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Active power loss of transmission lines in a distribution system has been a frequent concern for a great number of researchers. Various approaches have been proposed to minimize active power loss. In this research, two approaches, optimal placement and sizing of distributed generation (DG) and shunt capacitor, are used to reduce the active power loss in a distribution system. Particle Swarm Optimization (PSO) and Newton-Raphson method are integrated to find the optimal location and size of DG and shunt capacitor while maintaining operation constraints. The proposed technique is tested on a radial distribution system based on Vava’u island’s distribution system in Tonga. The algorithm is implemented in MATLAB and the results are verified with DIgSILENT PowerFactory. Three case scenarios of the optimal placement and sizing, namely: DG only, shunt capacitor only, and DG & shunt capacitor, were tested. The technique successfully found the optimal location and size of DG and shunt capacitor in three case scenarios and further found the most optimal solution among these three cases.

This paper presents an efficient hybrid method to solve the allocation problem of capacitor banks in radial distribution system (RDS). The presented method is based on two-stages. In the first stage, the most candidate locations for incorporating of shunt capacitors are determined using a loss sensitivity factor (LSF) and in second stage, the moth-flame optimization (MFO) algorithm is employed to determine the optimal sizes and locations of capacitors for to minimizing the energy cost. The presented method is validated using the standard 69-bus RDS under light, nominal and peak load levels. The obtained results using the proposed hybrid method are compared with those obtained from different reported optimization techniques in literature. Numerical results show the superiority of the proposed method over the other reported techniques for minimizing the cost in radial distribution system.

This paper presents a new optimization technique called Ant-lion optimization (ALO) in order to determine the optimal sitting and size of shunt capacitors in radial distribution systems (RDS). The objective functions are suggested to minimize the power loss and enhance the voltage profile individually or simultaneously. Standard IEEE 33-bus and 69-bus test system are used to validate the effectiveness and superiority of the new optimization algorithm compared with different well-known techniques. The obtained results demonstrate that both of power loss and voltage deviation can be minimized significantly after demining the optimal allocation of shunt capacitor banks using ALO algorithm.

The application of power electronics in HVDC systems inevitably lead to various power quality problems, such as harmonic pollution, reactive loss and commutation failure, etc. To solve these issues, this paper proposes a novel shunt capacitor commutated converters (SCCC) to figure them out. The topology can be described as follows, the shunt capacitors are installed at the altering current (ac) bus between the valve winding of converter transformers and the converters, it can replaces the conventional HVDC system with line commutated converters (LCC) where the harmonic filters and shunt capacitors are installed at the ac grid side. Firstly, the characteristics and operating mechanism of the new HVDC system with SCCC are analyzed, and then, the harmonic equivalent model is established. Moreover, the mathematical model for the SCCC-HVDC system is presented. The feasibility of the proposed new topology is validated by simulation results. It manifests that the shunt capacitors not only greatly absorbs the high-order harmonic but also eliminates the commutation angle μ absolutely, hence, the commutation ability can be enhanced greatly. Besides, it also presents good filtering and reactive power compensating performances to public networks.

The increasing penetration of electric vehicles (EVs) will bring great challenges to the secure and economic operation of distribution networks. On the other hand, coordinated charging of EVs can alleviate the adverse impacts of charging loads and even increase the efficiency of distribution network operation. This paper aims at optimally scheduling the daily charging of EVs and the daily on/off switching of shunt capacitors to minimize the total active power losses. We formulate a mixed integer second-order cone programming (MI- SOCP) model for this scheduling problem considering the distribution network security constraints. Case study results show that coordinated charging of EVs with reactive power optimization can effectively reduce the active power losses and improve the nodal voltage profiles.

Harmonic resonance has become an important concern for the application of shunt capacitors in recent years. A potential solution to address this challenge is to convert a shunt capacitor into a passive filter. This paper presents design methods to configure a shunt capacitor as a C-type filter or a third-order high-pass filter with guaranteed resonance-free performance. The concept of resonance-free condition is first introduced in this paper. It is then used to develop filter design methods that always meet the resonance-free condition. The two filter configurations are also compared. It was found that the third-order high-pass filter has more advantages than the C-type filter. Another useful finding of this work is that the filter parameters, as determined using the proposed design methods, are independent of the system conditions. As a result, a lookup table for the filter parameters has been created to facilitate immediate use by the industry.

