Control Of Capacitor Banks Research Articles

Optimal strategy to reduce energy waste in an electricity distribution network through direct/indirect bulk load control

In recent decades, the ever-increasing demand for electricity in large cities is leading the electricity distribution network (EDN) to an operational state of fatigue, especially at peak load times. In this context, load congestion, technical losses, and voltage deviations across the EDN can contribute to the high waste of electricity as well as to the worsening of the supply service. To face this problem, this paper proposes a mixed integer linear programming (MILP) model that aims to reshape the demand profile (i.e., load reduction in peak periods without load rebound in the remaining periods of the day) of total consumers while the voltage deviations and technical losses are minimized. In the proposed model, the demand profile reshaping is carried out through direct (DC) and indirect (IC) bulk control of residential, commercial, and industrial loads, while the load factor (LF), i.e., indicator related to the efficient use of electricity, is improved. Due to the scheduling of these loads at certain times of the day, the occurrence of voltage deviations and technical losses can be mitigated by the efficient control of capacitor banks (CBs). To corroborate the applicability of the proposed MILP model, the 33-node IEEE test system was used. The results show the technical and economic gains for the distribution company (DISCO) and the total number of consumers.

New solutions for controlled compensating devices

The article presents material, which is based on the results of the analysis of literature sources on automatic devices for regulating reactive power in power supply systems. In addition, this article provides information regarding the operability of the developed circuits of contactless devices and verification of the experimental study of the operation of installations with their use. Also presented is material about an experimental study of a contactless switching device for automatic power control of capacitor banks in various operating modes. A measuring device with programmed control “Fluke” was used to record and process experimental data of non-contact devices for regulating the power of capacitor banks. The results of experimental studies of a new device for automatic power control of capacitor banks, it can be stated that it fully meets the requirements.

Development and experimental study of circuits of contactless device for automation of compensation of reactive power of capacitor batteries

This article presents material based on the results of the analysis of literature sources on automatic devices for regulating reactive power in power supply systems. The operating mode of the compensating devices is determined taking into account the permissible voltage deviations at the terminals of the electric power receivers. Voltage, load current, reactive power directions, power factor, phase angle between the supply voltage and load current, and time can be used as control parameters. In addition, the article provides information regarding the performance of the developed circuits of contactless devices and verification of the experimental study of the operation of installations with their use. Also presented is material on the experimental study of a prototype of a contactless switching device for automatic power control of capacitor banks in various operating modes. Summarizing the results of experimental studies of a new device for automatic power control of capacitor banks, it can be stated that it fully meets the requirements for such devices and can ensure reliable operation of the power supply network with an appropriate power factor.

Capacitor bank controller using artificial neural network with closed-loop system

The problem of power factor in the industry is critical. This is due to the issue of low power factor that can make the vulnerability of industrial equipment damaged. This problem has been resolved in various ways, one of which is the Automatic Power Factor Correction, with the most popular device called capacitor bank. There are also many methods used, but several methods require certain calculations so the system can adapt to the new plant. In this study, researchers proposed a capacitor bank control system that can adapt to plants with different capacitor values without using any calculations by using an Artificial Neural Network with a closed-loop controller. The system is simulated using Simulink Matlab to know the performance with two testing scenarios. The first is changing the value of the power factor on the system and changing the value of the capacitor power at each bank, the second comparing it with the conventional methods. The results show that the system has been able to adapt to different capacitor power values and has a better performance than the conventional method in power factor oscillation due to the extreme power factor interference

Optimal Control and Operation of Fully Automated Distribution Networks Using Improved Tunicate Swarm Intelligent Algorithm

