Optimal Placement and Sizing of Wind Generators in AC Grids Considering Reactive Power Capability and Wind Speed Curves

This paper presents an optimization model for the optimal placement and sizing of wind turbines, considering their reactive power capacity, wind speed, and demand curves. The optimization model is nonlinear and is focused on minimizing power losses in AC distribution networks. Also, paired wind turbine and power conversion systems are treated via chargeability factor η at the peak hour. This factor represents the percentage of usage of the power conversion system in the nominal wind speed conditions, and allows to support reactive power dynamically during all periods of the day as a function of the distribution system requirements. In addition, an artificial neural network is used for short-term forecasting to deal with uncertainties in wind power generation. We assume that the number of wind power distributed generators could be from zero to three generators integrated into the system, considering unit power factors and reactive power injections to follow up the effect of reactive power compensation in the daily operation. The General Algebraic Modeling System (GAMS) is employed to solve the proposed optimization model

Master of Science

thesisA new theoretical and experimental method of induced polarization (IP) in the time domain is tested with resistivity data and detailed mineralogy of rock samples. The Generalized Effective Medium Theory of Induced Polarization (GEMTIP) was originally developed in the frequency domain for explaining the structure-property relationship of rocks. The geoelectrical parameters of this model are determined by the intrinsic petrophysical and geometric characteristics of composite media: the mineralization and/or fluid content of rocks and the matrix composition, porosity, anisotropy, and polarizability of formations. The physical properties of rock samples from exploration or mining sites are often used to assist in planning geological surveys or interpretation of geophysical results. However, electrical property data are often recorded in the time domain. In this paper, the Generalized Efective Medium Theory of Induced Polarization (GEMTIP) is tested with the time domain resistivity data transformed from complex resistivity data. It is demonstrated that the time-domain GEMTIP method can be used to study the induced polarization (IP) effect. Results indicate that the time domain resistivity data from laboratory measurements can be used in inversion routines. With advances in the understanding of the IP effect through the GEMTIP model and wide application of the time domain measurements, detection, and discrimination capability will improve for porphyry systems and other geologic targets, leading to greater efficiency in mineral exploration

Dynamic reactive power compensation in power systems through the optimal siting and sizing of photovoltaic sources

The problem of the optimal placement and sizing of photovoltaic power plants in electrical power systems from high- to medium-voltage levels is addressed in this research from the point of view of the exact mathematical optimization. To represent this problem, a mixed-integer nonlinear programming model considering the daily demand and solar radiation curves was developed. The main advantage of the proposed optimization model corresponds to the usage of the reactive power capabilities of the power electronic converter that interfaces the photovoltaic sources with the power systems, which can work with lagging or leading power factors. To model the dynamic reactive power compensation, the η-coefficient was used as a function of the nominal apparent power converter transference rate. The General Algebraic Modeling System software with the BONMIN optimization package was used as a computational tool to solve the proposed optimization model. Two simulation cases composed of 14 and 27 nodes in transmission and distribution levels were considered to validate the proposed optimization model, taking into account the possibility of installing from one to four photovoltaic sources in each system. The results show that energy losses are reduced between 13% and 56% as photovoltaic generators are added with direct effects on the voltage profile improvementUniversidad Tecnológica de Bolíva

On the mathematical modeling for optimal selecting of calibers of conductors in DC radial distribution networks: An MINLP approach

This paper addresses the problem of optimal conductor selection in direct current (DC) distribution networks with radial topology. A nonlinear mixed-integer programming model (MINLP) is developed through a branch-to-node incidence matrix. An important contribution is that the proposed MINLP model integrates a set of constraints related to the telescopic structure of the network, which allows reducing installation costs. The proposed model also includes a time-domain dependency that helps analyze the DC network under different load conditions, including renewable generation and battery energy storage systems, and different voltage regulation operative consigns. The objective function of the proposed model is made up of the total investment in conductors and the total cost of energy losses in one year of operation. These components of the objective function show multi-objective behavior. For this reason, different simulation scenarios are performed to identify their effects on the final grid configuration. An illustrative 10-nodes medium-voltage DC grid with 9 lines is used to carry out all the simulations through the General Algebraic Modeling System known as GAMS

THE MAIN RESULTS OF ARCHAEOLOGICAL RESEARCH AT REȘCA-ROMULA (1869-2019) AND CONSIDERATIONS ON THE GEOPHYSICAL APPROACH – PART II

Book Chapter in INSIGHTS OF GEOSCIENCES FOR NATURAL HAZARDS AND CULTURAL HERITAGE, Editor: Florina CHITE

Renewable Energy and Energy Saving: Worldwide Research Trends

Climate change mitigation and adaptation are key challenges of the 21st century. These challenges include global energy consumption and dependence on fossil fuels, which are addressed in global energy policies. About two-thirds of global greenhouse gas emissions are linked to the burning of fossil fuels used for heating, electricity, transport, and industry. Therefore, the world is looking for the most reliable, cost-effective, and environmentally friendly energy sources coupled with energy saving, which is a clean and low-cost solution to the growing demand for energy. As a clear example of this, cities are integrating renewable energies into their smart city plans. This book aims to advance the contribution of the use of renewable energies and energy saving in order to achieve a more sustainable world

Optimal Placement and Sizing of Wind Generators in AC Grids Considering Reactive Power Capability and Wind Speed Curves

This paper presents an optimization model for the optimal placement and sizing of wind turbines, considering their reactive power capacity, wind speed, and demand curves. The optimization model is nonlinear and is focused on minimizing power losses in AC distribution networks. Also, paired wind turbine and power conversion systems are treated via chargeability factor η at the peak hour. This factor represents the percentage of usage of the power conversion system in the nominal wind speed conditions, and allows to support reactive power dynamically during all periods of the day as a function of the distribution system requirements. In addition, an artificial neural network is used for short-term forecasting to deal with uncertainties in wind power generation. We assume that the number of wind power distributed generators could be from zero to three generators integrated into the system, considering unit power factors and reactive power injections to follow up the effect of reactive power compensation in the daily operation. The General Algebraic Modeling System (GAMS) is employed to solve the proposed optimization model