Varying the energisation condition to mitigate sympathetic inrush current

Transformers are generally easy to access and can contribute significantly to entire power system. When a transformer is turned on for the first time, it produces a magnetising inrush current which acts as a starting current. Energisation of transformer has a substantial impact on inrush current and transformer that are connected in parallel. Sympathetic inrush current is a phenomenon that appears when a transformer is switched-on in network whereas the other transformers that was earlier energised. Besides, when sympathetic inrush phenomena occur, the peak and period fluctuate significantly. In this paper, the transformers will be energised in three different ways and each condition will be explored in depth. The operation time of the transformer’s energisation whether it is energised simultaneously or at different times are tested and analysed in terms of their characteristics. It is performed using power system computer aided design (PSCAD) software, starting with a develop model of the energisation and then generate the outcomes. The results of the simulation demonstrate that energising the transformer in different ways can give different effect on the sympathetic inrush current, as well as the variables that affect it and methods for reducing it

Identifiability Evaluation of Crucial Parameters for Grid Connected Photovoltaic Power Plants Design Optimization

This paper aims to assess the impact of different key factors on the optimized design and performance of grid connected photovoltaic (PV) power plants, as such key factors can lead to re-design the PV plant and affect its optimum performance. The impact on the optimized design and performance of the PV plant is achieved by considering each factor individually. A comprehensive analysis is conducted on nine factors such as; three objectives are predefined, five recent optimization approaches, three different locations around the world, changes in solar irradiance, ambient temperature, and wind speed levels, variation in the available area, PV module type and inverters size. The performance of the PV plant is evaluated for each factor based on five performance parameters such as; energy yield, sizing ratio, performance ratio, ground cover ratio, and energy losses. The results show that the geographic location, a change in meteorological conditions levels, and an increase or decrease in the available area require the re-design of the PV plant. A change in inverter size and PV module type has a significant impact on the configuration of the PV plant leading to an increase in the cost of energy. The predefined objectives and proposed optimization methods can affect the PV plant design by producing completely different structures. Furthermore, most PV plant performance parameters are significantly changed due to the variation of these factors. The results also show the environmental benefit of the PV plant and the great potential to avoid green-house gas emissions from the atmosphere

Modelling and aggregation of loads in flexible power networks

The power system research community and industry acknowledge the importance of accurate load modelling for power system studies, however, many still use typical representation of static loads by the constant impedance/current/power load models, while dynamic loads, if represented, are usually modelled with an induction motor (IM) model. The last systematic update of load models was performed in the mid 1990s, since when significant changes have occurred in the structure, type and composition of loads at all network buses. General inadequacy of currently used load models was highlighted in several unsuccessful attempts to reproduce the behaviour observed in recent blackouts during the corresponding “post-mortem” simulations and analysis. Over the last several years, there has been a renewed interest in both industry and academia for load modelling due to appearance of new types of loads, offering increased efficiency and controllability. Different types of modern non-linear power electronic loads are now responsible for a significant part of the total demand in almost all load sectors. Furthermore, there are currently no appropriate load models available for the correct representation of various directly connected and inverter-interfaced micro and small-scale distributed generation technologies, which, in some of the future network scenarios, may strongly impact real and reactive power demands and behaviour in future network scenarios, as they would be installed in large numbers. In a response to this renewed interest in load modeling, CIGRÉ Study Committee C4 established, in late 2009, the Working Group (WG) C4.605: “Modelling and Aggregation of Loads in Flexible Power Networks”. The WG started work in February 2010 with the aim to: i) provide a critical and updated overview of existing load models and their parameters for power system studies at all voltage levels, and identify types of loads and load classes for which adequate load models are presently missing; ii) provide a comprehensive overview of existing methodologies for load modeling, with a critical overview of component based and measurement based approaches, clearly identifying their advantages and disadvantages; iii) develop a set of recommendations and step-by-step procedures for load model development and validation, using either component based or measurement based approaches, or their combination; iv) develop load models for all typical devices and classes of customers for which there are no existing models and recommend their typical parameter values and ranges; v) provide recommendations on developing equivalent static and dynamic models of networks with significant amount of distributed generation, including equivalent models of micro-grids and active distribution network cells

CIGRE WG C4.605 : “Modelling and aggregation of loads in flexible power networks”

none22The power system research community and industry acknowledge the importance of accurate load modelling for power system studies, however, many still use typical representation of static loads by the constant impedance/current/power load models, while dynamic loads, if represented, are usually modelled with an induction motor (IM) model. The last systematic update of load models was performed in the mid 1990s, since when significant changes have occurred in the structure, type and composition of loads at all network buses. General inadequacy of currently used load models was highlighted in several unsuccessful attempts to reproduce the behaviour observed in recent blackouts during the corresponding “post-mortem” simulations and analysis. Over the last several years, there has been a renewed interest in both industry and academia for load modelling due to appearance of new types of loads, offering increased efficiency and controllability. Different types of modern non-linear power electronic loads are now responsible for a significant part of the total demand in almost all load sectors. Furthermore, there are currently no appropriate load models available for the correct representation of various directly connected and inverter-interfaced micro and small-scale distributed generation technologies, which, in some of the future network scenarios, may strongly impact real and reactive power demands and behaviour in future network scenarios, as they would be installed in large numbers. In a response to this renewed interest in load modeling, CIGRÉ Study Committee C4 established, in late 2009, the Working Group (WG) C4.605: “Modelling and Aggregation of Loads in Flexible Power Networks”. The WG started work in February 2010 with the aim to: i) provide a critical and updated overview of existing load models and their parameters for power system studies at all voltage levels, and identify types of loads and load classes for which adequate load models are presently missing; ii) provide a comprehensive overview of existing methodologies for load modeling, with a critical overview of component based and measurement based approaches, clearly identifying their advantages and disadvantages; iii) develop a set of recommendations and step-by-step procedures for load model development and validation, using either component based or measurement based approaches, or their combination; iv) develop load models for all typical devices and classes of customers for which there are no existing models and recommend their typical parameter values and ranges; v) provide recommendations on developing equivalent static and dynamic models of networks with significant amount of distributed generation, including equivalent models of micro-grids and active distribution network cells.mixedJ. V. Milanović; J. Matevosiyan; A. Borghetti; S. Ž. Djokić; Zhao Yang Dong; A. Halley; L. M. Korunović; S. Martinez Villanueva; Jin Ma; P. Pourbeik; F. Resende; S. Sterpu; F. Villella; K. Yamashita; O. Auer; K. Karoui; D. Kosterev; Shu Kwan Leung; D. Mtolo; S. Mat Zali; A. Collin; Yizheng XuJ. V. Milanović; J. Matevosiyan; A. Borghetti; S. Ž. Djokić; Zhao Yang Dong; A. Halley; L. M. Korunović; S. Martinez Villanueva; Jin Ma; P. Pourbeik; F. Resende; S. Sterpu; F. Villella; K. Yamashita; O. Auer; K. Karoui; D. Kosterev; Shu Kwan Leung; D. Mtolo; S. Mat Zali; A. Collin; Yizheng X