Simultaneous control and operation of Capacitor Banks (CBs) and Distributed Generators (DGs) with Distribution Network Reconfiguration (DNR) is the most important modern trend for distribution systems performance enhancement. The complexity and variety of the control variables of this problem represent a challenge for distribution systems planners and operators as well as interested researchers. Optimal solution can provides quantitative as well as qualitative power service to satisfy consumers’ satisfaction and reduces dissipated energy. Furthermore, performance enhancement of distribution systems is very vital where improving their performance directly affects the performance of transmission and generation systems. For solving the considered problem, an improved Tunicate Swarm Algorithm (ITSA), which imitates the swarming behaviors of the marine tunicates and their jet propulsions during its navigation and foraging procedure, is proposed. In ITSA, Levy flight distributions are emerged in the traditional Tunicate Swarm Algorithm (TSA), which improves the diversification searching abilities of the TSA and consequently avoids the stagnation possibilities. The proposed ITSA is applied and tested for optimal DNR simultaneously with optimal control of the switched CBs and dispatchable DGs taking into account daily load variations. The ITSA is compared with other techniques on the standard 33-bus, 69-bus and the large-scale 119-bus distribution systems considering different automation scenarios of the distribution systems. The simulation results reveal that significant enhancement in distribution system performance is obtained through the application of the proposed automation process using the ITSA. ITSA can efficiently search for the optimal solutions of the problem and outperforms the other existing algorithms in the literatures.

A dynamic method for feeder reconfiguration and capacitor switching in smart distribution systems

In distribution systems, feeder reconfiguration (FR) can lead to loss reduction, reliability improvement and some other economic savings. These advantages can be intensified by proper control and switching of Capacitor Banks (CBs). In this paper, using Ant Colony Optimization (ACO) technique, a novel method is proposed for simultaneous dynamic scheduling of FR and CB switching in the presence of DG units having uncertain and variant generations over time. This method is applicable to both smart and classic distribution systems. While for the latter, state estimation method should be used to estimate the loads at different buses by employing a limited number of measurements. The objective of this method is to minimize the total operational cost of the grid, including the cost of power purchase from the sub-transmission substation, cost of customer interruption penalties, Transformers Loss of Life (TLoL) expenses, and the switching costs (CBs and disconnecting switches). To perform this study, the planning period is divided into several intervals for each of them the network topology and CBs reactive power are determined to satisfy the objective function. Additionally, due to the curse of dimensionality, a Case Reduction Technique (CRT) is proposed in order to decrease the computational burden of the proposed method. Finally, the efficiency of the proposed method is verified through its application on the IEEE 118-bus distribution test system, and evaluating its economic and operational characteristics.

An ant colony system based control of shunt capacitor banks for bulk electricity consumers

The present work focuses on the formulation of an optimization algorithm based on Ant Colony Search (ACS) technique operational from a Blackfin DSP microcontroller platform. This intelligent algorithm enables switching of appropriate Shunt Capacitor Banks (SCBs) in installations of bulk consumers of electricity to improve their power factor. The application is mainly targeted on cold storages, rolling mills, traction substation and steel plants in India, where SCBs are installed over a long period in an unplanned manner. Unawareness of the impact of energy savings coupled with the fiscal incapability of these users make them unable to install costly power electronic devices for p.f. control ACS based embedded controller is sensitive to unpredictable load changes and selective capacitors switching cause optimal VAR control with minimum stress to the system. Employing the distributed computational model based on ACS becomes an ideal tool for the combinatorial optimization problem to select a best combination within a bank of varying sizes and varying status signifying dynamically changing search space. This low cost device will reduce the penalty billing of consumers by improving the p.f. and improved metered reading. The use of this device will lead to permeation of technology to the strata which needs it most making energy management possible without any human intervention.

