Power Compensation In Distribution Networks Research Articles

Dynamic active and reactive power compensation in distribution networks using PV-STATCOMs: A tutorial using the Julia software

This document presents a tutorial regarding the use of PV-STATCOMs for dynamic active and reactive power compensation in AC distribution networks. The main idea is to guide the reader from the classical power flow formulation for AC distribution networks in the complex domain to a multi-period power flow problem using the optimization tools available in the Julia programming software. The use of PV-STATCOMs as dynamic active and reactive power compensation tools allows considering different power factors, i.e., they can work as a PV generation plant with a unitary power factor, as a purely reactive power compensator (capacitive or inductive), or as a dynamic active and reactive power compensator with a variable power factor. The Julia software was selected as a programming environment due to its excellent performance in terms of its programming interface and the use of specialized solvers for nonlinear programming problems in the complex domain, which helps introduce some concepts for the efficient operation of distribution networks while focusing on the mathematical model instead of on the solution technique. Numerical results confirm that the proposed approach, which uses the Ipopt solver, yields excellent numerical solutions in comparison with optimization methodologies recently reported in the scientific literature. A version of the IEEE 33-bus grid adapted for multi-period optimal power flow studies was employed as a test feeder. All numerical results were obtained using Julia, with the help of the JuMP optimization environment and the Ipopt solver.

Optimal Reactive Power Compensation in Distribution Networks with Radial and Meshed Structures Using D-STATCOMs: A Mixed-Integer Convex Approach.

This paper deals with the problem regarding the optimal siting and sizing of distribution static compensators (D-STATCOMs) in electrical distribution networks to minimize the expected total annual operating costs. These costs are associated with the investments made in D-STATCOMs and expected energy losses costs. To represent the electrical behavior of the distribution networks, a power flow formulation is used which includes voltages, currents, and power as variables via incidence matrix representation. This formulation generates a mixed-integer nonlinear programming (MINLP) model that accurately represents the studied problem. However, in light of the complexities involved in solving this MINLP model efficiently, this research proposes a mixed-integer convex reformulation. Numerical results regarding the final annual operating costs of the network demonstrate that the proposed mixed-integer convex model is efficient for selecting and locating D-STATCOMs in distribution networks, with the main advantage that it is applicable to radial and meshed distribution grid configurations. A comparative analysis with respect to metaheuristic optimizers and convex approximations confirms the robustness of the proposed formulation. All numerical validations were conducted in the MATLAB programming environment with our own scripts (in the case of metaheuristics) and the CVX convex disciplined tool via the Gurobi solver. In addition, the exact MINLP model is solved using the GAMS software.

A Novel Integrated Method for Harmonic Suppression and Reactive Power Compensation in Distribution Network

Aiming at the serious harmonic pollution and the low power factor in the distribution network of industrial enterprises, this paper develops an integrated method for harmonic suppression and reactive power compensation suitable for the distribution network of industrial enterprises. The integrated method realizes the dual functions of harmonic filtering and reactive power compensation, and filters out the harmonic current to get a symmetrical current waveform while ensuring safe operation of the power compensator. In addition, it solves the problems of high harmonic content, small power factor in the distribution network, and device burnout caused by direct input of reactive power compensator. The main contributions of this paper are as follows: (1) According to the demand for the integration of harmonic suppression and reactive power compensation, the steps of integrated method for harmonic suppression and reactive power compensationare proposed, and then the methods for harmonic filtering and reactive power compensation are investigated; (2) a method for designing the capacity of a filter capacitor and the rated parameter of an electromagnetic coupling reactance converter is proposed, and an optimization simulation system is constructed to design the parameters of the filter; (3) a simulation system is developed, followed by parameter design and simulation analysis of harmonic filtering subsystem (HFSS), reactive power compensation subsystem (RPCSS) and the integrated system of harmonic suppression and reactive power compensation. Simulation results verify that the HFSS is put into operation first and then switched off later to ensure the normal operation of other equipment in the distribution network. After the treatment, the power factor, harmonic current content and total distortion rate all meet the national standards. The integrated method can dynamically track harmonics and reactive power changes, filter out harmonics, improve power factor and the symmetry level of the power source, and ensure the normal operation of other equipment in the distribution network. The research results lay a certain theoretical and technical foundation for the harmonic filtering and reactive power compensation theory, technology and its device innovation to achieve effective suppression of power harmonics and reactive power compensation.

