the non-human primates. It has been widely accepted that the orientation and the position of the thumb plays an important role in this characteristic behavior. There have been numerous attempts to develop anthropomorphic robotic hands with varying levels of success. Nevertheless, manipulation ability in those hands is to be ameliorated even though they can grasp objects successfully. An appropriate model of the thumb is important to manipulate the objects against the fingers and to maintain the stability. Modeling these complex interactions about the mechanical axes of the joints and how to incorporate these joints in robotic thumbs is a challenging task. This article presents a review of the biomechanics of the human thumb and the robotic thumb designs to identify opportunities for future anthropomorphic robotic hands

Selection of UPFC Suitable Locations for System Security Improvement Under Normal and Network Contingencies

Absfracr-Electric power systems are exposed to various contingencies. Network contingencies often contribute to over-loading of network branches, unsatisfactory voltages and also leading to problems of stability/voltage collapse. To maintain security of the systems, it is desirable to estimate the effect of contingencies and plan suitable measures to. improve system security/stability. This paper presents an approach for selection of' UPFC suitable locations considering normal and network contingencies after evaluating the degree of severity of the contingencies. The ranking is evaluated using composite criteria based fuzzy logic for eliminating masking effect. The selection of UPFC suitable locations uses the criteria on the basis of improved system security/stability. The proposed approach for selection of UPFC suitable locations has been ~ tested under simulated conditions on a few sample power systems and the results for a real life 36-node equivalent EHV power network are presented,for illustration purposes

Optimum allocation of reactive power for voltage stability improvement in AC-DC power systems

The dependence of the system voltage stability on reactive power distribution forms the basis for reactive power optimisation. The technique attempts to utilise fully the reactive power sources in the system to improve the voltage stability and profile as well as meeting the reactive power requirements at the AC-DC terminals to facilitate the smooth operation of DC links. The method involves successive solution of steady-state power flows and optimisation of reactive power control variables using linear programming techniques. The proposed method has been applied to a few systems and the results obtained on a real-life equivalent 96-bus AC and a two-terminal DC system are presented for illustration

Improvement of system security with unified-power-flow controller at suitable locations under network contingencies of interconnected systems

The operation and planning of large interconnected power systems are becoming increasingly complex. To maintain security of such systems, it is desirable to estimate the effect of contingencies and plan suitable measures to improve system security/stability. The paper presents an approach for selection of unified-power-flow-controller (UPFC-) suitable locations considering normal and network contingencies after evaluating the degree of severity of the contingencies. The ranking is evaluated using composite-criteria-based fuzzy logic for eliminating masking effects. The fuzzy approach, in addition to real-power loadings and bus-voltage violations, also used voltage-stability indexes at the load buses as the post-contingent quantities to evaluate the network-contingency ranking. The selection of UPFC-suitable locations uses the criteria on the basis of improved system security/stability. The proposed approach for selection of UPFC-suitable locations has been tested under simulated conditions on a few power systems and the results for a 205-node real-life equivalent regional-power-grid system of three interconnected utility systems are presented for illustration purposes

An Approach for Real Power Scheduling to Improve System Stability Margins under Normal and Network Contingencies

In the present day power system planning and operation, considerable interest is being shown in system security and stability analysis. Pattern of load sharing / generation scheduling that results in heavy flows tend to incur greater losses, threaten stability, security and ultimately making certain generation patterns undesirable. Generation schedules mainly based on economic criteria may lead to lower reserve margins and therefore diminished reliability is a serious concern for the systems. With increased loading of existing power transmission systems, the problem of voltage stability and voltage collapse has also become a major concern in power system planning and operation. While the voltage stability is more dependent on the reactive power sources/voltage profile in the system, it is also a function of real power flows. In this paper, network sensitivity between load voltages and source voltages to compute voltage stability index (L), is used as the basis to evaluate desirable load sharing for improving stability margins. The proposed method has been tested on typical sample systems and also on a practical 24-bus equivalent power system, and results are presented to illustrate the proposed approach

Transmission charges of power contracts based on relative electrical distances in open access

Transmission charge allocation is one of the major issues in transmission open access faced by the electric power industry. This paper introduces a new method of transmission charge allocation based on relative electrical distance (RED) concept. The method estimates the relative locations of load nodes with respect to the generator nodes. Transmission charges are allocated based on the relative electrical distance and the power contracts. The proposed method has been tested on typical sample systems and also on a practical 24-bus equivalent EHV power system, and results are presented for illustrative purpose. The proposed method provides better transmission tariff for maintaining system stability margins, minimum transmission loss and relieving congestion on lines

An approach for evaluation of transmission costs of real power contracts in deregulated systems

This paper presents a usage-based transmission cost allocation method based on a new set of line utility factors (LUFs), which provides power transaction impact on each element of the network in deregulated power system operation. The developed LUFs relates the line flows with generation/load for a given network configuration. In this paper, a bilateral transaction contract model through a transaction matrix and line utility factors are used to evaluate cost of bilateral power contracts. The proposed method allocates the transaction costs over the participants/contracts proportional to the ratio of power flow caused by each participant/contract and the total power flows on a designated transmission line. The method has been applied on a few sample systems, and the results for sample systems and a real life EHV equivalent system are presented for illustrative purposes

Application of UPFC for system security improvement under normal and network contingencies

Electric power systems are exposed to various contingencies. Network contingencies often contribute to over-loading of network branches, unsatisfactory voltages and also leading to problems of stability/voltage collapse. To maintain security of the systems, it is desirable to estimate the effect of contingencies and plan suitable measures to improve system security/stability. This paper presents an approach for selection of unified power flow controller (UPFC) suitable locations considering normal and network contingencies after evaluating the degree of severity of the contingencies. The ranking is evaluated using composite criteria based fuzzy logic for eliminating masking effect. The fuzzy approach, in addition to real power loadings and bus voltage violations, voltage stability indices at the load buses also used as the post-contingent quantities to evaluate the network contingency ranking. The selection of UPFC suitable locations uses the criteria on the basis of improved system security/stability. The proposed approach for selection of UPFC suitable locations has been tested under simulated conditions on a few power systems and the results for a 24-node real-life equivalent EHV power network and 39-node New England (modified) test system are presented for illustration purposes

A three phase fault detection algorithm for radial distribution networks

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