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Generation, Transmission & Distribution, IET

Issue 1 • Date January 2012

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Displaying Results 1 - 10 of 10
  • Probabilistic determination of pilot points for zonal voltage control

    Page(s): 1 - 10
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    Owing to the local nature of voltage and reactive power control, the voltage control is managed in a zonal or regional basis. A new comprehensive scheme for optimal selection of pilot points is proposed in this study. The uncertainties of operational and topological disturbances of the power system are included to provide the robustness of the pilot node set. To reduce the huge number of probable states (i.e. combined states of load and topological changes), a scenario reduction technique is used. The resulted optimal control problem is solved using a new immune-based genetic algorithm. The performance of the proposed method is verified over IEEE 118-bus and realistic Iranian 1274-bus national transmission grids. View full abstract»

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  • Forecasting electricity prices by extracting dynamic common factors: application to the Iberian Market

    Page(s): 11 - 20
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (319 KB)  

    Developing methodology for computing accurate forecasts of electricity prices in liberalised markets is necessary to improve the bids submitted to the market operator by both consumers and producers to maximise their benefits and utilities, respectively. Here, we propose the extraction of common factors from the 24-dimensional vector of prices, and using them for one-day-ahead forecasting. This methodology is based on the Peña-Box (1987) and Lee-Carter (1992) models and is able to take into account the multivariate structure of the data. The data selected to illustrate the proposed methodology are those from the Iberian Market in the period January 2007 to January 2009, and numerical results in terms of prediction accuracy have also been compared with those by Garcĩa-Martos et al. (2007), obtaining a statistically significant improvement. For the whole period used to test the out-of-sample forecasting accuracy the authors have computed a forecast for every hour and the average MAPE is 7.39%. Furthermore, a very important feature of the proposed methodology, the Dynamic Factor Model (DFM) is that is a powerful tool for mid- and long-term forecasting. This is an important difference between DFM and other methodologies for which the accuracy dramatically degrades when increasing the forecasting horizon. View full abstract»

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  • Imperialist competition algorithm for distributed generation connections

    Page(s): 21 - 29
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    This study proposes an imperialist competition algorithm (ICA) to maximise the benefits of distribution network operators (DNOs) because of the existence of distributed generation (DG) units. The sum of active loss reduction and network investment deferral incentives has been considered as the objective function to be maximised in this study. The optimal location and size of DG units in the network are found considering various techno-economical issues. The application of the proposed methodology in the UK under current Ofgem financial incentives for DNOs is investigated. The ability of the proposed approach in finding the optimal solution is validated by comparing the obtained results with other methods of the literature. View full abstract»

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  • Online market-based rescheduling strategy to enhance power system stability

    Page(s): 30 - 38
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (877 KB)  

    The study presents a framework for online power system dynamic stability enhancement with a new market-based rescheduling approach. The objective is to solve the online transient and oscillatory stability constrained economic power dispatch problem using a mixture of a modified particle swarm optimisation (PSO) and artificial neural network. The problem is formulated as a non-linear constrained optimisation problem, and PSO has been used as optimisation tool to search for the optimal solution within the available hyperspace. For reducing the time consumed in the computations, neural network has been used to assess power system dynamic stability. The rescheduling process based on the market participants' bids is used as a remedial action to maintain system operation sufficiently away from the limits of system stability. The goal of the approach is to minimise the additional payments arising from the rescheduling needed to enhance system dynamic stability. The critical clearing time corresponding to the critical contingency is considered as an index for transient stability, while system minimum damping of oscillation is considered as an indicator for oscillatory stability. The proposed framework is implemented on a 66-bus test system, and the results obtained are found to be satisfactory. View full abstract»

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  • An approach for coordinated automatic voltage regulator–power system stabiliser design in large-scale interconnected power systems considering wind power penetration

    Page(s): 39 - 49
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    A new comprehensive criterion for the coordinated automatic voltage regulator-power system stabiliser (AVR-PSS) design in large-scale power systems is proposed. Then, a control strategy is introduced to make a trade-off between voltage regulation and small signal stability. The proposed control strategy combines switching technique and negative feedback to achieve a robust controller against load/generation disturbances. An adaptive angle-based switching strategy is employed instead of fixed time-based switching and hence the proposed control methodology takes into account system size and status modes to improve the system performance. The control strategy is completely independent of the test case and fault type. Efficiency of the proposed method has been verified on several large-scale systems and is illustrated here on the New York/New England system with and without wind power penetration. The developed control strategy can be considered as a strong tool for the coordinated design of AVR, PSS and static var compensator (SVC) in the presence of wind turbines. View full abstract»

