Shunt Capacitor Banks Research Articles

Power Quality Improvement of Distribution Network Using BESS and Capacitor Bank

The power demand around the world is increasing rapidly. The aging distribution network architectures are used by the existing utility companies to deliver power to the consumers, which significantly affects the reliability, stability and quality of the delivered power. Different techniques such as compensation devices have been used by power system engineers and researchers to maintain the quality of power transmitted to end users. In this paper, wattage and volt-amp reactive (VAR) planning scheme has been proposed by using the combination of battery energy storage systems (BESS) and compensators to deal with the vulnerability of networks to voltage drop and system inefficiency. The cost-effective combination of BESS and shunt capacitor bank will then be analyzed to indicate the benefit of the proposed scheme.

Siting and Sizing of Distributed Generation and Shunt Capacitor Banks in Radial Distribution System Using Constriction Factor Particle Swarm Optimization

This article proffers an advanced solution to allocate the distributed generation (DG) and shunt capacitor (SC) banks optimally in radial distribution system (RDS) to alleviate the power losses, revamp the voltage profile, inflate the voltage stability index, shrink the total voltage deviation, and acquire more energy savings. In the framework of finding the optimal site and size of DGs and SC banks, Particle swarm optimization (PSO) technique is modified with constriction factor and the same is aimed to apply in IEEE 33-bus system and practical Brazil 136-bus RDS. Different case studies are carried out for multiobjective problems while considering equality and inequality constraints. A comparative analysis with PSO and modified PSO is presented to project the precedence of the adopted algorithm. In addition, the obtained results are also compared to the recently surfaced few state-of-the-art algorithms to present the optimizing capability of the implemented algorithm.

Comprehensive impact analysis of ambient temperature on multi-objective capacitor placements in a radial distribution system

Shunt capacitor banks (SCBs) are used in distribution systems for loss reduction, voltage stability improvement for the system nodes, and system capacity release. However, the size of these capacitors and their placement locations are design factors that have been considered as single or multi-objectives to derive maximum benefits from their installation. To find the optimal location and size of the SCBs, this study proposes the application of multi-objective salp swarm algorithms, considered at ambient temperature, in radial distribution systems. Additionally, a fuzzy-based mechanism has been utilized to identify the best-fit solution of three different objective functions. The proposed method is implemented on IEEE 15-bus and 33-bus radial distribution systems, as well as on real data taken from the Saudi Electricity Company. The results indicate improved effectiveness and higher capability of the proposed method.

Analysis, Design, and Implementation of Junction Temperature Fluctuation Tracking Suppression Strategy for SiC MOSFETs in Wireless High-Power Transfer

In order to improve system reliability and reduce device thermal fatigue failure in multiload wireless power transfer (WPT) systems for electric vehicles, the implementation of the junction temperature fluctuation suppression strategy for SiC MOSFETs is necessary. However, current methods are relatively lacking, and active thermal management has not been used in WPT systems. In this article, the relationship between circuit parameters and junction temperature of SiC MOSFET is analyzed. In particular, a junction temperature fluctuation tracking suppression strategy for SiC MOSFETs is proposed, which consists of a coarse and a fine adjustment stage. As for the former, a shunt capacitor bank switching method is implemented. In order to compensate for the coarse adjustment defects in the small adjustment range and poor effect, in fine adjustment stage, a changing driving voltage method is used. Finally, a 5-kW multiload WPT system is built for verification. Experimental results show that the proposed strategy has obvious effect on the suppression of junction temperature fluctuation and keeps temperature near the target temperature. Benefiting from this, the maximum 13.9 °C junction temperature fluctuation is completely eliminated when the power fluctuations are within 36.1% of the rated power, and the heat load of each SiC MOSFET can be independently adjusted.

Novel Method for Location of Internal Faults in Ungrounded Double Wye Shunt Capacitor Banks

Double wye shunt capacitor banks (SCB) are commonly used for reactive power support in high voltage transmission systems. Neutral current unbalance method is often used for protecting double wye SCBs against internal faults. One of the limitations of existing neutral current based unbalance methods is that they fail to detect simultaneous faults (same fault starting time or faults happening between two consecutive protection passes). This paper proposes a novel method for internal fault location in ungrounded double wye fused/fuseless SCBs. The proposed method uses compensated negative sequence and neutral currents to locate the internal faults. The advantage of the proposed method is that it can locate simultaneous faults happening in any of the two legs of SCB. The proposed method can also calculate the number of faulty elements. The performance of the proposed algorithm has been validated using both hardware experiments and software simulations. A laboratory scale prototype of ungrounded double wye SCB has been developed to test the performance of the proposed method. Software simulations have been done using PSCAD software. Results show that the proposed algorithm can locate both single and simultaneous faults even during system voltage unbalances. The proposed algorithm performs satisfactorily during load switching scenarios.

