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The capacitor bank and synchronous condenser have been the only available sources of reactive power. Nowadays, most of the appliances use a power electronic interface for their connection. Applying a power electronic interface addsmany features to these appliances. One of the promising features is their capability to interact with Volt-VAR programs. In this paper was investigated the reactive power interaction of the end-user appliances. For this purpose, the distribution network buses are ranked based on their effectiveness, followed by studying their interaction in the Volt-VAR program. To be able to consider the uncertainties, Probability Density Function (PDF) curve was discretized to represent different scenarios, and the reduction method was utilized to reduce the situations. [ABSTRACT FROM AUTHOR]

The optimal VAr compensation using capacitor banks (CBs) in radial distribution networks (RDNs) is solved in this paper while taking the growth of the load from electric vehicles (EVs) into consideration. This is accomplished by adapting an improved variant of the flower pollination algorithm (IFPA) with an enhanced local search capability. The primary objective of determining the locations and sizes of CBs is to minimize the distribution losses in the operation and control of RDNs. Additionally, the effect of CBs is shown by the increased net savings, greater voltage stability, and improved voltage profile. A voltage stability index (VSI) was used in the optimization process to determine the predefined search space for CB locations, and a double-direction learning strategy (DLS) was then considered to optimize the locations and sizes while maintaining a balance between the exploration and exploitation phases. Three IEEE RDNs were used to simulate various EV load increase scenarios as well as typical loading situations. According to a comparison with the literature, the IPFA produced global optimum results, and the proposed CBs allocation approach demonstrated enhanced performance in RDNs under all scenarios of EV load growth. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a two‐stage planning approach for the efficient utilization of distributed generation (DG) and capacitor banks (CBs) for the simultaneous grid‐connected and islanded operations of the balanced distribution networks. The first stage determines the optimal installation locations and capacities of DGs and CBs using an improved variant of the Jaya optimization algorithm (IJaya) to minimize the power losses and voltage deviation during the grid‐connected operation of the distribution network. The second stage identifies the optimal operating point of the DG and CB combination to carry the maximum load during the islanded network operation under power supply‐demand imbalance conditions. For the second stage, an analytical approach is proposed to identify the best operating power factor for the DG‐CB combination, calculating the power loss, and under‐utilization of the installed real‐reactive power sources. Simulation results on the IEEE 33‐bus grid‐dependent distribution network demonstrate that the proposed IJaya significantly improved the network performance and outperforms various existing optimization methods. In addition, during the network's islanded operation, maintaining the network power factor equal to the source power factor (pfsource) makes the DG‐CB combination operate at their rated capacities. [ABSTRACT FROM AUTHOR]

Hybridization of meta-heuristic algorithms plays a major role in the optimization problem. In this paper, a new hybrid meta-heuristic algorithm called hybrid pathfinder algorithm (HPFA) is proposed to solve the optimal reactive power dispatch (ORPD) problem. The superiority of the Differential Evolution (DE) algorithm is the fast convergence speed, a mutation operator in the DE algorithm incorporates into the pathfinder algorithm (PFA). The main objective of this research is to minimize the real power losses and subject to equality and inequality constraints. The HPFA is used to find optimal control variables such as generator voltage magnitude, transformer tap settings and capacitor banks. The proposed HPFA is implemented through several simulation cases on the IEEE 118-bus system and IEEE 300-bus power system. Results show the superiority of the proposed algorithm with good quality of optimal solutions over existing optimization techniques, and hence confirm its potential to solve the ORPD problem. [ABSTRACT FROM AUTHOR]

The vigorous development of renewable energy has induced multiple sources connected to regional distribution networks. However, the high impedance ground fault that appeared in the distribution network can induce an intermittent arc accompanied by extinction and reignition, which may damage renewable energy generation devices severely. Therefore, the detection of arcing faults is profoundly necessary for practice, but the high impedance arcing fault is easily confused with switches of motor or capacitor bank. In order to solve high impedance arcing fault detection, this paper proposes a high impedance arcing fault detection method that combines complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and Teager energy operator (TEO). Firstly, CEEMDAN algorithm is used to extract the intrinsic mode function (IMF) of transient zero‐sequence current (TZSC). According to the correlation coefficient and waveform similarity, which can select maximum correlation coefficient value as the characteristic component of TZSC; Then, TEO is utilized to track the change of signal in real‐time, meanwhile, wavelet singular entropy (WSE) is applied to calculate the characteristic component of TZSC. In particular, high impedance arcing fault (HIAF), motor switching (MS), and capacitor bank switching (CBS) can be effectively identified by comparing WSE. The effectiveness of CEEMDAN‐TEO detection method is verified by simulation, which owns advantages in extraction accuracy, calculation efficiency, and detection accuracy of feature components. [ABSTRACT FROM AUTHOR]

