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The never-ending issue of inadequate energy availability is constantly on the outermost layer. Consequently, an ongoing effort has been made to improve electric power plants and power system configurations. Photovoltaic Distributed Generators (PVDG) and compensators such as Distributed Static Var Compensator (DSVC) are the center of these recent advances. Due to its high complexity, these devices’ optimum locating and dimensions are a relatively new issue in the Electrical Distribution Grid (EDG). A modified version of Newton Raphson Based Optimizer (mNRBO) has been carried out to optimally allocate the PVDG and DSVC devices in tested IEEE 33 and 69 bus EDG. The mNRBO algorithm integrates four parameters to enhance NRBO’s performance by addressing its limitations in balancing exploration and exploitation. The article suggested novel Multi-Objective Functions (MOF), which have been considered to optimize concurrently the overall amount of active power loss (APL), voltage deviation (VD), relays operation time (TR ELAY ), as well as improve the coordination time interval (CTI) between primaries and backup relays set up in EDG. The proposed mNRBO algorithm surpasses its basic NRBO version, as long as another alternative algorithm, while providing very good results, such as minimizing the APL from 210.98 kW until 26.482 kW and 224.948 kW until 18.763 kW for the IEEE 33 and 69 bus respectively. Which proves the capability of the mNRBO algorithm of solving such power system challenges.

This paper presents an improved directional overcurrent protection scheme using a two-stage hybrid GA-IPM algorithm. The developed approach considers the optimal time-current characteristic (TCC) selection and setting calculations of DOCRs simultaneously to protect meshed power networks. The developed formulation considers the optimal choice of the TCC curve and setting calculation simultaneously. Here, the problem is formulated as a mixed-integer nonlinear programming (MINLP) problem where a curve selection setting called curve-setting (CS) is added to the standard time multiplier-setting (TMS) and plug-setting (PS) of each relay in the DOCRs-based protection scheme. In modern relays, the selection of TCC curves is easily made from the available options. In this work, the IEC-standard curves have been considered to obtain the optimum characteristic curve selection and setting calculations. The formulated MINLP problem has been solved using the newly developed two-stage hybrid GA-IPM algorithm. In the first stage, the genetic algorithm (GA) is used to solve the problem formulated as MINLP. The obtained solution is considered the initial solution for the interior-point method (IPM) in the second state. The GA can solve the MINLP problems effectively, and IPM is superior in solving nonlinear programming problems, hence fine-tuning the results obtained by GA. The suitability and effectiveness of the proposed approach have been demonstrated on the IEEE 14 bus test system. Further, the efficacy of the developed method has been validated on an extensive IEEE 118 bus test system, and results are compared with those available in the literature.

At present, the integration of renewable energy source (RES) is increased in the distribution network to meet the escalating power demand. When the distributed system is used with renewable resources, it needs more protection techniques. The design of protection in the distribution network is difficult because of renewable resource integration. In order to overcome these issues, an adaptive protection method with directional overcurrent relay (DOCR) coordination using hybrid chaotic artificial humming bird optimization is proposed. In this work, the IEEE 30 bus distribution system is modified by adding RES like PV, wind, diesel and battery to meet the energy demand. In addition, the relay characteristics and settling are examined using hybrid chaotic artificial humming bird optimization (HCAO). The proposed optimization algorithm optimizes the value of the time dial setting (TDS) and the plug setting multiplier (PSM) to reduce the service time of the relay. The proposed work is implemented with IEEE 30 bus system in MATLAB. The proposed HCAO is validated on IEEE 26 and IEEE 14 bus systems. Existing optimization algorithms, such as African vulture and battle Royale optimization, are compared with the HCOA on the IEEE 30 bus system to show the performance efficacy.