Genetic-Convex Model for Dynamic Reactive Power Compensation in Distribution Networks Using D-STATCOMs

This paper proposes a new hybrid master–slave optimization approach to address the problem of the optimal placement and sizing of distribution static compensators (D-STATCOMs) in electrical distribution grids. The optimal location of the D-STATCOMs is identified by implementing the classical and well-known Chu and Beasley genetic algorithm, which employs an integer codification to select the nodes where these will be installed. To determine the optimal sizes of the D-STATCOMs, a second-order cone programming reformulation of the optimal power flow problem is employed with the aim of minimizing the total costs of the daily energy losses. The objective function considered in this study is the minimization of the annual operative costs associated with energy losses and installation investments in D-STATCOMs. This objective function is subject to classical power balance constraints and device capabilities, which generates a mixed-integer nonlinear programming model that is solved with the proposed genetic-convex strategy. Numerical validations in the 33-node test feeder with radial configuration show the proposed genetic-convex model’s effectiveness to minimize the annual operative costs of the grid when compared with the optimization solvers available in GAMS software.

A Second-Order Cone Programming Reformulation of the Economic Dispatch Problem of BESS for Apparent Power Compensation in AC Distribution Networks

The problem associated with economic dispatch of battery energy storage systems (BESSs) in alternating current (AC) distribution networks is addressed in this paper through convex optimization. The exact nonlinear programming model that represents the economic dispatch problem is transformed into a second-order cone programming (SOCP) model, thereby guaranteeing the global optimal solution-finding due to the conic (i.e., convex) structure of the solution space. The proposed economic dispatch model of the BESS considers the possibility of injecting/absorbing active and reactive power, in turn, enabling the dynamical apparent power compensation in the distribution network. A basic control design based on passivity-based control theory is introduced in order to show the possibility of independently controlling both powers (i.e., active and reactive). The computational validation of the proposed SOCP model in a medium-voltage test feeder composed of 33 nodes demonstrates the efficiency of convex optimization for solving nonlinear programming models via conic approximations. All numerical validations have been carried out in the general algebraic modeling system.

Dynamic active and reactive power compensation in distribution networks with batteries: A day-ahead economic dispatch approach

This paper focuses on the problems of optimal operation of battery energy storage systems (BESSs) in distributed networks from a nonlinear programming (NLP) point of view. This proposal contains the active and reactive power capabilities of the voltage source converters that interface with the BESS independently, which implies that the BESSs have the possibility to work as dynamic energy compensators over all the four quadrants. Two radial distribution networks have been used to validate the proposed NLP model. This model has been arrived at by using the general algebraic modeling system (GAMS) optimization package. Artificial neural networks (ANN) are also employed for short-term forecasting of renewable generation based on wind and photo-voltaic sources. Numerical results show that the inclusion of reactive power capabilities of batteries reduces the daily operational cost of the network as compared to the classical unity power factor operation approach. All the simulations are made considering Colombian utility typical curves.

LVCI approach for optimal allocation of distributed generations and capacitor banks in distribution grids based on moth–flame optimization algorithm

In recent years, due to growth in electricity demand, distribution networks suffer from increased power losses, decreased voltage levels, and increased power quality problems. The distributed generations (DGs) and shunt capacitor banks (SCBs) are considered the convenient sources of active and reactive power compensation in distribution networks, respectively. Moreover, the optimum allocation of DGs and SCBs plays a sufficient role in improving voltage profile and voltage stability that lead to ameliorate power quality and minimize the system power losses. In this respect, this article provides a novel efficient and vigorous moth–flame optimization (MFO) algorithm for solving the optimization problem of DGs and SCBs allocation. Furthermore, a loss–voltage–cost index (LVCI) approach has been incorporated into the proposed optimization methodology as an effective objective function to enhance the voltage profile and minimize the system power losses and the total annual operating cost. Moreover, the proposed scheme is implemented in two stages. In the first stage, the most candidate buses for installing DGs and SCBs are evaluated using loss sensitivity factors (LSFs). In the second stage, the MFO optimization algorithm is implemented to estimate the optimal placement of DGs and SCBs besides their sizing from the nominated buses based on LVCI as the main objective function. The suggested scheme has been tested on 33-bus and 69-bus IEEE standard radial distribution networks with different load levels. Furthermore, it is applied on a practical case study of Moscow region network that consists of 111-bus radial distribution network under different load levels. To insure the validation and accuracy of the proposed algorithm, the acquired results have been compared with other methods and techniques. The numerical results proved that the suggested optimization scheme has notability with high accuracy to estimate the optimal solution of DGs and SCBs allocation for minimizing the system power losses, enhancing the voltage profile and maximizing the net savings as compared to other techniques.

Reactive power compensation in distribution networks of mining enterprises

Large electricity consumers – mining companies – along with active power consumed reactive power, creating network flows. The issues of compensation of reactive power and rational placing of the compensating devices are becoming highly relevant in the light of energy saving policies. Compensation is particularly important when optimization of voltage and power consumption in order to reduce active losses and improve power quality. Effective action for reduction of losses in electric networks is installation of devices of reactive power compensation (RPC). In the analysis of methods of calculation of optimal power compensating devices, and location were taken into account the specificity of mining enterprises, namely the separation of electrical networks underground and surface. The objective function formulated on the basis of annual reduced costs and identified system limitation, when considered in the objective function. The analysis of the objective function showed that it separaely and the problem can be solved by methods of discrete programming.

