A utilizacao de redes de media tensao monofasicas, a um ou dois condutores, representa uma alternativa bastante difundida no setor eletrico brasileiro para o atendimento a cargas rurais, notadamente em funcao dos baixos investimentos associados comparativamente as redes trifasicas de distribuicao de energia eletrica. Muito embora tais topologias de rede consigam atender a maioria das necessidades destas instalacoes, particularidades relacionadas com a necessidade de utilizacao de cargas motrizes mais significativas por parte de alguns consumidores rurais, orientam para o emprego de motores trifasicos. Comumente, a solucao para o problema tem sido a substituicao do ramal monofasico do consumidor rural por um novo ramal de topologia trifasica, com custos elevados e muitas vezes inviaveis tanto para o consumidor quanto para as concessionarias de distribuicao. Em algumas ocasioes, sao tambem utilizados sistemas conversores de numero de fases, baseados em eletronica de potencia. Diante desse cenario, o presente trabalho visa colaborar com a expansao do mercado de energia eletrica em areas rurais, oferecendo uma possibilidade inovadora para solucao do problema atraves do aproveitamento da topologia fisica dos ramais monofasicos existentes nas instalacoes rurais para o suprimento trifasico as mesmas instalacoes, usando uma nova concepcao de transformacao de numero de fases, baseada tao somente em unidades magneticas. O sistema proposto de suprimento trifasico a dois condutores tem sua concepcao analisada fisica e matematicamente sob distintas condicoes de carga e suprimento, alem de ser modelado, simulado computacionalmente e ter sua eficacia experimentalmente comprovada. Fundamentado nestes principios, o trabalho evidencia que a proposta se mostra construtivamente simples, oferece baixos requisitos de manutencao e exige investimentos extremamente atrativos.%%%%The use of single-phase medium-voltage grids with one or two wires represents a very widespread alternative in Brazilian electricity sector to supply rural loads, mainly because of the associated low investment when compared to the three-phase power distribution grids. Although such network topologies are capable to meet most of the needs of these facilities, specific features related to the need of using more expressive driving loads by some rural consumers recommend the employment of three-phase motors. Commonly, the solution for the problem has been the replacement of the single-phase branch of the rural consumer by a new branch with three-phase topology which is more expensive and often unfeasible for both the consumer and the distribution utilities. On some occasions, systems to convert the number of phases are also used, all based on power electronics. Given this scenario, this work aims to contribute to the expansion of the electricity market in rural areas, offering a distinct possibility for solving the problem by exploiting the physical topology of the single-phase branches existing in rural facilities to supply the same premises using a new concept to…

https://repositorio.ufu.br/bitstream/123456789/14337/1/SistemaDistribuicaoEnergia.pdf

Sistema de distribuição de energia elétrica a dois condutores para atendimento a cargas rurais trifásicas

This paper presents a capability study of a static converter system to provide balanced three-phase four-wire with grounded neutral from single-phase network. The system is connected in parallel with the single-phase grid, that matches one of the output three-phase terminal. The converter absorbs active power from single phase grid to produce two additional phases of the three-phase system. Furthermore, it allows the voltage compensation or power factor correction through reactive power injection. This system also allows the connection of alternative sources to DC bus.

Capability analysis of a D-STATCOM integrated to a single-phase to three-phase converter for rural grids

Currently, the supply of electricity to rural districts is realized, in almost all cases, through single-phase medium-voltage overhead distribution lines. However, some of these installations will eventually demand the use of more expressive electrical loads, which makes the use of three-phase distribution systems a necessity, thus bringing about the substitution of the existing single-phase network. Some of the more usual techniques, based on power electronics, make the supply of three-phase loads possible from converters especially developed for single- to three-phase transformation. In this context, this article presents a new and innovative low-cost methodology, based on electromagnetic arrangements, without the use of power electronics, for attending to rural three-phase supply needs through the use of a new overhead two-wire distribution system.

Two-Wire Distribution System for Supplying Three-Phase Rural Loads

This paper presents a single-phase voltage distribution static synchronous compensator which integrates a single-phase to three-phase four-wired transformer-less conversion. Beyond that, this structure are capable to interface a distributed alternative energy generation to the mains. The major advantage of this circuit is the combined operation capability, which is realized with a few switching components while preserve an interconnected grounded neutral from mains to three-phase terminals. The power electronic circuit is parallel connected to the single-phase grid and add two additional terminals, which together, form the three-phase four-wired grid. The resulting active power from the converter energy balance are absorbed/delivered from/to the mains while the reactive power are managed to provide its single-phase voltage compensation. The power system scheme as well as the proposed closed-loop control structure are presented in details. Simulation results are illustrated to validate the converter assembly.

Distribution STATCOM integrated to a single-phase to three-phase converter

In recent years, China gradually put more resources in the DDS study, but it is relatively far from the international level, especially in the aspect of DDS hardware design. So, according to the status mentioned above, it was described in detail about how to simulate and achieve a DDS based FPGA in this paper. Firstly, the frame of DDS based FPGA was constructed and the algorithm was analyzed, the module be plotted as well. And on this basis mentioned, the Verilog HDL language was used to execute RTL-level functional simulation and write testing platform, and then all the digital parts design and simulation and even the timing analysis as well as the synthesis optimization were completed. To meet the requirements of high-frequency and low jitter, the synthesis repeated several times and such factors as timing, area, power consumption were fully considered, the simulation result after layout was proved closed to the actual waveform. There are better results in the design of each functional module in the synthesis, as well as timing, area, power and other aspects, and it was proved to meet the engineering design requirements and have greater reusability and practicality.

The Front Design and Implement of Direct Digital Frequency Synthesizer Based on FPGA

This work presents the experimental development of a four-wire single-phase to three-phase static converter for rural distribution system. The converter topology is based on a front-end full-controlled PWM rectifier that handles the DC bus voltage regulation as well as improves the input power factor correction. In order to provide the three-phase four-wire system, a four-legged PWM voltage source inverter (VSI) is used at the output. The rectifier-inverter control strategy has been implemented in a digital processor (DSP), where a proposed PLL algorithm performs the rectifier synchronism. Component specification guidelines and control strategies are described. Complete models are implemented in an electromagnetic transient simulation package (PSCAD/EMTDC/spl trade/), where the converter is connected to a rural distribution network and is supplying three-phase and single-phase loads. Simulation results show that this converter can ride through a typical voltage sag condition that is very often in rural areas. The converter topology is composed of 12 IGBTs and can be implemented by two off-the-shelf three-phase PWM inverters. This availability can offer significant cost reduction. Experimental results are provided.

Ud.A. Miranda

Papers

Four wire single-phase to three-phase system for rural distribution network