FUZZY ALGORITHM TO CONTROL REACTIVE POWER FLOW IN ELECTRIC NETWORK WITH NONLINEAR LOADS

One of the important problems of efficient function of electric networks containing load nodes of nonlinear character of power consumption is reactive power compensation and maintaining voltage quality in a grid. The commonly used methods for compensation of harmonic currents by filtering devices make it possible to solve the problem in a narrow band of variation of current of a nonlinear load. In the reality stochastic character of power consumption of nonlinear load reveals itself in appropriate changes in harmonic components of voltage and their share in total load current. This could considerably change the magnitude and direction of reactive power flow in a grid and impair the existing processes of reactive power control. The scheme and the algorithm of control of capacitor banks in networks with non-linear load that are based on the use of fuzzy logic software are presented in the article. The results of model experiments analysis of the modes of the harmonic of the power flows on behalf of the 14-nodal scheme recommended by IEEE as well as the schemes of a real grid with powerful traction substation are presented. The mentioned results demonstrate that when harmonic components of voltages exceed normative magnitudes, the use of the proposed algorithm eliminates additional loading on the capacitor banks with higher harmonic currents whereas the control procedure acquires quality, the number of commutations is being reduced, the capacitor battery functions longer and the probability of its malfunction decreases.

Economic Evaluation of Distribution System Smart Grid Investments

This article investigates the economic benefits of smart grid automation investments. A system consisting of 7 substations and 14 feeders is used in the evaluation. Here benefits that can be quantified in terms of dollar savings are considered, termed “hard dollar” benefits. Smart grid investment evaluations to be considered include investments in improved efficiency, more cost effective use of existing system capacity with automated switches, and coordinated control of capacitor banks and voltage regulators. These smart grid evaluations are sequentially ordered, resulting in a series of incremental hard dollar benefits. Hard dollar benefits come from improved efficiency, delaying large capital equipment investments, shortened storm restoration times, and reduced customer energy use. Analyses used in the evaluation involve hourly power flow analysis over multiple years and Monte Carlo simulations of switching operations during storms using a reconfiguration for a restoration algorithm. The economic analysis uses the time-varying value of the locational marginal price. Algorithms used include reconfiguration for restoration involving either manual or automated switches and coordinated control involving two modes of control. Field validations of phase balancing and capacitor design results are presented. The evaluation shows that investments in automation can improve performance while simultaneously lowering costs.

Priority- and Delay-Aware Medium Access for Wireless Sensor Networks in the Smart Grid

Monitoring smart-grid assets in a timely manner is highly desired for emerging smart-grid applications such as transformer monitoring, capacitor bank control, plug-in hybrid-electric-vehicle load management, and power quality assessment. Wireless sensor and actor networks (WSANs) are anticipated to be widely utilized in a wide range of smart-grid applications due to their numerous advantages along with their successful adoption in various critical areas including military and health. For resource-constrained WSANs, transmitting delay-critical data from smart-grid assets calls for data prioritization and delay responsiveness. In this paper, we introduce two medium-access approaches, namely, delay-responsive cross-layer (DRX) data transmission and fair and delay-aware cross-layer (FDRX) data transmission, which aim to address the delay and service requirements of smart grids. DRX is based on delay-estimation and data-prioritization steps that are performed by the application layer, in addition to the MAC layer parameters responding to the delay requirements of the smart-grid application and the network condition. On the other hand, FDRX incorporates fairness into DRX by preventing a few nodes from dominating the communication channel. We provide a comprehensive performance evaluation of those approaches. We show that DRX reduces the end-to-end delay while FDRX has lower collision rate compared with DRX. We outline the tradeoffs regarding these approaches and draw future research directions for robust communication protocols for smart-grid monitoring applications.

POWER FACTOR CORRECTION OF 6.6KV DISTRIBUTION LINE IN LC11 RMHS DEPARTMENT, JSW STEEL

This paper discusses the design, implementation and analysis of a three phase (6.6kV, 50Hz) capacitor bank controller unit. Power factor correction using capacitor banks reduces reactive power consumption which will lead to minimization of losses and at the same time increases the electrical system’s efficiency. Most of the industrial installations have large electrical loads which are inductive in nature, which results in a lagging power factor. Power factor is the value of a system that reflects how much power is being borrowed from the power company for the system. Many power companies regulate industrial power factors to make sure that they do not fall below a certain level and charge the customer more on their utility bills if the power factor falls below a certain level. Power factor correction serves to correct low power factors by reducing the phase difference between the current and voltage at the distribution point for a company.In case of rapidly varying and scattered load it becomes difficult to maintain a high power factor by manually switching on/off capacitors in proportion to variation of load. Current transformer is used to measure the load current for sampling purposes. The most common way to correct the power factor is to switch capacitor banks at the source to generate reactive power. This work is to make a system that will switch capacitor banks when the power factor drops below a certain point to avoid power company charges.PLC is used to control of switching on/off capacitor bank to improve power factor.

