Primary Transmission System Research Articles

Health Index Analysis of Transmission System Components

Optimizing maintenance strategies for power transmission components is crucial to prevent failure in the system while maintaining and enhancing the overall economic efficiency. Condition-based maintenance can fulfill this and in the present paper health index-based efficient condition assessment is applied as an essential input to this type of maintenance. A method for the calculation of the health index of primary transmission system components is presented and discussed. Condition-based assessment is utilized for developing a calculation method for evaluating the health index at different levels in the system. The health index of each component is calculated by using the Weighting and Scoring Method. Several factors affecting the condition of different equipment are considered in the algorithm including environmental effects, mechanical stress, and accessibility issues. The special focus is on assigning a numeric value to the health of individual sub-components of the equipment to plan the condition-based predictive maintenance of power system components. The data indicate that in contrast to considering the health index of the entire system, making decisions considering the individual componet health indices can result in a more reliable operation.

Aided Opportunistic Jammer Selection for Secrecy Improvement in Underlay Cognitive Radio Networks

In this paper, we consider the physical-layer security for the primary system in an underlay cognitive radio model which comprises of a primary source–destination pair, a secondary receiver (SR), K secondary transmitters (STi, i = 1,…,K) and an eavesdropper (E). To protecting the transmission confidentiality of the primary transmission system against eavesdropping, we propose secondary transmitter (ST) aided opportunistic jamming transmission protocols. In our protocols, the selection of ST plays a crucial role. To this end, we propose the optimal secondary transmission selection (OSTS) and the Optimal Cooperative Jammer Selection (OCJS), respectively. For the non-security management, OSTS, OCJS schemes, we derive the closed-form expressions of the outage probability and the intercept probability for primary system, respectively. Furthermore, we also derive the closed-form expressions of the outage probability for the secondary user for the selective schemes. Numerical results show that the OCJS scheme has the best security performance and the conventional non-security management scheme has the worst security performance for primary system. In addition, the outage performances of OSTS and OCJS are better than the conventional non-security protocol in high secondary transmitting SNR region.

Efficient signal detection for cognitive radio relay networks under imperfect channel estimation

AbstractAssuming imperfect channel knowledge at the destination, we propose an improved detector for an underlay cognitive (secondary) amplify‐and‐forward wireless relay network coexisting with a primary transmission system. At first, we adjust the amplify‐and‐forward relay amplification factors by taking into account the interference temperature constraint at the primary receiver. In a second step, for the case of coherent distributed space‐time coding at the relays and maximum a posteriori signal detection at the destination, we propose a modified detector formulation. The proposed scheme reduces the impact of channel uncertainty on the receiver performance by appropriately exploiting the statistics of the channel estimation errors. Furthermore, it takes into account the interference level limitation imposed by the primary transmission system on the relays. Through some numerical results, we show that the proposed detector reduces significantly the required power level to achieve a target performance at the destination, which is of special interest for underlay cognitive radio systems. This way, the proposed receiver allows a reduction of the required protection area around the primary transmitter, leading to the increased of flexibility of the cognitive radio network design. Copyright © 2016 John Wiley & Sons, Ltd.

A LP and MILP methodology to support the planning of transmission power systems

The paper describes four optimization solutions that can be used to support the transmission system planning. The problems are focused on the identification of the primary transmission system operations that optimize the power flows on the transmission lines. The approaches are based on a DC model of the transmission system and the optimization problems can be solved recurring at LP and MILP. The mathematical model and the optimization problems have been described in detail, reporting a list of applications that can be handled by the proposed methodology to evaluate the effects on transmission and generation expansion. A 9 bus test grid has been used to support the methodology explanation.

The 60-cycle primary transmission system of the Milwaukee Electric Railway and light company

THE PRIMARY transmission system described in detail in this paper operates at 132 kv. and 66 kv. to transmit bulk energy from generating stations to step-down substations, and to interconnect the system of the Milwaukee Electric Railway and Light Company with hydroelectric plants in the northern peninsula of Michigan. The system is divided into power areas which are served directly from a generating station or from a step-down substation located near the load center of the area. Energy is distributed from these points over secondary transmission lines.

An Economic Study of an Electrical Distributing Station

This paper outlines some of the physical reasons and economic advantages influencing the establishment of Washington Park Distributing Station of the Commonwealth Edison Company of Chicago. This station is located at the electrical center of the load which it supplies. It receives energy at 66 kv. from an outlying generating station, State Line Station. The voltage is reduced at the distributing station and fed to a number of substations at 12 kv. The past practise of this company has been to feed the substations at 12 kv. directly from generating stations. However, a study indicated several reasons for discarding the practise in this case. The main physical reasons were the congested condition in the underground cable system surrounding Calumet Generating Station and the distance from Calumet Station to its dependent substations. The economic advantages consisted primarily of the decrease in transmission line costs due to the location of the distributing station at the center of the zone load and the savings resulting from the use of 66-kv. instead of 12-kv. for the primary transmission system.

An economic study of an electrical: Distributing station

This paper outlines some of the physical reasons and economic advantages influencing the establishment of Washington Park Distributing Station of the Commonwealth Edison Company of Chicago. This station is located at the electrical center of the load which it supplies. It receives energy at 66 kv. from an outlying generating station, State Line Station. The voltage is reduced at the distributing station and fed to a number of substations at 12 kv. The past practise of this company has been to feed the substations at 12 kv. directly from generating stations. However, a study indicated several reasons for discarding the practise in this case. The main physical reasons were the congested condition in the underground cable system surrounding Calumet Generating Station and the distance from Calumet Station to its dependent substations. The economic advantages consisted primarily of the decrease in transmission line costs due to the location of the distributing station at the center of the zone load and the savings resulting from the use of 66-kv. instead of 12-kv. for the primary transmission system.