In this paper, a novel analytical technique is proposed to determine the optimal size and location of shunt capacitor units in radial distribution systems. An objective function is formulated to reduce real power loss, to improve the voltage profile and to increase annual cost savings. A new constant, the Loss Sensitivity Constant (LSC), is proposed here. The value of LSC decides the location and size of candidate buses. The technique is demonstrated on an IEEE-33 bus system at different load levels and the 130-bus distribution system of Jamawa Ramgarh village, Jaipur city. The obtained results are compared with the latest optimization techniques to show the effectiveness and robustness of the proposed technique.

This paper presents an analysis of the reactive power and voltage stability of the Northern region of Bangladesh Power System Network (BPSN) in EDSA Paladin Design Base Software. In order to prevent unacceptable voltage collapses and to reduce losses to ensure sufficient reactive power during normal and emergency conditions, voltage level at different points has been analyzed and determining those nodes which are allowing to exceed the permitted range or weak points in BPSN through simulation results. Handling this situation, the voltage and reactive power control in distribution system can be properly controlled by coordinating transformer tap changing and shunt capacitors. Simulation results show that by providing shunt capacitor among the buses to the collapse point results in improved voltage stability within positive consequence limit as an acceptable voltage level in the system.

Power system stability is a serious concern of power system engineers and utilities especially after the recent occurrences of major events of black outs. Power factor improvement devices such as capacitors, optimally placed in series or shunt in any given network can improve its voltage as well as angular stability. Thermal limits of lines can be observed as the system is visible at all times through synchrophasor data. For this, New England 39 Bus system is used as test system. The simulations are carried out on PSSE. Compensation on selective buses is carried out using sensitivity analysis.

At present the use of distributed generation (DG) units and shunt capacitors simultaneously in radial distribution system (RDS) is very common to reduce losses and to improve the voltage profile in the system. Optimal location and size of DG and capacitors are crucial factors to maximize the loss reduction and to enhance the performance of the network. This paper, proposes an efficient hybrid method based on Genetic Algorithm (GA) and Artificial Bee Colony (ABC) which helps to determine the optimal location and size of DG sources and capacitor banks simultaneously. The main objective is to reduce real power loss in distribution system by placing multiple DG sources and capacitor banks. The proposed method is implemented on IEEE 33 and 69 bus radial distribution systems and results show the method is more effective than the results presented by other hybrid methods such as GA/PSO and ICA/GA.

Electricity has become a part of day to day life of the people. With the increase in population, electricity demand is also raised. The development of distribution systems (DSs), the optimal utilisation of shunt capacitor banks (SCBs) and distributed generators (DGs) in the DSs are heightened. In this paper, a methodology is proposed to allocate both DGs and SCBs simultaneously on the DS. The objectives are to minimise power loss, improving the voltage profile and voltage stability index (VSI) of the DS. First locations of DGs and SCBs are found out by loss sensitivity factor (LSF) technique. Next grasshopper optimisation algorithm (GOA) is used to determine the rating of these sources. The methodology is implemented on IEEE 33 and 69 bus test systems considering optimal allocation of multiple DGs without and with placement of capacitors. Finally, the results obtained by the proposed method are compared with GA/PSO and PSO methods.

To obtain the SaDE method, two enhancements have been employed on control parameters of crossover and mutation operators in original DE algorithm. To expands this discussion and shows the robustness of proposed algorithm, three load conditions have been considered, i.e., constant, varying and effective loads. Objective function is introduced for the load conditions. The annual cost is fitness of problem, in addition to this cost, CPU time, voltage profile, active power loss and total installed capacitor banks and their related costs have been used for comparisons.