Security-Constrained ACOPF: Incorporating Worst Contingencies and Discrete Controllers

The work reported in this paper aims at developing an algorithm for system operators to solve a robust security-constrained AC optimal power flow (R-SC-ACOPF) problem, which also optimizes the settings of discrete controllers including load tap changers (LTCs) and shunt capacitor banks (SCBs). An iterative algorithm involving a master problem and a number of sub-problems is proposed. The master problem selects the optimal discrete controllers' settings by taking into account primal SC-ACOPF constraints based on the single-component worst contingencies identified by the sub-problems. Each sub-problem is a bi-level max-min problem used to find the current worst contingency. The overall objective is to minimize the total cost, including generation and load shedding cost, while satisfying all relevant constraints. The master problem and sub-problems allow representing LTC tap positions, SCB status, and contingencies using binary variables. Two case studies are presented as applications of this novel technique.

Shunt capacitor bank: Transient issues and analytical solutions

Medium voltage shunt capacitor banks (SCBs) are widely used for improving voltage profile and providing reactive power in electrical networks. Transient oscillations caused by SCBs, e.g., switching and self-excitation phenomena, may damage sensitive equipment in electrical networks. This paper provides an analytical description of the SCB transients and proposes efficient techniques to limit such transients, which include (i) determining the proper size of the SCB to minimum the risk of the self-excitation, (ii) detecting and preventing the SCB self-excitation using a novel protection scheme, and (iii) limiting the SCB switching transients by developing some approaches for medium voltage application. The proposed strategies for limiting SCB transients are verified using comprehensive simulation studies conducted on an actual power system.

Application of Improved Teaching and Learning Based Algorithm for Simultaneous Optimal DG and Capacitor Placement

Proper electrical power distribution system design plays a vital role in delivering the good quality of electrical power to each and every consumer in the system especially end user/consumer. Good quality of electrical power is always be measured with good voltage profiles. In general, due the electrical constants of distribution system feeders, there is a considerable voltage drop due to which voltage at various buses in the distribution system will suffers from poor voltage magnitudes. This can be overcome up to some extent by various methods such as providing the compensating devices like Distributed Generators (DGs) that provides both active and reactive power injections and shunt capacitor banks, that will give reactive support to the system. In this work, an attempt has been made to obtain the optimal locations and optimal sizes of these DGs and shunt capacitors by an algorithm based on improved version of Teaching and Learning based optimization. Basically sensitivity analysis is adopted to find the optimal locations and their optimal sizes are obtained by Improved Teaching and Learning based Optimization algorithm. The proposed work has been tested with a radial distribution test systems i.e., IEEE-41bus system and results are presented.

A Novel Method of Optimal Capacitor Placement in the Presence of Harmonics for Power Distribution Network Using NSGA-II Multi-Objective Genetic Optimization Algorithm

One of the effective ways of reducing power system losses is local compensation of part of the reactive power consumption by deploying shunt capacitor banks. Since the capacitor’s impedance is frequency-dependent and it is possible to generate resonances at harmonic frequencies, it is important to provide an efficient method for the placement of capacitor banks in the presence of nonlinear loads which are the main cause of harmonic generation. This paper proposes a solution for a multi-objective optimization problem to address the optimal placement of capacitor banks in the presence of nonlinear loads, and it establishes a reasonable reconciliation between costs, along with improvement of harmonic distortion and a voltage index. In this paper, while using the harmonic power flow method to calculate the electrical quantities of the grid in terms of harmonic effects, the non-dominated sorting genetic (NSGA)-II multi-objective genetic optimization algorithm was used to obtain a set of solutions named the Pareto front for the problem. To evaluate the effectiveness of the proposed method, the problem was tested for an IEEE 18-bus system. The results were compared with the methods used in eight other studies. The simulation results show the considerable efficiency and superiority of the proposed flexible method over other methods.