One approach for reactive power control of capacitor banks in distribution and industrial networks

This paper presents an efficient solution for reactive power control of capacitor bank using changes in reactance of connected reactor. This solution ensures smooth control of reactive power of capacitor banks as important operational characteristic for maintaining the quality of supply. The proposed method works for a wide-range of reactive power variations in the system and is capable of injecting or absorbing reactive power when necessary. This control method can be successfully used in distribution and industrial networks where many loads vary their demand for reactive power. Other applications of this method are voltage regulation, power-factor correction and reactive power compensation. The effectiveness of the proposed method is demonstrated through the case studies in order to prove its feasibility for improvement of voltage profile and reduction of power losses.

Minimum loss operation of distribution networks with photovoltaic generation

The proliferation of photovoltaic generation in distribution networks requires assessing the control schemes that achieve minimum loss operation without requiring excessive switching of conventional equipment, for instance capacitor banks and network reconfiguration devices. Inverters associated with photovoltaic generation are traditionally operated at unity power factor; however, there is a potential to make use of their capacity to supply or absorb reactive power. The control of capacitor banks and line switches which is done on a slow time scale can be coordinated with the fast control of inverters through a multi-period optimal power flow formulation. This study shows that such a formulation can be cast as a mixed-integer linear program, whose minimum energy loss solution is guaranteed to be globally optimal. Numerical results on a distribution network with different variation patterns of load and photovoltaic generation demonstrate that the method is effective in establishing the trade-off between different combinations of minimum energy loss control schemes.

Distributed Volt/VAr Control by PV Inverters

A major technical obstacle for rooftop photovoltaics (PV) integration into existing distribution systems is the voltage rise due to the reverse power flow from the distributed PV sources. This paper describes the implementation of a voltage control loop within PV inverters that maintains the voltage within acceptable bounds by absorbing or supplying reactive power. In principle, this can be considered to be a form of distributed Volt/VAr control, which is conventionally performed by coordinated control of capacitor banks and transformer tap changers. Comprehensive simulation studies on detailed feeder models are used to demonstrate that the proposed control scheme will mitigate voltage rises.

Restoration strategy for secondary power network with grey relational analysis

An operational strategy for secondary power system restoration using grey relational analysis (GRA) is presented. The restoration scheme can be divided into three steps involving fault section determination, recovering process and voltage correction process. Three GRAs are incorporated to design the overall restoration scheme. The first GRA uses the network-switching status to identify the fault. The second GRA combines the switching states and load levels for network recovery. The third GRA uses capacitor bank control (CBC) to support bus voltages. Optimal power flow (OPF) is also used to verify the proposed scheme by off-line analysis to confirm a secure overall network operation including load–power balance, power generation limits, voltage limits and power flow limits. Computer simulations were conducted with an IEEE 30-bus power system to show the effectiveness of the proposed restoration scheme.

Voltage Regulation and Power Losses Minimization in Automated Distribution Networks by an Evolutionary Multiobjective Approach

In this paper, the problem of voltage regulation and power losses minimization for automated distribution systems is dealt with. The classical formulation of the problem of optimal control of shunt capacitor banks and Under Load Tap Changers located at HV/MV substations has been coupled with the optimal control of tie-switches and capacitor banks on the feeders of a large radially operated meshed distribution system with the aim of attaining minimum power losses and the flattening of the voltage profile. The considered formulation requires the optimization of two different objectives; therefore the use of adequate multiobjective heuristic optimization methods is needed. The heuristic strategy used for the optimization is based on fuzzy sets theory. After a brief description of the general problem of optimal control of voltage and power losses in automated distribution networks, the most recent papers on the topic are reported and commented. Then the problem formulation and the solution algorithm are described in detail. Finally, numerical results on a large distribution system demonstrate that the proposed formulation and approach are effective and feasible for finding an optimal generalized dispatching schedule.