Summary: Conventionally, voltage profile are regulated by controllers that are not operational flexible to the system dynamism and challenges offered by the integration of renewable energy sources. Consequently, there is a need for the adaptive coordinating mechanism as an interface between the passive network and the new active network. This will provide a platform for the smooth integration of distributed energy resources in most developing countries where traditional network is still operational. This paper proposes an algorithm for real‐time multiperiod adaptive compensation of network reactive power support based on hierarchical structure and decentralized layered multiagent system voltage coordinating scheme. A multiperiod voltage control algorithm replicates the daily load flow evaluation aiming at ameliorating voltage fluctuation over a 24‐hour simulation period. The algorithm applies the decentralized voltage control mechanism to monitor the network parameters and dynamically evaluate the capacity of the capacitor banks (CBs) to be injected for voltage compensation. This mitigates the challenges associated with under and over reactive power compensation experienced in the day‐ahead programming and manual switching operation. The algorithm works in conjunction with an on‐load tap changing transformer (OLTC) and energy storage system (ESS). The ESS complements the OLTC during switching delay, dip in its output root mean square and voltage fluctuation as network loading condition varies. The effectiveness of the proposed method is verified on standard IEEE 33 and 118‐bus distribution systems. The results show an improved voltage performance and reduction in stress/complexity associated with load and renewable generation forecast in manual switching operations. [ABSTRACT FROM AUTHOR]

Microgrid (MG) operation is one of the operational requirements of modern utilities for not only maintaining reliable and uninterrupted supply under faulty conditions but also for achieving desired economic goals in the competitive electricity market environment. Under faulty conditions, the electrical distribution system (EDS) becomes islanded microgrid (IMG) with either micro turbine (MT) or renewable energy (RE) based distribution generation (DG) units. However, the power generation from RE based DGs is stochastic nature and it may become either surplus or deficit to the network connected load. Also, the reactive power (VAr) support from DGs is limited. Under this scenario, there is a need for the integration of energy storage systems (ESSs) and reactive power compensators like switched/ fixed capacitor banks (CBs). In this paper, a novel optimization approach for determining the locations and capacities of ESSs combined with CBs along with DGs is proposed based on improved variant of dragonfly algorithm (DFA). Different performance variables of basic DFA are tuned by a self-adaptive mechanism in SADFA for attaining the global solution with least computational efforts. Simulation results on IEEE 33-bus are compared with literature works and also other algorithms namely basic DFA, PSO, BOA, and FSA. The islanded network is suffered with a loss of 97.1229 kW, whereas, it is reduced to 74.2305 kW, 47.3380 kW and 37.6792 kW, by integrating CBs, DGs and simultaneous CBs and DGs, respectively. Based on the comparative analysis, SAFDA is dominated literature works and all other simulated algorithms. Also, the proposed method for ESSs, CBs and DGs integration is shown its effectiveness for serving the IMG energy requirements with reduced losses and increased economic benefits and its suitability for practical applications. [ABSTRACT FROM AUTHOR]

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This paper presents a system for compensating DC link current pulsation in four-wire inverters with energy storage operating under unbalanced load conditions. This phenomenon occurs when an inverter with an independent power control in each of the phases attempts to locally balance the voltage imbalance in the grid. Such a condition creates a DC link current pulsation, which is destructive for energy storage connected to the DC link. The conditions when this situation appears are presented in detail in the paper. A solution to this problem is proposed in the form of a dual active bridge converter and a capacitor bank to actively compensate this pulsation. The control algorithm is proposed based on a proportional-resonant controller. This paper presents the technical background and method by which the controller parameters were calculated, implemented and tested in a real-time system. The test results are presented and discussed, concluding that the proposed solution is an attractive option for protecting the energy storage from DC link current pulsation. The dual active bridge converter combined with resonant controller can compensate the DC link current pulsation almost entirely. [ABSTRACT FROM AUTHOR]