Transient Inrush and Fault Current Signal Extraction Using Discrete Wavelet Transform for Detection and Classification in Shunt Capacitor Banks

An unbalanced current protection relay (60C, 51NC) cannot operate fast enough to avoid catastrophic failure against high system fault currents within capacitor units because a traditional unbalanced current protection relay is not capable of classifying the transient fault current and switching inrush current. This article proposes a new algorithm for the detection and classification of these transient current signals. Simulations are performed using PSCAD/EMTDC programs. The outputs of the current signals are used as inputs for the discrete wavelet transform (DWT) process. The wavelet-based fault and inrush current detection and classification unit receive the captured transient current signals and use DWT to detect and analyze these signals. Actual inrush current signals from an experimental setup and shunt capacitor banks of 115 kV, 22 kV, and 6.6 kV are used to verify the proposed algorithm. The results show that the proposed algorithm provides good performance and accuracy in identifying faults and inrush currents.

Temperature impact assessment on multi-objective DGs and SCBs placement in distorted radial distribution systems

In smart grid distribution systems, the applications of Shunt Capacitor Banks (SCBs) and Distributed Generations (DGs) are widely known and installed for system loss reduction, voltage stability improvement of system buses, and to free up the system loading. However, the installation of SCBs and DGs in distribution systems with distorted waveforms will increase the harmonic distortion level if they are not placed at appropriate locations. In this paper, a Multiobjective Grey Wolf Optimizer (MOGWO) is proposed to find the optimal size and locations of SCBs and DGs simultaneously with regard to the impact of ambient temperature on distorted distribution systems. Electric utilities will be able to reduce system active losses, enhance the voltage stability for system buses, release the section loading, and reduce the total harmonic distortion level. Fuzzy set theory is utilized to choose the optimum compromise solution from the Pareto front solutions of the MOGWO method. The proposed method is applied to IEEE 69-bus and real data taken from the Saudi Electricity Company (SEC). The results show a higher capability in finding optimum solutions for SCBs and DGs placement in distorted Radial Distribution Systems (RDSs) compared to conventional methods.

Simultaneous Allocation of Multiple Distributed Generators and Shunt Capacitor Banks in Radial Distribution Systems using Grasshopper Optimization Algorithm

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.

Simultaneous allocation of multiple distributed generators and shunt capacitor banks in radial distribution systems using grasshopper optimisation algorithm

Simultaneous allocation of multiple distributed generators and shunt capacitor banks in radial distribution systems using grasshopper optimisation algorithm

Combined Impact of Network Reconfiguration and Volt-VAR Control Devices on Energy Savings in the Presence of Distributed Generation

Reduction of energy consumption and energy losses is a major concern of the distribution network operator in the present scenario. Traditionally, on-load tap changers, a shunt capacitor bank, and a voltage regulator have been employed as volt-var control (VVC) devices for savings in energy consumption and losses. In this paper, an efficient and optimally coordinated operation of traditional VVC devices, a distribution network reconfiguration (DNR), and a photovoltaic smart inverter (PVSI) for energy savings has been proposed. In order to achieve the optimal solution, a modified binary gray wolf optimization (MBGWO) algorithm has been proposed. Besides, the proposed method in association with PVSI droop control has been employed to control the voltage violations during cloudy day condition. Furthermore, the proposed method has been employed for service restoration considering voltage regulation and peak demand reduction under faulty condition. For validation, the performance of the proposed algorithm has been tested on balanced as well as unbalanced distribution systems. The test results demonstrate the significance of the DNR associated with VVC devices and PVSI for energy savings under different load models. Outcome of the proposed algorithm has been compared with other existing metaheuristic algorithms and test results demonstrate the benefit of the proposed method.

Static and electromagnetic transient considerations incorporated into shunt capacitor allocation for distribution network using hybrid PSOGSA algorithm

Nowadays the majority of electrical power systems are stricken by some intricacies originating from their running near operational and physical limits due to the restructuring and liberalization. Deploying any apparatus within such a system is required all aspects of studies. Shunt capacitor is one of those equipment being utilized for a broad range of objectives including power factor correction, reactive power compensation, system stability improvement, and power loss reduction. So, it is required to investigate all dimensions of its allocation in the light of steady-state along with electromagnetic transients. Regarding a better response of a shunt capacitor bank (CB) to a distribution network, the steady-state study associated with its allocation is generally conducted while in many cases, consideration of electromagnetic transient is omitted. Consequently, it is more likely to cause transient overvoltage and extreme charging/discharging current damaging system equipment severely. In this paper, an integrated approach is proposed to make a compromise between two issues, steady-state study to find the optimal allocation of CBs and capacitor switching with minimum electromagnetic transients. In steady-state study, estimating the optimal allocation of CB is carried out through the hybrid PSOGSA algorithm. A certain privilege of this algorithm is to integrate the ability of exploitation in PSO with the ability of exploration in GSA to synthesize both algorithms’ strength. Moreover, the minimum electromagnetic transient of CB switching amongst the potential allocation sets is identified by a new index. The proposed method is verified by EMTP-RV and MATLAB software and the results show its applicability.