Interruption of the direct current of a vacuum-arc discharge (VAD) is analyzed with three methods: the connection of a shunt circuit with a capacitor to the discharge chamber, the overlaying of a pulse nonhomogeneous axisymmetric magnetic field upon the discharge, and the combined action of the magnetic field and the shunt circuit. The probability of interruption of the current I = 500 A as a function of the magnetic field induction is obtained for various shunt capacitances within the range 25 ≤ C ≤ 2500 microfarad (μF). It is shown that the probability of interruption for a given magnetic field induction increases as the capacitance is raised and for the given capacitance it increases as the induction is increased. The magnitude of the magnetic system current I m to ensure the current interruption with the probability P = 1 is obtained as a function of the shunt capacitance. The impact of the shunt circuit parameters upon the arc current is analyzed. The time-domain plot of the arc current for the shunt capacitor C = 2500 μF was estimated. Its results agree with the experiment. It is shown that the combined use of the magnetic field and the capacitive shunt circuit is an effective method of VAD direct current interruption.

This article addresses an efficient heuristic-based approach to assign static shunt capacitors along radial distribution networks using the artificial bee colony algorithm. The objective function is adapted to enhance the overall system static voltage stability index and to achieve maximum net yearly savings. Load variations have been considered to optimally scope the fixed and switched capacitors required. The numerical results are compared with those obtained using recent heuristic methods and show that the proposed approach is capable of generating high-grade solutions and validated viability.

This article introduces an efficient heuristic-based approach to assign static shunt capacitors along radial distribution networks using the artificial bee colony algorithm. The objective function is adapted to enhance the overall system static voltage stability index and to achieve maximum net yearly savings. Load variations have been considered to optimally scope the fixed and switched capacitors required. The numerical results are compared with those obtained using recent heuristic methods and show that the proposed approach is capable of generating high-grade solutions and validated viability.

The capacitor placement based on rational reactive power partition can reduce the power loss and increase benefits in middle distribution systems. So this paper proposes a new capacitor placement method based on reactive power partition. First the distribution is partitioned by Depth First Search algorithm and the principle that the reactive power of each partition load is the most similar. Then the number of node is also more similar in each partition. This is helpful for the selection of locations. Secondly the locations and capacity are simultaneously optimized after partition and obtain more benefits. Finally the 94 node distribution system proves the advantage and practicality of the proposed algorithm.

In industrial activities, the load increase with a more production requirements and overloading, however, in some case the power transformer requires to change for a failure or a contingency stage. In this case, a real engineering failure analysis is done for the shunt capacitors explosion in an industrial facility. A new methodology is proposed for the Engineering failure Analysis for capacitors explosions with overloading power transformers condition, the individual and system assessment with an international standard review is developed for a better understanding in the solution proposal. With this new methodology the following Standards should be updated: IEC 60931, IEC 60871, IEC 60110, IEC 60143, IEC 60252, IEC 60358, IEC 61017, IEC 61048 and IEC 61049. The degradation analysis for the power transformer are considered too with the following international standards analysis: Laboratec, Duval, ABNT IEC 60599, IEEE Rogers, IEC 60599 and CIGRE CS 15. A new recommendation for an international standard is proposed, for the critical scenario, contingency stage and finally the solution with the methodology in a real case study in a Gold mining located in Colombia.

In recent years, two series reactor faults occurred when a 35kV shunt capacitor bank was cut by a circuit breaker in a 500kV substation in Shenzhen. The reason is analyzed that the large inrush current and overvoltage generated during the switching process caused interturn short circuit fault of the reactor, which seriously threatens the safe operation of the system. To avoid such faults, intelligent phase-controlled short-circuit breakers were used to suppress the closing inrush current and reduce the probability of reignition. To verify the effectiveness of the technology, this paper introduces the causes of switching inrush current and over-voltage and the principle of phase-controlled suppression technology, and then applies the technology to a 500kV substation in Shenzhen. Multiple switching tests are carried out on the intelligent and ordinary circuit breakers respectively. The results show that the maximum inrush current generated by the ordinary circuit breaker is 4.2p.u., and the overvoltage is 1.81p.u. While the maximum inrush current of the intelligent phase-controlled circuit breaker is 2.3p.u., and the overvoltage is 1.4p.u. The results confirm that the application of the intelligent phase-controlled switching technology can suppress the inrush current and overvoltage, thus fundamentally improving the reactive switching efficiency and system safety.