• A new method based on the discrete energy separation algorithm presents to HIF and LIF detection in distribution system. • Simple implementation and low computational burden are main advantages of the method. • The method detects HIF and LIF from other disturbances with high detection accuracy and low detection time even in noisy condition. • The method has proper performance in detection of recorded real HIFs in distribution system. • CT saturation has no impact on the detection accuracy and time of the method in LIF detection. Due to the low fault current of high impedance fault (HIF), it is not recognized by overcurrent relays. Moreover, due to the similar characteristics of HIF and other disturbances like capacitor bank (CB) and non-linear load (NL) switching, detection of HIF is one of the main challenges in protection of distribution system. Furthermore, detection of low impedance fault (LIF) is important for protection system. In this paper, a new statistical method is proposed based on a discrete time separation algorithm of energy for detection of HIF and LIF from other disturbances to improve detection accuracy and time. The method consists of two main parts, the first one detects switching on/off the linear load, switching off the CB and switching off the NL from abnormal conditions, while the second part identifies the HIF and LIF from switching on the CB and switching on the NL. High detection speed, simple implementation, and low computational burden are advantages of the method. The method is tested on IEEE 13-node and IEEE 34-node distribution test systems, and a real feeder in Iran. Obtained results show that the high efficiency of the proposed method in detection of disturbances even in noisy conditions, with low detection time. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of the optimal selection of capacitor banks in electrical AC distribution systems for minimizing the costs of energy losses during a year of operation through a discrete version of the vortex search algorithm (DVSA). This algorithm works with a hypersphere with a variable radius defined by an exponential function where a Gaussian distribution is used to generate a set of candidate solutions uniformly distributed around the center of this hypersphere. This center corresponds to the best solution obtained at the iteration t, which is initialized at the center of the solution space at the iterative search beginning. The main advantage of combining the exponential function with the Gaussian distribution is the correct balance between the exploration and exploitation of the solution space, which allows reaching the global optimal solution of the optimization problem with a low standard deviation, i.e., guaranteeing repeatability at each simulation. Two classical distribution networks composed of 33 and 69 nodes were used to validate the proposed DVSA algorithm. They demonstrated that the DVSA improves numerical reports found in specialized literature regarding the optimal selection and location of fixed-step capacitor banks with a low computational burden. All the simulations were carried out in MATLAB software. [ABSTRACT FROM AUTHOR]

With many advantages, modular multilevel convert (MMC) has been extensively used in high and medium voltage power transmission projects. The thermal performance and reliability of components in MMC are key issues in system operation. However, in the current research on the reliability of MMC components, there are few methods to improve service lifetime expectancy of the components. This paper proposes a balance control algorithm, based on the cumulative fatigue damage of components, feedback to the control terminal for allocating the sub-module (SM) operating state and generating trigger pulses. Finally, the effectiveness of the proposed algorithm is verified and discussed in case studies. It is found that this algorithm is able to improve the aging degree of components in the meanwhile, the improvement in MMC reliability comes at the cost of slightly increasing capacitor voltage fluctuations and total harmonic distortion (THD). Due to the limitation of capacitor thermal performance, SM capacitor banks become a weak link in MMC reliability. [ABSTRACT FROM AUTHOR]

• Utilizing some uncomplicated calculations to detect and determine the number of faulty elements. • Discriminating the capacitor units' failures that may happen simultaneously or with sub-cycle delays in one phase. • The proposed algorithm will help the capacitor units be easily monitored for the different protection design (i.e., fuseless and internally fused units). • Eliminating the transient DC component in the case of external short circuit fault conditions. Failure in quick detection and location of internal failures in Shunt Capacitor Banks (SCBs) may lead to the negligence of necessary repair processes, consequently laying undesirable effects on the power system operation. This paper puts forward a failure detection and fault location method in SCBs with the double wye connection. The proposed method provides a criterion for relay decision-making based on the neutral voltage and current fundamental phasor component, capable of distinguishing the faulty capacitors and determining the number of capacitor failures in the case of multiple faulty phases. The proposed algorithm can be applied for double wye SCBs considering different protection designs, namely fuseless and internally fused units. The proposed method is designed to monitor and detect consecutive failures based on the existing data from commercial relays. Implementation and performance evaluations are conducted in PSCAD and MATLAB software and also with the help of practical data. Performance evaluations are conducted under different circumstances, namely harmonic distortion and voltage unbalance conditions, multiple internal fault locations, and external faults from the grid. Simulation results show the significance and salient features of the proposed method under different conditions. [ABSTRACT FROM AUTHOR]