Condition Monitoring of Circuit Switchers for Shunt Capacitor Banks Through Power Quality Data

Aging of power system assets challenges utilities to maintain reliable service while minimizing their maintenance costs. Although malfunction of devices in the transmission or distribution networks can have catastrophic consequences, their failure is seldom unforeseen. Typically, the device aging occurs gradually over time until its health condition reaches a point of complete breakdown. The overall objective of this paper is to devise a non-invasive, online condition monitoring technique of circuit switchers for shunt capacitor banks. It aims to detect abnormal operation of these devices based on features derived from raw voltage and current waveforms, such that a predictive maintenance strategy may be employed before a complete failure occurs. The data analyzed in this paper are collected at a transmission capacitor bus, where the banks are equipped with pre-insertion impedance. Through a baseline range of values for selected parameters, the proposed technique is able to detect missing pre-insertion impedance during the capacitor energizing and failure of pre-insertion impedance switch out a few cycles after the energizing operation.

Incorporating a Nodal Reactive Power Pricing Scheme Into the DisCo’s Short-Term Operation

Distribution networks have undergone fundamental changes driven mainly by the rapid penetration of distributed energy resources. The distributed power sources connected to the distribution wires (often through power inverters) can provide not just active power, but also reactive power support to the grid. Reactive power management is a key aspect that may substantially affect the efficiency and the quality of supply of distribution networks and, as a consequence, the operation of a distribution company (DisCo). This work proposes the integration of an enhanced version of a practical and transparent nodal reactive power pricing scheme into a precise and complete short-term operation model of a DisCo. This model explicitly considers distribution-network-related technical constraints such as dispatchable and intermittent distributed generation units, voltage-sensitive loads, time-varying retail prices, stationary batteries, step voltage regulators, shunt capacitor banks, and demand-related constraints. The resulting model is characterized as a large-scale highly nonlinear and nonconvex program with continuous, binary, and discrete variables. To solve such problem, a pseudo-dynamic Tabu Search–based algorithm is proposed and effectively tested.

Reactive power optimization configuration for distribution network integrated with microgrids

In recent years, distributed generation (DG) and microgrid develop rapidly in distribution network. With the increase of its penetration, the distribution network is faced with many operation challenges such as voltage violation and voltage flicker, etc. Thus, it is urgent to perform reasonable reactive power planning and optimize the operation strategy of reactive equipment to handle the arisen problems in the distribution network. This paper puts up with a reactive power configuration method, optimizing the operation of shunt capacitor bank (C) and static var generator (SVG). The genetic algorithm (GA) is applied to solve the model. It is proved by the modified IEEE33 system that the proposed model could effectively improve the voltage eligibility rate, reduce the grid loss and achieve better economy, which provides the reference for the reactive power optimization configuration for the future distribution network. The method could be applied in the situation of the integration of microgrid with large capacity generation with randomness.

EFFECT OF IN T OF INTERMEDI TERMEDIATE CONNEC TE CONNECTIONS ON THE TIONS ON THE GENERATOR`S ST OR`S STATIC STABILITY

This article provides the influence of the active, inductive capacitive load on the static stability of synchronous generators and compiled the angular characteristics of the generator power at various loads. When a resistive load is connected, an intermediate power extraction of Pr (δ) occurs. It can be defined as the difference Rg (δ) – Ph (δ) = Pr (δ), depending on the angle δ. The presence of this selection leads to an increase in the ultimate in static stability generator power. However, this reduces the possibility of transmitting power to the receiving system. Therefore, we can talk about the ambiguous (positive or negative) effect of the intermediate active load on the static stability of the generator of a single-machine power system. The reactors are connected tightly or through switches at the end points of power transmission lines with a length of over 300 km to prevent over voltages during switching to compensate for the excess reactive power generated by power lines. Capacitor batteries (CB) are sometimes installed and connected at intermediate points of power lines in order to maintain normal voltage levels when transmitting high power fluxes. It should be noted that the conclusions regarding the effect of shunt reactors and capacitor banks on static stability apply to complex power systems

Application Research of 35kv Switching Shunt Capacitor Banks with Phase-Controlled Circuit Breakers

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.