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  • Self-scheduling approach for large consumers in competitive electricity markets based on a probabilistic fuzzy system

    Page(s): 50 - 58
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (489 KB)  

    In competitive energy markets, large energy consumers are confronted with risks associated with energy prices. As the volatility in price of electricity is higher than that of other energy sources, this problem may become more pronounced for large electricity consumers. Hence, large industries should always seek sound paradigms for maximisation of their profit considering the risk caused by uncertainty within the planning horizon. In this study, a new fuzzy-based decision-making system for procurement of electricity from different sources is proposed which helps large industries to reach a compromise between the profit and risk. The simple but efficient technique of fuzzy α-cuts is applied for modelling the mentioned electricity pool price uncertainty in our problem. By using this modelling, a decision is made to maximise the profit of a consumer for different α-cuts corresponding to different levels of uncertainty. Therefore a range of decision-making with different strategies of profit-uncertainty is established and the consumer, depending on being a risk-taker or being risk-averse, can choose the appropriate strategy. To evaluate the proposed approach, a cement factory in north-eastern part of Iran (Khorasan Province) has been selected as the industrial consumer through a 12-week scheduling plan. View full abstract»

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  • Analysis of accelerated ageing of non-ceramic insulation equipments

    Page(s): 59 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    Ageing of non-ceramic insulation can conduct into failures of the power system, where usually pollution plays an important role in the degradation process. These failures cannot be evaluated by applying IEC 61109 ageing tests, because such tests are considered as screening tests and up to now these tests are quite questionable. Therefore research of new test methods and diagnostic tools are needed to predict long-term performance of non-ceramic insulators. A non-standard method for insulation ageing is modified and used in this work to evaluate non-ceramic components of breakers, bushings and surge arresters. Different diagnostic tests are proposed to analyse the evolution in the degradation process of these apparatus. The results showed that the applied methodology and the proposed tests may evaluate in a more realistic way the performance of new non-ceramic insulating material used in electrical equipment. View full abstract»

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  • Emergence of capacity withholding: an agent-based simulation of a double price cap electricity market

    Page(s): 69 - 78
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (868 KB)  

    This study analyses a double price cap electricity market using agent-based simulation and investigates the emergence of capacity withholding, the tacit collusion behind it and its effects on market outcomes. In the context of the infinitely repeated game paradigm, the authors try to demonstrate the link between market design and tacit collusion that allows firms to behave strategically, resulting in a deterioration of economic efficiency. An optimal control problem is embedded in the supply function equilibrium (SFE) modelling framework. A feature of this method is to provide firms with a tool that is capable of bidding supply curves with vertical segments. They are then prepared to deal with slope constraints imposed by the SFE modelling. A simulation using the generation portfolio of the Iranian electricity industry illuminates the nature of tacit collusion and capacity withholding. View full abstract»

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  • Bidding analysis in joint energy and spinning reserve markets based on pay-as-bid pricing

    Page(s): 79 - 87
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    Owing to the interaction between energy and spinning reserve markets, designing proper bid functions and offering optimal prices to these markets is economically a challenging task from generation companies (GenCos) point of view, especially in the pay-as-bid pricing mechanism. A previously presented only-energy bidding method is generalised in order to model and solve a multimarket bidding problem. Considering a joint probability distribution function for energy and spinning reserve prices, the bidding problem is formulated and solved as a classic optimisation problem. The results show that the contribution of GenCos in each market strongly depends on their production costs, GenCo's risk-aversion degree and the mean values of market prices. View full abstract»

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  • Non-communication protection of parallel transmission lines using breakers open-switching travelling waves

    Page(s): 88 - 98
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (937 KB)  

    This study presents a protective algorithm for discrimination and classification of short-circuit faults on parallel circuit transmission lines. The proposed algorithm is composed of two stages. In the first stage, the cross-differential technique is employed to identify close-in internal faults. The second stage is assigned to discriminate remote faults occurring at the end part of the protected transmission line. This stage is based on the travelling waves generated by the open switching of the transmission line circuit breakers. Using these travelling waves, the algorithm can quickly identify operation of remote end circuit breakers and discriminate between internal and external faults. The proposed algorithm also classifies the faulted phases. Moreover, it covers inter-circuit faults, in which phases of both parallel circuits get involved in the fault. Extensive simulation studies were performed to evaluate the proposed algorithm performance. It is concluded that this algorithm provides a fast and reliable scheme for protection of parallel transmission lines. View full abstract»

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IET Generation, Transmission & Distribution is intended as a forum for the publication and discussion of current practice and future developments in electric power generation, transmission and distribution.

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