EFEKTYWNOŚĆ KOMPENSACJI MOCY BIERNEJ W ELEKTROENERGETYCZNYCH SIECIACH DYSTRYBUCYJNYCH

Reactive power is essential to the work of many AC devices, but the generation and transmission causes many negative effects. One way to counteract the negative effects of reactive power transmission reactive power compensation involving the installation of additional reactive power sources in selected points in the network. The paper presents a method of calculating the limitation of power and energy loss, and the assessment of the economic efficiency of reactive power compensation. Theoretical considerations are illustrated with calculation examples of the effectiveness of the most commonly methods of reactive power compensation used in the Polish distribution networks. The paper also presents conclusions from the analysis of the results and proposed solutions to improve the economic efficiency of reactive power compensation in distribution networks.

Optimal Planning on Reactive Power Compensation of Distribution Network Based on Back/Forward Sweep Method and Tabu Search Algorithm

This paper proposes the optimization method on reactive power compensation of distribution network. The objective is that total loss difference between before being compensated and after should get maximum. The method adopts back/forward sweep method for calculating power flow to obtain total active network loss. Then global neighborhood searching strategy and aspiration criterion for fixed parallel capacitor are established by tabu search algorithm. The optimal installation location and compensation capacity of fixed parallel capacitor are determined. Optimizing simulation on a 34 nodes distribution system is realized, and optimal planning scheme is obtained. Results show that the proposed method is feasible and effective in optimal planning on reactive power compensation of distribution network.

Unified power quality conditioner allocation for reactive power compensation of radial distribution networks

This paper presents an investigative study on unified power quality conditioner (UPQC) allocation for reactive power compensation of radial distribution networks. An UPQC consists of a series and a shunt inverter. The UPQC model based on phase angle control (UPQC-PAC) is used. In UPQC-PAC, the series inverter injects a voltage with controllable phase angle in such a way that the voltage magnitude at load end remains unchanged. Owing to the phase angle shift, the series inverter participates in load reactive power compensation along with the shunt inverter during healthy operating condition. The UPQC-PAC model is suitably modified so as to provide the reactive power compensation of a distribution network. The impact of the UPQC-PAC allocation is studied by placing it at each bus of a network, except the substation bus, one at a time. A load flow algorithm including the UPQC-PAC model is devised and used in the determination of its optimal location in a network. The simulation study shows that the optimal allocation of UPQC-PAC results in significant amount of power loss reduction, under voltage mitigation, and enhancement of voltage stability margin. Better power loss and bus voltage are obtained with UPQC-PAC compared with some existing reactive power compensation approaches.

Reactive power compensation in distribution networks using cuckoo search algorithm

This manuscript presents a cuckoo search optimisation-based approach to allocate static shunt capacitors along radial distribution networks. The objective function is adapted to reduce the system peak losses and to improve the system voltage profile. Higher potential buses for capacitor placement are initially identified using power loss index. The proposed approach identifies optimal sizing and placement and takes the final decision for optimum location. The overall accuracy and reliability of the approach have been validated and tested on radial distribution systems with differing topologies and of varying sizes and complexities. The results are compared with those obtained using recent heuristic methods and show that the proposed approach is capable of producing high-quality solutions with good performance of convergence.

Reactive Power Compensation of Distribution Network Based on Immune and Particle Swarm Optimization Algorithm

The reactive power compensation optimization in distribution network has the important meaning in maintaining system voltage stability, decreasing network loss and reducing operation costs. In order to meet factual conditions, we assume the system operates in minimum, normal and maximum three load modes and the objective function of problem includes the costs of power loss and the dynamic reactive power compensation devices allocated. In this paper we use Artificial Immune Algorithm(AIA) and Particle Swarm Optimization Algorithm(PSO) to determine compensate nodes and use the back/forward sweep algorithm calculate load flows. After applied into 28-nodes system, the result demonstrates the method is feasible and effective.

Reactive Power Compensation of Distribution Network Based on Bacterial Colony Chemotaxis Algorithm

Reactive power compensation of distribution network is an important method to improve power quality and voltage stability, while reducing the power loss of the distribution network. In this paper the objective function is built to minimize all the costs which include power loss costs and investment of the dynamic reactive power compensation device divided into each year. The actual operation of the distribution network is simulated considering light, normal and heavy load operation conditions. Bacterial colony chemotaxis (BCC) algorithm is used to determine which nodes to install the compensation devices. The calculation of reactive power compensation is done with the back/forward sweep algorithm adapting to the radial distribution system. In order to compensate three different load conditions separately, the fixed part and the switching part of the dynamic reactive power compensation device are used. This method applies to 28-node system, the result demonstrates that the method is feasible and effective.