Frequency and voltage partitioning in presence of renewable energy resources for power system (example: North Chile power network)

This paper investigates techniques for frequency and voltage partitioning of power network based on the graph-theory. These methods divide the power system into distinguished regions to avoid the spread of disturbances and to minimize the interaction between these regions for frequency and voltage control of power system. In case of required active and reactive power for improving the performance of the power system, control can be performed regionally instead of a centralized controller. In this paper, renewable energy sources are connected to the power network to verify the effect of these sources on the power systems partitioning and performance. The number of regions is found based on the frequency sensitivity for frequency partitioning and bus voltage for voltage partitioning to disturbances being applied to loads in each region. The methodology is applied to the north part of Chile power network. The results show the performance and ability of graph frequency and voltage partitioning algorithm to divide large scale power systems to smaller regions for applying decentralized controllers.Peer ReviewedPostprint (published version

Analysis of derivative control based virtual inertia in multi-area high-voltage direct current interconnected power systems

Due to increasing level of power converter-based component and consequently the lack of inertia, automatic generation control (AGC) of interconnected systems is experiencing different challenges. To cope with this challenging issue, a derivative control-based virtual inertia for simulating the dynamic effects of inertia emulations by HVDC (high-voltage direct current) interconnected systems is introduced and reflected in the multi-area AGC system. Derivative control technique is used for higher level applications of inertia emulation. The virtual inertia will add an additional degree of freedom to the system dynamics which makes a considerable improvement on first overshoot responses in addition to damping characteristics of HVDC links. Complete trajectory sensitivities are used to analyse the effects of virtual inertia and derivative control gains on the system stability. The effectiveness of the proposed concept on dynamic improvements is tested through Matlab simulation of two-area test system for different contingencies.Peer ReviewedPostprint (author's final draft

Heuristic optimization of supplementary controller for VSC-HVDC/AC interconnected grids considering PLL

This paper presents a new approach to enhance the dynamic responses of AGC in power systems by means of heuristic optimization of VSC-HVDC supplementary controllers. The upcoming power electronics-based VSC-HVDC transmission systems offer new features that would be advantageous for improving the frequency control and thus for enhancing the stability of the transmission grids. In this paper, the parameters of the proposed control modulation are tuned using Genetic Algorithm and Simulated Annealing methods. The performance of the proposed intelligent based tuning approach is assessed through MATLAB simulations for an AC/DC interconnected system. For the sake of detailed analysis, the effects of PLL and frequency measurements are also included in the VSC-HVDC system modeling. Furthermore, to show merits of the proposed strategy, a comparison between AC and DC transmissions is presented.Peer ReviewedPostprint (author's final draft

Inertia emulation in AC/DC interconnected power systems using derivative technique considering frequency measurement effects

Virtual inertia is known as an inevitable part of the modern power systems with high penetration of renewable energy. Recent trend of research is oriented in different methods of emulating the inertia to increase the sustainability of the system. In the case of dynamic performance of power systems especially in automatic generation control (AGC) issue, there are concerns considering the matter of virtual inertia. This paper proposes an approach for analyzing the dynamic effects of virtual inertia in two-area AC/DC interconnected AGC power systems. Derivative control technique is used for higher level control application of inertia emulation. This method of inertia emulation is developed for two-area AGC system which is connected by parallel AC/DC transmission systems. Based on the proposed technique, the dynamic effect of inertia emulated by storage devices for frequency and active power control are evaluated. The effects of frequency measurement delay and PLL effect on are also considered by introducing a second-order function. Simulations performed by Matlab software demonstrate how virtual inertia emulation can effectively improve the performance of the power system. A detailed eigenvalue analysis is also performed to support the positive effects of proposed method.Peer ReviewedPostprint (author's final draft

Inertia emulation in AC/DC interconnected power systems using derivative technique considering frequency measurement effects

Virtual inertia is known as an inevitable part of the modern power systems with high penetration of renewable energy. Recent trend of research is oriented in different methods of emulating the inertia to increase the sustainability of the system. In the case of dynamic performance of power systems especially in automatic generation control (AGC) issue, there are concerns considering the matter of virtual inertia. This paper proposes an approach for analyzing the dynamic effects of virtual inertia in two-area AC/DC interconnected AGC power systems. Derivative control technique is used for higher level control application of inertia emulation. This method of inertia emulation is developed for two-area AGC system which is connected by parallel AC/DC transmission systems. Based on the proposed technique, the dynamic effect of inertia emulated by storage devices for frequency and active power control are evaluated. The effects of frequency measurement delay and PLL effect on are also considered by introducing a second-order function. Simulations performed by Matlab software demonstrate how virtual inertia emulation can effectively improve the performance of the power system. A detailed eigenvalue analysis is also performed to support the positive effects of proposed method.Peer Reviewe

A review on techno-economic assessment of solar water heating systems in the middle east

Currently, the economy of Middle Eastern countries relies heavily on fossil fuel sources. The direct and indirect adverse consequences of fossil fuel utilization for power generation enforce the region’s countries to raise the share of renewable energy. In this context, various incentive policies have been developed to encourage the residential and industrial sectors to support a portion of energy needs through renewable energy resources. In this case, a solar water heating system (SWHS) as an application of solar thermal technology provides some of the heat energy requirements for domestic hot water (DHW) and space heating, supported conventionally by electricity or natural gas, or even other fossil fuels. This paper reviews the feasibility of the SWHS in the Middle East region from technical and economical standpoints and investigates some of the progress, challenges, and barriers toward this market. The pay-back times and CO2 emission reduction under different incentive frameworks and configurations of each system have been assessed in this context. Furthermore, the advantages and weaknesses of the SWHS in several countries have been reported. Finally, various guidelines have been proposed to enhance the development of this technolog

Siemens Siregraph B remote control table, Polyphos 500 generator, Sirecon 2-25 image intensifier and Videomed K TV system

SIGLEAvailable from British Library Lending Division - LD:3554.26(STB--13/83) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

A method of breaking down the cost of satellite system development

SIGLEAvailable from British Library Document Supply Centre- DSC:8053.4153(RAL--88-020) / BLDSC - British Library Document Supply CentreGBUnited Kingdo