Shunt capacitor is the main method to intensively compensate reactive power in the power system. The external discharge circuit, commonly discharge coil which is an inductance coil with low resistance, must be allocated to the large capacity of capacitor. This paper calculates and compares two kinds of circuit, capacitor placed with a discharge coil or a resistance, to find the best way to discharge the residual charge of capacitor. Through the study, in the under damped case, these two kinds of circuit present different discharge properties. In over damped mode, their discharge properties are similar.

In this article, a Cuckoo search optimization-based approach has been applied to allocate static shunt capacitors along radial distribution networks. The objective function is adapted to reduce the system peak losses, to support the system voltage profile, and to improve overall system power factor. Higher potential buses for capacitor placement are initially identified using a power loss index. At that moment, the proposed approach identifies optimal sizing and placement and takes the final decision for optimum location within the number of buses nominated with a minimum number of effective locations and with fewer injected VARs. The overall accuracy and performance of the proposed approach have been validated and tested on 33- and 69-bus radial distribution systems. The numerical results are compared with those obtained using recent heuristic methods, and statistical analysis proved that the problem-solving success of the cuckoo search are quite better than other heuristic methods.

This paper proposes the allocation method for capacitor-reactor banks in a distribution system with dispersed generators to reduce the installation costs, the maintenance costs and minimize the loss of electrical energy. The expected lifetime and maintenance period of devices with moving parts depends on the total number of operations, which affects the replacement and maintenance period for aging equipment under a limited budget. In this paper, the expected device lifetimes and the maintenance period are included in the formulation, and the optimal operation status of the devices is determined using a genetic algorithm. The optimal numbers and locations for capacitor-reactor banks are determined based on the optimal operation status. Simulation results in a 69-bus distribution system with the dispersed generator show that the proposed technique performs better than conventional methods.

Ac line reactor, Dc link reactors and shunt capacitors are mostly used for improving the power factor and reducing the THD level in the adjustable speed drive (ASD) and protecting the device from other power quality problem. The effectiveness of these reactors are affected by many other factors such as loading and source impedance. Under variable load conditions such factors are analyzed and performance of system also analyzed. In this paper simulation is done by inserting such factor which also suggested for future real time applications.

In order to solve the problem in reactive power compensation of oilfield distribution systems at present, a Taboo search algorithm is proposed in this paper, by which the optimal location and size of shunt capacitors on distribution systems are determined. Then the voltage profile is improved and the active power loss is reduced. In this paper, Voltage qualified is used as objective function to search an initial solution that meets the voltage constraints so that it is feasible in practicable voltage range; then the global optimum solution can be got when taking the reduced maximum of active power loss as objective unction. The examples show that the improved algorithm is feasible and effective.

The increase of harmonic current circulation in electric system affects the shunt capacitor banks protection arrangement, causing false alarms and trips and leading to a reduction of the relay sensitivity. This paper analyzes the behavior of the protection system on a reduced-scale model, which reproduces the main features of grounded wye shunt capacitor banks. In such experiments, high levels of current harmonic distortion, voltage unbalance, and bank inherent unbalance were considered. This paper brings experimental analyses for protection arrangements considering robustness and sensitivity.

Combined with the actual situation of transformer substation, PSO model is built to optimize the shunt capacitor series reactance rate in this paper. First, system harmonic impedance is analyzed and the harmonic impedance model is built. Second, the objective function and constraints of the optimization algorithm were set. The goal is to make the current distortion rate of high side smallest under the condition of the capacitor banks working safely, the output results will be the optimal allocation of the series reactance rate. Current-limiting reactor was also considered the influence to the design of series reactance rate. At last, testify the effectiveness with comparing the effect to the traditional way of designing the series reactance rate and prove the significant influence of the current-limiting reactor.

