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When inverter‐based distributed generation (IBDG) sources with output current limited by an internal current loop control or other control logic are connected to power system networks, they can affect the short‐circuit current (SCC) despite their small capacities. Therefore, we derive a method to calculate steady‐state SCC from IBDG sources connect...
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... Moreover, overlooking the prediction and inclusion of the SCC contribution from power sources during power system protection studies, network planning, maintenance, and operation can lead to adverse effects for the distribution network (DN) and its stakeholders. These consequences encompass reduced financial income, diminished reliability, resiliency, and robustness, as well as increased interruption time, frequency, and maintenance costs [25]. Addressing this challenge requires estimating or calculating the SCC contribution from each dispersed IBR in the DN across various potential DER integration scenarios and assessing its impact on the DN's protection coordination [11,26]. ...
... The IBRs SCC contribution estimation or calculation can be addressed by mathematical equations, computational simulations, or through laboratory experiments that test commercial smart inverters in faulty scenarios. As the IBR limits its output current through internal controllers, the inverter should be modeled as either an internally limited or unlimited current source for SCC analysis [25]. Therefore, it should be regarded as a current source inverter (CSI) [27,28,29]. ...
... The works of I. Kim [25,33,34] propose a series of SCC calculation in steady-state, using current injection matrices, for balanced and unbalanced situations with the presence of IBRs. New equations are derived to estimate the SCC flowing from IBRs. ...
The rapid integration of inverter-based distributed power generators are posing challenges for the protection of the electrical power system, especially due to the uncertainty and change in the level of short-circuit current (SCC) of distribution feeders. This thesis proposes three approaches. The first is a methodology to estimate the value of the SCC level at the installation points of overcurrent protection devices in distribution networks with high penetration of inverter-based resources (IBRs), for three-phase faults (3LG) and single-phase ground faults (LG). The second proposes a methodology for adjusting the characteristic curve of inverse-time overcurrent relays. And the third, two methodologies for sizing fuses to avoid solidarity tripping or to protect the conductor. The methodologies are applied in scenarios with high penetration of IBRs and do not require communication
links, nor measurement of parameters in real time: minimal need to replace equipment already installed. Considering the estimation of SCC, the methodology presents a good assertiveness when compared with a computational simulation in MATLAB/Simulink. Errors are smaller for 3LG faults (< 2.1%). For LG faults, the errors are smaller when the IBRs are installed in the main fault trunk (< 10.3%) than in the lateral ones (< -13.0%). Despite the high errors, it is possible to estimate an extreme value of SCC to be used in the protection adjustment. In a scenario of 100% penetration of IBRs, there was a miscoordination between the protection devices: relay-relay and relay-fuse. Coordination was re-established using the proposed methodology for extreme IBR installation situations. In this coordination of the inverse time-overcurrent protection, the time dial of the overcurrent relays was modified. This modification accommodates a high penetration range of IBRs and, in the case of 100% penetration, it delayed the protection actuation by a few tens of ms. For fuses, it was found that depending on the level of penetration of IBRs on the lateral branch that the fuse protects, there may be an incompatibility of the limits used for its sizing. This incompatibility happens for high penetration levels when the maximum current through the fuse is higher than its nominal value. Methodologies to avoid sympathetic tripping and conductor protection were applied to calculate the appropriate fuse to protect the lateral branch and the maximum level of penetration required. The maximum penetration level decreases as the IBR can inject a greater SCC (e.g., 1.2 pu or 2.0 pu). The applied methodologies re-established the coordination of the distribution feeder, both for the main trunk and for the side branches. These proposals can be applied to other feeders and the penetration range to be met is defined by the network manager.
... The proposed algorithms, because of their perturbed nature of velocities, are called Particle Swarm Optimization with Perturbed Velocities (PSODE) and GTO Algorithm. The case study of 28-and 85-bus system study is applied with whale's algorithm [7][8][9] The main aim is to reduce power loss [13][14][15], the Dg location from [16] voltage stability power loss index is calculated and reliability of the system [17][18][19][20][21], the optimizing DG allocation problems separately [22][23][24][25] and, PSO, PGS, MINLP, and BFOA are taken as a case "The main aim is to reduce obtained result is contrasted". ...
As per the order of the day, power engineers are keeping their full effort to reduce the line loss below as par level in electrical distribution networks. One of the best and possible solutions to reduce this line loss is capacitor placement which further maintains the bus voltage to the required level. The proper allocation of the capacitor in electrical distribution network takes care of stability and reliability too. In this paper, this issue is addressed by incorporating distribution generation and its power electronic control to compensate, reduce the power loss as well as shape the voltage profile. The location of distributed generation (DG) is identified and allocated by calculating line voltage stability index (VSI). The DG and its sizing are done through probabilistic, stochastic metaheuristic algorithm, Particle Swarm Optimization with Perturbed Velocities Algorithm (PSODE) and Gorilla Troops Optimizer (GTO). The efficiency of radial distributed network loss index is substantiated by testing through 28-bus, and 85-bus IEEE distribution systems. The results obtained prove optimal placement of DG along with improving voltage profile which further reduces power losses.
