Phase-Independent Reactive Power Compensation Based on Four-Wire Power Converter in the Presence of Angular Asymmetry between Voltage Vectors

The paper presents the reactive power compensation method that allows for reducing the active power flow even in the presence of angular asymmetry between voltage vectors of the utility grid. Reactive power compensation ensures the reduction of power transmission losses and therefore brings significant economic benefits to electricity consumers. The concept of the alternating current/direct current (AC/DC) converter for prosumer applications operating as a local reactive power compensator has been proposed. The system is driven by a multi-resonant algorithm, allowing for independent control of the reactive power in each phase. The proposed method was validated experimentally by using a prototype of the converter, programmable AC source, and grid impedance model. The method made it possible to cover the reactive power demand without unnecessary active power generation and thus to improve the efficiency of the analyzed prototype. This solution can be implemented particularly in radial grids and non-urban areas.

Consensus-Based Distributed Optimization of Generation Dispatch of Multi-Area AC Systems Interconnected by DC Lines

This paper is dedicated to solving the distributed optimization of generation dispatch of multi-area AC systems interconnected by DC lines, which aims at minimizing the total generation cost while satisfying the power supply demand balance and generation capacity constraints. A novel nodal loss formula which derived from the branch active power flow equation is proposed based on phase angle and impedance to improve the system economy. A distributed algorithm based on consensus is built to solve the generation dispatch problem. It has a great effect on improving convergence effect and rate of the system. The control strategy is used on the structure of multi-area interconnection, which improves the reliability of power supply and guarantee the power quality. The study was conducted using three area AC systems interconnected by DC lines. The simulation results show that the proposed generation dispatch method is reliable in convergence. It provides an effective tool for distributed optimization of generation dispatch of multi-area AC systems interconnected by DC lines.

A minimization model of the power shortage of electric power systems with regard to the restrictions on controlled sections

A steady trend towards the development of electric power systems leads to their continuous enlargement and sophistication. As a result, new ways of their control appear. In this regard, the existing models and complexes for adequacy assessment may work inadequately and ineffectively in terms of the obtained results adequacy. To assess the current state of the existing models and complexes, we reviewed and analyzed the domestic and foreign software and computer systems. In particular, we considered mathematical models of minimizing the power shortage. This work is based on the problem of modifying mathematical models of minimizing the power shortage used in adequacy assessment of the electric power systems of one of the complexes under consideration. As a modification of mathematical models, it is proposed to exclude the existing method of using the line capacities and start use correct accounting for the maximum permissible active power flow in controlled sections. The experimental part reflected in the paper concerns the testing of options for models to minimize the power shortage, as well as the proposed modifications on various systems, including those consisting of three and seven reliability zones with a variable number of controlled sections and power lines included in them. The results of the study have shown that the proposed modifications are efficient and can be used in the future. The authors also obtained the most adequate results in terms of the physical laws of electric power system operation due to the model of minimizing the power shortage with quadratic losses which takes into account the limitations of power transmission over controlled sections.

A Practical GERI-Based Method for Identifying Multiple Erroneous Parameters and Measurements Simultaneously

Even with modern smart metering systems, erroneous measurements of the real and reactive power in the power system are unavoidable. Multiple erroneous parameters and measurements may occur simultaneously in the state estimation of a bulk power system. This paper proposes a gross error reduction index (GERI)-based method as an additional module for existing state estimators in order to identify multiple erroneous parameters and measurements simultaneously. The measurements are acquired from a supervisory control and data acquisition system and mainly include voltage amplitudes, branch current amplitudes, active power flow, and reactive power flow. This method uses a structure consisting of nested two loops. First, gross errors and the GERI indexes are calculated in the inner loop. Second, the GERI indexes are compared and the maximum GERI in each inner loop is associated with the most suspicious parameter or measurement. Third, when the maximum GERI is less than a given threshold in the outer loop, its corresponding erroneous parameter or measurement is identified. Multiple measurement scans are also adopted in order to increase the redundancy of measurements and the observability of parameters. It should be noted that the proposed algorithm can be directly integrated into the Weighted Least Square estimator. Furthermore, using a faster simplified calculation technique with Givens rotations reduces the required computer memory and increases the computation speed. This method has been demonstrated in the IEEE 14-bus test system and several matpower cases. Due to its outstanding practical performance, it is now used at six provincial power control centers in the Eastern Grid of China.