To control the reactive power, voltage regulation is very difficult in power system from aspects of load compensation. Reduce the power losses and voltage improvement as main aim to compute best setting of shunt devices such as shunt capacitors, SVC, tap changing transformers etc., in power system, when load will gradually increased, then automatically voltage is not maintain reference value due inductive load and energy storage elements. In this paper proposed reduce the power losses and improve voltage profile by using SVC and , switched capacitors with co-ordination have been included in the system. The proposed system has been validated to 9-bus test system considered.

Investigations are done in this paper to see how Tier-2 compensation technique can expand the power systems corridor for the release of embedded transmission capacity. Mathematical models where developed for the savings in power bills, savings in energy and release of systems capacity for extra loadings. The General Steel Mills (GSM) Ltd, Asaba Nigeria was used as a case study to view the effect of locally generated VAr (shunt capacitors) at the buses. These generated VAr corrected the power factors of the load to as close to unity as possible and consequently released the overall systems capacity by 75% with energy and power bills saved to 66% and 23.17Mvar respectively. When this was achieved, the loads being supplied by the transformers was reduced hence the required reactive power by the loads were being supplied at the load locations. These relieve the transformers and the lines of some duties.

Because of the large capacity and compact structure of the UHV compact shunt capacitor, it is difficult to take effective measures to detect and prevent the faults. If the fault capacitor fails to take timely maintenance, it will pose a threat to the safe operation of the system and the life safety of the maintenance personnel. The development of UHV compact shunt capacitor on-line monitoring system can detect and record the on-line operation information of UHV compact shunt capacitors, analyze and evaluate the early fault warning signs, find out the fault capacitor or the capacitor with fault symptom, to ensure safe and reliable operation of the system.

Phase velocity compensation technologies using asymmetric coplanar waveguides (ACPW) with or without defected ground structures (DGS) are proposed to enhance the directivity of wideband 3-dB broadside-coupled coplanar waveguide (BC CPW) couplers. First, even- and odd-mode analyses of BC CPW couplers with four shunt capacitors are performed to obtain closed-form design formulas. Then, ACPW instead of the shunt capacitors are inserted to the input and output ports of the coupler to improve the directivity. Lastly, DGS combining with ACPW are applied to further improve the directivity and broaden the bandwidth. The measured results show that only using ACPW, the bandwidth for the directivity of better than 20 dB is 44.2% with a maximum directivity of 42.6 dB. When both ACPW and DGS are used, the bandwidth for the directivity of better than 20 dB is 63.3%, and that for the directivity of better than 30 dB is enhanced to 21.3% with a maximum directivity of 55.9 dB, which is more than 10 dB over the existing BC CPW couplers. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:59–67, 2014.

A new approach toward embedding barium-strontium-titanate (BST) patches into a commercial low temperature cofired ceramic (LTCC) is described, using a tape transfer technique. Pressure-assisted sintering is successfully employed to achieve flat multilayer multimaterial modules without internal cracks or delaminations. Apart from the description of the processing technology, the paper also presents a specific procedure of determining the microwave properties of embedded thick BST films, which is based on using the experimental evaluation of a shunt capacitor. The permittivity of the embedded BST determined at room temperature is about 214 and remains constant at least from 100 MHz up to 8 GHz. In addition, the effects of temperature and bias voltages on the microwave properties of LTCC BST were studied systematically from 1 MHz up to 8 GHz. We observed a tuning of the permittivity by about −49%, either by raising the temperature from 21°C to 125°C, or by applying a bias electrical field of up to 10 V/μm. Additionally, breakdown voltages were investigated. The embedded BST withstands field strengths of more than 20 V/μm under laboratory conditions.

Objectives: A shunt capacitor bank with appropriate switching control using relay and circuit breakers is proposed to compensate reactive power in an 11kV Malaysian test distribution system with high density commercial load. Methods: Fuseless Capacitor Bank will be modelled according to IEEE standard using MATLAB. The designed switching control for the fuseless capacitor bank will perform condition checking based on the criteria of power factor and determine the best control action to be taken in order to compensate reactive power in the power system effectively. The designed system is then tested on an 11kV Malaysian test distribution system with high density commercial load. Findings: Simulation results clearly indicate that the designed system is able to react and compensate reactive power adequately in accordance to Malaysia’s utility regulations. Improvements: For future improvements, criteria focused on both voltage and power factor can be implemented to minimize power loss in the system.