A new formulation of the optimal compensation and reconfiguration problem including minimum load nodes unavailability for automated distribution networks

This paper deals with a new formulation of the optimal operation of electrical distribution networks problem in regular working state. In the new deregulated energy market providing reliable and economical service to customers is a primary task. The multiobjective formulation of the reconfiguration and compensation problem used in this paper considers as a primary object also the minimisation of the load nodes unavailability (UA) expressed in probabilistic terms. Therefore, the objectives to be attained through the optimisation strategy are: minimal power losses operation, minimum UA of the load nodes, load balancing among the HV/MV transformers, and voltage profile regularisation. The application carried out uses an evolutionary algorithm and a particular normalisation technique for the multiple objectives formulation. In the considered automated network, the remote control of capacitor banks and tie‐switches is possible and their layout is the optimisation variable. After a brief description of the optimal reconfiguration and compensation problem for automated distribution networks, the most recent papers on the topic are reported and commented. Then the problem formulation and the solution algorithm are described in detail. Finally, the test results on a large MV distribution network are reported and discussed.

Neural Networks for Combined Control of Capacitor Banks and Voltage Regulators in Distribution Systems

A neural network for controlling shunt capacitor banks and feeder voltage regulators in electric distribution systems is presented. The objective of the neural controller is to minimize total I/sup 2/R losses and maintain all bus voltages within standard limits. The performance of the neural network for different input selections and training data is discussed and compared. Two different input selections are tried, one using the previous control states of the capacitors and regulator along with measured line flows and voltage which is equivalent to having feedback and the other with measured line flows and voltage without previous control settings. The results indicate that the neural net controller with feedback can outperform the one without. Also, proper selection of a training data set that adequately covers the operating space of the distribution system is important for achieving satisfactory performance with the neural controller. The neural controller is tested on a radially configured distribution system with 30 buses, 5 switchable capacitor banks and a nine tap line regulators to demonstrate the performance characteristics associated with these principles. Monte Carlo simulations show that a carefully designed and relatively compact neural network with a small but carefully developed training set can perform quite well under slight and extreme variation of loading conditions.

Neural networks for combined control of capacitor banks and voltage regulators in distribution systems

A neural network for controlling shunt capacitor banks and feeder voltage regulators in electric distribution systems is presented. The objective of the neural controller is to minimize total I/sup 2/R losses and maintain all bus voltages within standard limits. The performance of the neural network for different input selections and training data is discussed and compared. Two different input selections are tried, one using the previous control states of the capacitors and regulator along with measured line flows and voltage which is equivalent to having feedback and the other with measured line flows and voltage without previous control settings. The results indicate that the neural net controller with feedback can outperform the one without. Also, proper selection of a training data set that adequately covers the operating space of the distribution system is important for achieving satisfactory performance with the neural controller. The neural controller is tested on a radially configured distribution system with 30 buses, 5 switchable capacitor banks and a nine tap line regulators to demonstrate the performance characteristics associated with these principles. Monte Carlo simulations show that a carefully designed and relatively compact neural network with a small but carefully developed training set can perform quite well under slight and extreme variation of loading conditions.

Real time T&D applications at Virginia Power

Advances in the automation of the transmission and distribution (T&D) system at Virginia Power in the 1980s are described. Programs such as supervisory control and data acquisition (SCADA) and load management using a two-way automatic control system (TWACS) have reduced system losses and increased the reliability of service to the customer. Inhouse support of SCADA software has provided flexibility to meet the changing operating conditions. The discussion covers CAPCON, a capacitor bank control program which was the first process control application written for the SCADA II machines; automation of load tap changer controls; control sequences, particularly for voltage reduction and emergency load curtailment; emergency isolation of network grids; and TWACS.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>