Optimal placement model of TCSC in power system network considering the budget available

Abstract: This paper presents an optimal placement of TCSC which is a FACTS (Flexible Alternative Current transmission Systems) controller in order to increase the loadbility of the system. The optimization problem is solved using the genetic algorithm. In this study the availablity of the budget is taken in consideration. The result show that the increase in loadability can be restricted by the availability of budget and also that beyond a certain budget there will not be any further increase in loadability. Also beyond a certain number of TCSC there will be no further increase in system loadability

Serving low load levels by derating line voltage using step down transformers

Abstract: Steady state voltage problems in power systems are those associated with undervoltages resulting from increasing loads. Steady overvoltages can also arise when loads served by networks are reduced, and the problem can be exacerbated if lines supplying load centres are long. This paper reports on a study that was conducted to assess the impact of derating voltage of lines, by using step down transformers on the lowest load a network can accommodate without overvoltages. A program written in Python and using PSS/E to perform loadflows, was used to perform analyses at various load levels. The study showed that with derating transformers installed, voltages in the system were better, there was less reactive power flow, and active power losses were lower. Derating lines using step down transformers is therefore a potential solution for serving low load levels

Impact of circuit-breaker maintenance on life-cycle cost comparison for fixed and magnetically controlled reactors

Abstract: Under light loading conditions, reactors provide an option for keeping voltages below steady state limits. In this paper, the impact of the number of operations of a circuit breaker on the choice of reactor technology (i.e. fixed versus magnetically controlled) is studied. In particular, the impact of circuit-breaker maintenance cost on the life-cycle cost of a reactor installation is evaluated. The study shows that when the expected number of circuit-breaker operations is high, it is beneficial to consider the use of a magnetically controlled reactor as this leads to very few operations. In addition, the savings in circuit-breaker maintenance cost can justify the extra cost of a magnetically controlled reactor over its life cycle. The economic life-cycle cost assessment can help to identify the lowest cost solution over the project life cycle

Increasing the capacity of transmission lines via current uprating: an updated review of benefits, considerations and developments

Abstract: Constraints to power transfer in the network may limit the load that can be supported by the transmission lines. To overcome these constraints various current uprating methods can be used. This paper discusses the developments in the use of Dynamic Line Thermal Rating (DLTR) techniques to obtain a higher rating of conductors, the general considerations for thermal uprate and High Temperature Low Sag (HTLS) conductor usage in uprating

Statistical analysis of forced outage durations of Eskom subtransmission transformers

Abstract: The main aim of this paper is to analyse the duration of forced outages of Eskom subtransmission transformers. Statistical techniques are used to analyse events recorded from 2007–2016. For various event variables, boxplots were plotted for various levels to understand and compare the distribution and spread of durations. Thereafter, the Kruskal–Wallis test was conducted to assess whether there was a variation in the durations for various levels of variables. Finally, multiple linear regression models were constructed with each variable as an independent variable against the duration as the dependent variable. The coefficients of determination for the models were calculated and used in ranking variables as predictors of duration. The study has demonstrated how insight into the duration of forced outages can be obtained by using statistical techniques. This insight can provide useful inputs to asset and performance managers when developing strategies for reducing the duration of forced subtransmission transformer outages

Decomposition forecasting methods : a review of applications in power systems

Abstract: The aim of this paper is to present a comprehensive literature review on the application of decomposition methods of time series forecasting in power systems. A comprehensive search is conducted, relevant publications are identified and summarised in terms of the aim of the forecast, decomposition forecasting method used, and a comparison is made with other forecasting techniques. Moreover, publications are analysed by number of publications per year, number of papers by the decomposition method used, and number of publications by area of application of the method in power systems. It is shown that the number of publications per annum grew substantially after 2014 due to studies on the application of decomposition methods in forecasting distributed generation output. Of the methods of forecasting, most publications have used multiplicative decomposition, a lower number has used additive decomposition, with the balance of the papers only using decomposition of the time series as an initial phase towards forecasting using other techniques. The analysis of the papers also shows that decomposition methods have been used in power systems mainly for load, price and distributed generation forecasting. The review contributes to literature by providing an extensive overview of the papers and a repository of references to researchers interested in decomposition forecasting techniques