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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.

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.

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.

It is becoming increasingly important for power system planning and operating engineers to be capable of performing comprehensive voltage stability analyses of the systems. This need is largely due to recent trends towards operating systems under stressed conditions as a result of increasing system loads without sufficient transmission and/or generation enhancements. This paper discusses effect of the on-load tap changing transformers (OLTCs) on voltage stability and identifying critical OLTCs to avoid possibilities of voltage instability conditions. The developed approach has been tested on sample systems. Results obtained on an equivalent system of 24-node practical power system are presented.

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.

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.

Electric power systems are exposed to various contingencies. Network contingencies often contribute to overloading 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. The paper presents an approach for selection of UPFC (unified power flow controller) 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 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.

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. 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.

Any systematic study of the effectiveness of the protection scheme of a power system in recovering from a fault requires the development of a suitable model of the protection scheme. In this paper, the relevance of Petri net models to recoverability analysis is investigated.

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.

The method of diakoptics is applied to the transient stability analysis of a power system. Diakoptics is used to obtain the transmission line power flows that are required in the step-by-step method. Through this approach, the stability studies of large power systems could be studied.