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• 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]

• 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]

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]