The integration of shunts capacitor in the distribution system can have significant effects on the behavior of the system. An improper insertion of this equipment can cause negative impacts, the solution of these impacts requires an optimal location of shunt capacitors with adequate power injected. The main objective of this study is to determine the optimal placement and size so that the maximum annual benefit due to peak power and reduce energy loss, compared to the cost of installation be minimal. So it is necessary to use optimization techniques that we used the Particle Swarm Optimization (PSO) algorithm to solve this problem. The technique has been validated and tested on different types of distribution network including three IEEE standard networks (10 bus, 15 bus and 34 bus) and applied on a real network of Algerian distribution system.

Background/Objective: This paper presents regulation of Self Excited Induction Generator (SEIG) as asynchronous generator in standalone mode for wind energy conversion system (WECS). Methods/Statistical Analysis: The proposed controller consists of Voltage Source Converter (VSC) having bidirectional active & reactive power flow control, integrated with Battery Storage Unit (BSU), connected in shunt. It compensates for variable reactive power with variable active power. Rating of induction machine has been obtained by short circuit test, open circuit test and synchronous speed test. Findings: SEIG have relative advantage over conventional synchronous generator. However, vo1ltage and frequency regulation are among prime challenges in its practical application as standalone generator. Voltage and frequency of SEIG depends upon speed of rotor, shunt capacitor and load. A suitable control scheme needs to be developed to ensure minimum variation in voltage and frequency for variable input and electrical load. Voltage regulation has been achieved by adjusting reactive power provided by static compensator consisting of inductor a VSC and dc bus capacitor. Conclusion/Improvement: The simulation results show that voltage and frequency of SEIG-WECS have negligible variation for resistive, reactive, balanced, unbalanced and nonlinear load under varying wind speed and consumer load. It eliminates harmonic contents and balances the connected electrical load.

The configuration and setting of shunt capacitor bank protection is very important to ensure the safety of power system and power equipment. This paper introduces the shunt capacitor banks connection and shunt capacitor banks protection configuration of the UHV pilot project from Southeast Shanxi via Nanyang in Henan province to Jinmen in Hubei province. The application principle on the configuration and setting of this 110 kV shunt capacitor banks protection is studied and discussed in detail. The principle to ensure the safety of power equipment is chiefly taken into account in order to achieve a reasonable configuration and setting.

The paper describes numerical base of user defined component model (UDC) for real time digital simulator (RTDS), gives applied method of UDC technique combined with user defined steps of assembling shunt capacitor (ASC), compares transient simulating results of ASC UDC with models from RTDS library, and demonstrates UDC possess higher simulating efficiency and simulating quality is not decreased.

Allocation of shunt capacitor banks on radial electric power distribution networks allow reduction of energy losses and aggregated benefits. Four decades ago Duran proposed the use of dynamic programming to find optimal capacitor placement on these networks; however, with the restricting assumption of single-ended networks, which precluded its application to real capacitor allocation problems. Subsequently heuristic methods prevailed in the capacitor allocation literature. Here the Extended Dynamic Programming Approach (EDP) lifts Duran’s restricting assumption; a richer definition of state and the projection of multidimensional informations into equivalent one-dimensional representations are the supporting concepts. In addition to allow consideration of multi-ended networks, EDP deals with other requirements of capacitor allocation studies, including the use of both fixed and switched capacitors and representation of voltage drops along the networks. When switched capacitors are considered the optimization procedure also solves the capacitor control problem, obtaining the best tap adjustments for them. Case studies with real scale distribution networks put into perspective the benefits of the methodology; EDP has the appeal of providing global optimal solutions with pseudo-polynomial computational complexity in the worst-case, and with linear complexity for practical applications.

