Ring Distribution Network Research Articles

Evaluating the effect of considering repairing-fault periods on calculating technical losses in medium-voltage feeders of ring distribution networks

Energy losses represent one of the main challenges for electric power distribution utilities all over the world. Several papers presented different methods for estimating technical losses (TLs) in distribution networks. Due to load variation during normal operation, load factor (LF) and loss factor (LSF) coefficients are considered. In this paper, the effect of repairing fault periods (RFPs) on calculating the TLs for medium voltage feeders of ring distribution network is presented. For emphasizing this effect, comparisons between TLs calculation considering only normal operation period (NOP) and considering both NOP and RFP are introduced. A proposed factor is suggested to be inserted into equations of TLs calculation to express the effect of RFPs. A proposed formula is introduced to calculate the new factor depending on repairing fault hours over the year. An actual ring distribution network in Egypt is chosen for evaluating the proposed study according to real data and measurements.

Power Flow Analysis and Optimization in Ring Distribution Network of Bahawalpur using Newton Raphson Method

Background: The primary motive of an electrical power system is to generate and supply electric power efficiently and reliably to the consumer-end. Transmission losses, system instability and increasing cost in proportion to demand are the main challenges faced in this process. Power flow analysis is required to robustly predict the active / reactive power within the buses, voltage magnitude / phase angles at each bus, cost of transmission and losses well before the practical installation of the power network. Methods/Statistical Analysis: In this paper, we employ power flow analysis using Newton Raphson method and Fast Decoupled method to minimize cost of the electricity and finding optimum active and reactive powers without affecting the voltage regulation. The power flow algorithms are applied for solving the aforementioned load flow problem for ring distribution network of Bahawalpur. We carried out the modeling by obtaining realistic data for constructing bus admittance matrix and specifications of generation units and loads which are connected at the buses. Findings: As a result, optimum flow of power along with the voltage values among different regions of Bahawalpur is obtained. The results from both the algorithms successfully converge and there is an absolute match to validate the accuracy. Novelty: These novel results are of paramount importance since the proposed architecture of Bahawalpur is ring distribution network to replace the existing radial network for improved performance. Furthermore, this research will pave the way for power system planning of Bahawalpur region where all the electrical parameters are known beforehand to design the components according to the requirement. Keywords: Electric power system; voltage magnitude; phase angle; power flow analysis; Newton Raphson method; ring distribution network; active power; reactive power

Conceptual model framework for demand response ancillary services deployed by inter-connected microgrids in West Africa – A Nigerian case study

As a result of the poor electrification rate in many Sub-Saharan countries, several researches have been geared towards the adoption of distributed generation resources (in micro-grids) as a means to ameliorate this menace. For substantial ancillary services rendered, multiple micro-grid operators need to participate in the capacity and energy market. A conceptual framework model is presented in this paper where four distinct microgrids within rural communities are inter-linked and provide ancillary services to one another in the case of a capacity outage in any one of the other microgrids. The Microgrid Ancillary Service Operator (MASO) is in charge of managing the ancillary service which will accept bids from demand response aggregators, and then perform an optimal power flow to allocate capacities (energy resources) to meet demands in a day-ahead or hour-ahead time frame. The techno-economic analysis and distribution network design for one of the micro-grids considered was performed for a typical rural community in a Nigeria which had a residential and commercial load of 551 kWh/day and 23 kW h/day respectively. Results from HOMER showed an optimal system combination of 350 kW solar PV, 150 kW diesel generator, 300 units of Surrette 4KS25 P battery (having a usable nominal capacity of 1368 kW h), and a 100-kW converter. Also, using voltage drop constraints, the analytical design for a 3-bus ring distribution network which comprised a main feeder, and two load buses produced appropriate wiring sizes alongside commensurate resistance and reactance parameters which were within the permissible voltage limits set.

Ring-shaped DC Distribution Network Protection Scheme Research Based-on Voltage Prediction

In this paper, it researches the DC-ring distribution network protection scheme. Firstly, it analyzes the fault characteristics of the voltage source converter (VSC) during the DC line-to-ground. Secondly, it proposes a DC distribution network protection scheme based-on local measurement. The quadratic time-varying function is utilized to predict the line-side voltage in case of failure. The difference between the predicted voltage and the measured voltage on the line side in case of failure is utilized as the primary protective action criterion. Under voltage protection is utilized as backup protection in DC ring distribution network to guarantee safety and stability in case of failure. And the overcurrent protection is utilized as the startup criterion. The additional criteria are added to the further distinction between internal faults and external faults to prevent protection malfunction. The loop DC-distribution network protection scheme simulation based-on real-time digital simulator (RTDS) has verified the feasibility and effectiveness of the proposed scheme.

Design of an Optimal Reticulation System for a Residential Area

The sizing of components in any reticulation scheme usually follows previous experience and trends. This paper develops an algorithm which finds the optimal sizing of cables, transformers and substations to yield an overall optimal reticulation system for a residential area. An optimal system is defined as one which satisfies all the engineering requirements, and also yields a minimum cost over its operating lifetime. Attention is paid to such considerations as the locations of high voltage and medium voltage substations, and of secondary low voltage distribution points, their individual power ratings and voltage levels; a radial or a ring distribution network, aluminium or copper cables, and their routes; load growth and reliability. Several case studies are presented and compared with the cost of an actual practical design based on current conservative practice in South Africa. The results show that the theoretically optimum design could lead to as much as a 25% saving in the lifetime costs of the reticulation scheme.