Recently, the integration of distributed generators (DGs) in radial distribution systems (RDS) has been widely evolving due to its sustainability and lack of pollution. This study presents an efficient optimization technique named the honey badger algorithm (HBA) for specifying the optimum size and location of capacitors and different types of DGs to minimize the total active power loss of the network. The Combined Power Loss Sensitivity (CPLS) factor is deployed with the HBA to accelerate the estimation process by specifying the candidate buses for optimal placement of DGs and capacitors in RDS. The performance of the optimization algorithm is demonstrated through the application to the IEEE 69-bus standard RDS with different scenarios: DG Type-I, DG Type-III, and capacitor banks (CBs). Furthermore, the effects of simultaneously integrating single and multiple DG Type-I with DG Type-III are illustrated. The results obtained revealed the effectiveness of the HBA for optimizing the size and location of single and multiple DGs and CBs with a considerable decline in the system's real power losses. Additionally, the results have been compared with those obtained by other known algorithms. [ABSTRACT FROM AUTHOR]

This paper proposes a new methodology based on the combination of symbiosis organism search (SOS) and neural network algorithm (NNA), named SOS-NNA, for the optimal planning and operation of distributed generations (DGs) and capacitor banks (CBs) in the radial distribution networks (RDNs) considering single- and multi-objective optimization with various equality and inequality constraints. The multi-objective framework is a weighted combination of five component objectives including active power loss, voltage deviation, voltage stability, load balancing, and supply reliability. In addition, practical voltage-dependent non-linear load models are also examined. Two benchmark instances 33 and 69-bus networks have been utilized to evaluate the effectiveness and feasibility of the proposed SOS-NNA via various case studies. The obtained outcomes for different operating cases and test scenarios reveal that the proper combination of optimal power factor DGs (OPF-DGs) and CBs can boost the network performance indexes to an ever-highest degree for all test networks. A cost–benefit analysis is further implemented to evaluate the economic feasibility of the obtained multi-objective solutions. As a result, the proposed SOS-NNA shows a marked improvement regarding the solution quality compared to the recently well-established optimization algorithms as well as outweighs the original NNA in the performance indexes of the solution quality, convergence speed, and statistical results. In addition, the proposed SOS-NNA has been employed for allocating different DG types in RDNs with the consideration of actual 24-h load profiles and the obtained outcomes contribute to the further improvement of yearly energy loss mitigation as well as cost savings. • A new hybrid algorithm SOS-NNA is proposed for distribution systems optimization. • A multi-objective framework relating to five technical objectives is presented. • The best planning and operation solution is given for distribution systems. • Voltage-dependent load model and hourly generation scheduling cases are examined. • The superiority of proposed hybrid algorithm over other algorithms is verified. [ABSTRACT FROM AUTHOR]

• The EM transients of capacitor switching are integrated into the optimal CB allocation. • The hybrid PSOGSA algorithm is utilized for optimizing the size and location of CB. • A new index is proposed to determine the minimum switching transients. • The best CB allocation has to fulfil both requirements for static and EMT studies. 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This article introduces a problem solution of optimal allocation and hourly scheduling of capacitor banks (C-Bs) using the sine cosine optimization algorithm (SCA) to maximize the cost saving and enhance the system reliability. The impact of reliability enhancement reveals in the objective function as a reduction of energy not supplied cost. The optimal location and size of C-Bs are determined based on two strategies; strategy 1, loss sensitivity factor is used to select the candidate buses after that optimal size of C-Bs is determined by SCA while in strategy 2, the optimal location and size of C-Bs are determined by SCA. The proposed algorithm is tested on IEEE 33 and 69-bus radial distribution systems with different scenarios of single and multi-C-Bs installation. Also the daily load variations have been considered to optimally schedule switched C-Bs steps. The simulation results using Matlab programing environment have been verified using the non-parametric Wilcoxon signed rank statistical test. The superiority of proposed algorithm is also ensured by comparing its results with other optimization methods. [ABSTRACT FROM AUTHOR]

Reactive power compensation with Capacitor Banks (CBs) is one of the most successful approaches used in distribution systems, mainly due to their versatility, long-term acceptance in the power industry, and reduced costs. Most allocation methods, however, lack specific strategies to handle the limited discrete nature of CBs sizes seeking to improve the overall optimization and computational performance. We present an algorithm for the Optimal Placement of Capacitor Banks (OPCB) in distribution systems by means of a hybrid Flower Pollination Algorithm (FPA)–Exhaustive Search (ES) approach. The pollination process itself determines the sets of buses for placement, while CBs sizes and the final fitness values of each pollen are selected after a full-search is conducted in the sizing space. As the sizing phase works on the limited search space of predetermined discrete bank values, the computational effort to find the optimum CB capacity is greatly reduced. Tests were performed on distribution systems of 10, 34, and 85 buses with respect to the objective function, final losses, and voltage profile. The algorithm offers an excellent compromise between solution quality and computational effort, when compared to similar approaches. [ABSTRACT FROM AUTHOR]