This paper describes CSC(Current Sourced Converters)-based HVDC operational strategy for voltage stability enhancement in the power system. In case of CSC-based HVDC system, rectifier and inverter consume reactive power up to about 60% of converter rating. Therefore, CSC-based HVDC is basically not useful system for voltage stability even if AC filters and shunt capacitors are attached. But, If the particular power system condition is fulfilled, CSC-based HVDC also can be the rapid reactive power source for voltage stability enhancement using a cooperative control with converter and AC filters/Shunt Capacitors. In this paper, the cooperative control algorithm is presented and simulated to 60MW HVDC system in Jeju island.

In this article, a new approach for the genetic algorithm is applied to solve the optimal power flow problem based on different objective functions. The main distinction of this technique is in using the adapted genetic algorithm with adjusting population size. The objective functions are minimized using various controlled system variables (generator voltages, transformer taps, and shunt capacitors). The feasibility of the proposed method is presented on the IEEE 30-bus system and compared to other well-established techniques. A comparison with other methods shows the effectiveness of the proposed technique.

A new type of Class E rectifier that can regulate the output voltage or power is proposed. The proposed rectifier is composed of a conventional Class E zero-voltage-switching rectifier and the controlled shunt capacitor whose capacitance is variable according to the state of the active switches. With turning the active switches ON or OFF, the shunt capacitance of the rectifier can be changed, which enables the rectifier to vary the output voltage or power. This paper presents an analysis, experimental results, and simulation results in the steady state.

This paper explores the capability of modified differential evolution (MDE) technique for solving the reactive power dispatch (RPD) problem. The proposed method is based on the basic differential evolution (DE) technique with a few modifications made into it. DE is one of the strongest optimization techniques though it suffers from the problem of slow convergence while global minima appear. The proposed modifications are tried to resolve the problem. The RPD problem mainly defines loss minimization with stable voltage profile. To solve the RPD problem, the generator bus voltage, transformer tap setting and shunt capacitor placements are controlled by the MDE approach. In this paper, IEEE 14-bus and IEEE 30-bus systems are chosen for MDE implementation. The applied modification show much improved result in comparison to normal DE technique. Comparative study with other softcomputing technique including DE validates the effectiveness of the proposed method.

The Load Tap Changing (LTC) transformer and Shunt Capacitor (SC) bank are major devices for voltage and reactive power control in a distribution substation. Thus, the coordination operation of a LTC transformer and a SC bank is required to achieve better voltage and reactive power compensation at a distribution substation in the same time. This paper proposes coordinate control method of LTC transformer and SC bank to achieve better voltage and reactive power compensation and operation times of these two devices in the same time. The mathematical formulations of the proposed coordinate control method are introduced. Sample case studies are shown to verify the effectiveness of the proposed coordinate control method.

The new reality of smart distribution systems with use of generation sources of small and medium sizes brings new challenges for the operation of these systems. The complexity and the large number of nodes requires use of methods which can reduce the processing time of algorithms such as power flow, allowing its use in real time. This paper presents a known methodology for calculating the power flow in three phases using backward/forward sweep method, and also considering others network elements such as voltage regulators, shunt capacitors and sources of dispersed generation PV and PQ. After that, new elements are introduced that allow the parallelization of this algorithm and an adequate distribution of work between the available processors. The algorithm was implemented using a multi-tiered architecture which allows its use even in environments with low processing power, such as smartphones and tablets, and the processing times were measured in many network configurations and compared with the same algorithm in the serial version.

This letter describes a miniaturized bandstop frequency-selective structure (FSS) based on the stepped-impedance resonator (SIR). The FSS consists of a two-dimensional periodic array of vertical microstrip SIRs for thickness reduction. A shunt capacitor connecting the SIR center and ground is employed to widen the operating bandwidth and to improve the quasi-elliptic filtering response. It is shown that more than 40% thickness reduction of the FSS can be realized by choosing a small impedance ratio of the SIR, and a steep quasi-elliptic bandstop filtering performance is achieved by adjusting the value of the shunt capacitor. As an example, a prototype of the proposed FSS is designed, fabricated, and tested. The good agreement between simulated and measured results verifies the design concept of the miniaturized FSS.