As an effective approach to achieve the “dual-carbon” goal, the grid-connected capacity of renewable energy increases constantly. Photovoltaics are the most widely used renewable energy sources and have been applied on various occasions. However, the inherent randomness, intermittency, and weak support of grid-connected equipment not only cause changes in the original flow characteristics of the grid but also result in complex fault characteristics. Traditional overcurrent and differential protection methods cannot respond accurately due to the effects of unknown renewable energy sources. Therefore, a longitudinal protection method based on virtual measurement of current restraint is proposed in this paper. The positive sequence current data and the network parameters are used to calculate the virtual measurement current which compensates for the output current of photovoltaic (PV). The waveform difference between the virtual measured current and the terminal current for internal and external faults is used to construct the protection method. An improved edit distance algorithm is proposed to measure the similarity between virtual measurement current and terminal measurement current. Finally, the feasibility of the protection method is verified through PSCAD simulation.

This paper proposes a new approach to the distributed generation system protection coordination based on directional overcurrent protections with inverse-time characteristics. The key question of protection coordination is the determination of correct values of all inverse-time characteristics coefficients. The coefficients must be correctly chosen considering the sufficiently short tripping times and the sufficiently long selectivity times. In the paper a new approach to protection coordination is designed, in which not only some, but all the required types of short-circuit contributions are taken into account. In radial systems, if the pickup currents are correctly chosen, protection coordination for maximum contributions is enough to ensure selectivity times for all the required short-circuit types. In distributed generation systems, due to different contributions flowing through the primary and selective protections, coordination for maximum contributions is not enough, but all the short-circuit types must be taken into account, and the protection coordination becomes a complex problem. A possible solution to the problem, based on an appropriately designed optimization, has been proposed in the paper. By repeating a simple optimization considering only one short-circuit type, the protection coordination considering all the required short-circuit types has been achieved. To show the importance of considering all the types of short-circuit contributions, setting optimizations with one (the highest) and all the types of short-circuit contributions have been performed. Finally, selectivity time values are explored throughout the entire protected section, and both the settings are compared.

This paper presents a new table based algorithm for overcurrent relay with inverse-time characteristic. The algorithm is based on loading the adequate time vector through which inverse-time characteristic is modeled. It uses samples of the current and calculates rms value. The rms current represents an input value for the index estimation what determines corresponding element from already loaded time vector. Since the calculations used in this algorithm are based on simple mathematical operations, short processing time is achieved. Performances of the algorithm are tested by several computer-generated signals. Furthermore, comparative analyses showed indisputably that suggested procedure possesses significant advantages compared to other solutions: simplicity, high speed of operation and accuracy.

Inverse time overcurrent relays are widely used for the protection of distribution networks. They detect the current caused by a short circuit fault and after an appropriate time delay disconnect the faulted item of plant from the network. Many electrical faults, especially those occurring on underground cables, are intermittent in nature and are commonly referred to as “pecking” faults. Such faults are highly unstable, and the fault arc repeatedly flashes over and then recovers. This “on-off” behaviour of the fault current adversely affects the operating times of overcurrent relays; and this can create grading problems, especially if a feeder is protected with a mixture of electro-mechanical, static and numerical relays. For example if the amplitude of the fault current changes from “high-low-high...etc” an upstream relay may eventually initiate the spurious tripping of a circuit breaker and black-out a large section of the network, that includes healthy feeders and the downstream faulted component. The actual response of a relay to a pecking fault depends on the reset behaviour of the actual or virtual operating disc. For example, if the duration of one fault current pulse is insufficient to operate the relay and if the reset time of the relay is shorter than the time between successive pulses of fault current, then the relay will never operate; however, if the reset time is longer than the off current period, the disc will effectively integrate the effect of the fault current pulses and after multiple pulses trip the relay. This paper investigates the impact of repetitive pecking faults on the operating times of different generations of overcurrent relays and recommends a solution to the coordination problem seen on a network during an intermittent fault.

This chapter contains sections titled: Chapter Overview Protection against Overcurrent and Short Circuit Overvoltage Protection Protection against Overtemperatures Protection against Internal Faults Protection by Balance Observation at Single‐Phase MV Capacitors Summary Reference