CONGESTION MITIGATION IN DISTRIBUTION NETWORK BY INTEGRATED DISTRIBUTED GENERATIONS FOR IMPROVING VOLTAGE PROFILES AND MINIMIZING THE LOSSES

In electrical power systems, unexpected outage of transmission systems, sudden increase of loads, the exit of generators from service, and equipment failure, leads to a contingency occurring on one or several transmission lines. The loads must be within the specified state and the transmission lines should not exceed the thermal limits. One of the important methods used to alleviate the contingency and reduce the congestion lines by injected a Distributed Generation (DG) within an optimal siting and optimal sizing in the distribution network that achieves improvement of the voltage profile as well as leads to reduce the losses. First, to achieve the best goals in this paper that is determined contingency lines, an index has been used called (Active Power Flow Performance Index) (PIRPF) and an equation called (Line Flow Sensitivity Index) (LFSI) is used for finding the optimum site for Distributed Generation. Second, to determine the optimum size for distributed generators, the Genetic Algorithm (GA) is used. Also, this research was distinguished by choosing new sites and sizes according to the GA to obtain the best desired results. Finally, these methodologies were applied to the IEEE-30 bus ring network using the MATPOWER Version 6.0, 16-Dec-2016 program within MATLAP R2018a environment.

Exploratory Factor Analysis of Distribution Networks Characterization by Metrics of Complex Networks Theory

Distribution networks are responsible for supplying electricity to most consumers, and also are the power system part where the majority of electricity interruptions occurs. These infrastructures are in urban and rural regions and are organized to meet different geographical and operational restrictions and the energy demand. In this study, the use of metrics from complex networks theory to describe the organization of such important systems in topological and electrical perspectives was evaluated. A variety of metrics were extracted from different distribution networks. They were calculated considering topological and active power flow in nominal conditions information. The values obtained were investigated using exploratory factor analysis approach. Results indicated that the metrics can be grouped into three distinct factors, and there is a metric, unrelated to such factors, which describes how the power flow is distributed over the network structure. Considering the importance of such systems and the various possibilities of the operational and topological organization, the knowledge of metrics capable of characterizing, in a systemic perspective, is significant for the analysis of current and future challenges related to energy distribution. This topic and its applications will be furtherexplored in future research.

OPTIMAL POWER FLOW USING STATCOM

— In power system, active power flow is the main concern in order to manage the demand supply. The maximum use of the transmission lines under their stability limit is very much required. Flexible alternating current transmission system (FACTS) device are very much useful to control power system parameters. A STATCOM (STATCOM) is a FACTS device which is able to control active and reactive power with voltage magnitude and phase angle. In this paper, STATCOM is used in a 10 bus system to control the flow of active power under contingency condition. Simulation result shows the effectiveness of the STATCOM in providing the optimal power flow in the power system considered here.

Fixed Transmission Charges Based on the Degree of Network Utilization

The core objective of transmission tariffs is the recovery of costs related to the transport of electricity. A usual component of a tariff is a fixed charge that covers the costs of the network infrastructure. As many customers use the power grid, the rate of this charge should reflect, as closely as possible, the actual costs of supplying energy to the individual consumers. These costs result from which network elements have been used in delivering the electricity, and to what extent these elements have been used. Therefore, the fixed transmission rates should depend on the degree of network utilization. This article investigates definitions of the degree of network utilization based on the active power flow. To calculate the degree of network utilization, the flow of electricity on a branch must be decomposed into the streams flowing to individual customers. For this decomposition, two methods are examined: a power flow tracing method, based on the proportional sharing principle, and an incremental power flow method, based on the superposition principle. The analyzed methodology is applied to a small test system for conceptual discussions, as well as to the transmission network of the Polish power system, as an example of practical application. The results of this study were then compared with the commonly used “postage stamp” method. Finally, several practical aspects related to the potential implementation of the presented methodology are discussed.

SSSC to control Power flow in the Line

FACTS controller is the Power Electronics based static controller which enhance power transfer capability and increase controllability of the power system network. Static Synchronous Series Compensator (SSSC) is VSC based controller which is used in transmission network with the aim of utilization of existing line upto its fullest extent. This paper demonstrates transmission line power flow control with the help of SSSC. A control scheme of SSSC is presented to control active power flow in the line. Increase in the power flow in the line is realized with SSSC operation in capacitive mode of operation and decrease in the power flow is realized with SSSC operated in inductive mode of operation. MATLAB simulation studies are demonstrated to validate the SSSC operation.