... Furthermore, if the SCC contribution from energy sources is not correctly predicted and considered during studies of power system protection, network planning, maintenance and operation, then the distribution network (DN) and its stakeholders may face a decrease in financial income, reliability, resiliency and robustness, as well as an increase in maintenance costs, time and frequency interruption [22]. In this context, one of the main challenges is to estimate or compute the SCC contribution by each IBRs dispersed in the DN, within a variety of possible DER integration scenarios, and how this affects the DN protection coordination [9]. ...
... Estimation of the SCC contribution can be approached by mathematical equations, computer simulations or through laboratory experiments that test commercial smart inverters under faulty scenarios. As the IBRs limit its output current by internal controllers, the inverter should be modeled as an internally limited or unlimited current source for an SCC analysis [22]. Thus, it should be considered a current source inverter (CSI) [23][24][25]. ...
... A series of SCC calculations in steady-state, using current injection matrices, for balanced and unbalanced situations with the presence of IBRs, was proposed by I. Kim [22,28,29]. New equations were derived to estimate the SCC flowing from IBRs. ...
This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values and changing the TMS of OCPDs accordingly. The method is validated by comparing the results with simulations on the IEEE 34-Node Test Feeder using MATLAB/Simulink, which shows an average error of 1.5% and a maximum error of 3.0%. For a 100% penetration level, the SCC variation through OCPDs installed on the main fault trunk (MFT) exceeds ± 10%, leading to compromised phase protection coordination. The SCC flowing reversely through OCPDs on lateral branches and the fault on the MFT could cause improper tripping. Higher SCC levels are estimated and measured for fault impedances equal to zero. The phase protection is restored by changing the TMS of OCPDs using the estimated values. The study proposes two phase protection schemes to accommodate inverter-based DERs injecting 1.2 pu and 2.0 pu of SCC for a 100% penetration level. This study contributes to improving the protection coordination of distribution networks with high penetration levels of DERs. The findings have practical implications for distribution system operators and planners to maintain safe and reliable operation of distribution feeders.
... Furthermore, if the SCC contribution from the power sources is not correctly predicted and considered during power system protection studies, network planning, maintenance and operation, the distribution network (DN) and its stakeholders may face a decrease on financial income, reliability, resiliency, and robustness, and an increase on interruption time and frequency, and maintenance costs [19]. In this context, one of the main challenges is to estimate or calculate the SCC contribution by each of dispersed IBR in DN within the variety of possible DER integration scenarios, and how it affects on the DN protection coordination [9]. ...
... The SCC contribution estimation or calculation can be addressed by mathematical equations, computational simulations, or through laboratory experiments that test commercial smart inverters in faulty scenarios. As the IBRs limit its output current by internal controllers, the inverter should be modeled as an internally limited or unlimited current source for a SCC analysis [19]. Thus, it should be considered as a current source inverter (CSI) [20,21,22]. ...
... The works from I. Kim [19,25,26] propose a series of SCC calculation in steady-state, using current injection matrices, for balanced and unbalanced situations with the presence of IBRs. New equations are derived to estimate the SCC flowing from IBRs. ...
This paper proposes a practical approach to estimate the symmetrical short-circuit current (SCC) levels in overcurrent protection devices (OCPDs) installed on radial feeders for any penetration level of inverter-based distributed energy resources (DERs). The proposed method restores the lost phase protection coordination by estimating SCC values and changing the TMS of OCPDs accordingly. The method is validated by comparing the results with simulations on the IEEE 34-Node Test Feeder using MATLAB/Simulink, which shows an average error of 1.5% and a maximum error of 3.0%. For a 100% penetration level, the SCC variation through OCPDs installed on the main fault trunk (MFT) exceeds ± 10%, leading to compromised phase protection coordination. The SCC flowing reversely through OCPDs on lateral branches and the fault on the MFT could cause improper tripping. Higher SCC levels are estimated and measured for fault impedances equal to zero. The phase protection is restored by changing the TMS of OCPDs using the estimated values. The study proposes two phase protection schemes to accommodate inverter-based DERs injecting 1.2 pu and 2.0 pu of SCC for a 100% penetration level. This study contributes to improving the protection coordination of distribution networks with high penetration levels of DERs. The findings have practical implications for distribution system operators and planners to maintain safe and reliable operation of distribution feeders.
... Hence the sum of positive and negative sequence components of j th bus voltage V 0 abc j is calculated using Equation(26). The zero sequence component of the jth bus voltage V 0abc j ...
This paper proposes a new load flow and short‐circuit analysis method for unbalanced distribution system incorporating three‐phase transformer models and inverter‐based distributed generation (IBDG). Initially, a load flow method of an unbalanced distribution system is developed in this paper, which incorporates the mathematical model of three‐phase transformer of any vector group and different modes of operation of IBDG. The advantage of the proposed method is that the required simulation time for the proposed method is smaller than the backward/forward method available in the literature. The fault analysis method developed subsequently in this paper also incorporates three‐phase transformer model and IBDG in the short‐circuit calculations. The mode of operation of IBDG during short‐circuit analysis depends upon the magnitude of its short‐circuit capacity. The results obtained from the proposed method have been compared with the time domain simulation studies carried out using PSCAD/EMTDC software to verify the accuracy of the proposed method. In the proposed work, the analysis tools have been developed for the operation of unbalanced distribution systems along with inverter‐based distributed generation and utility transformer models under normal as well as abnormal operating conditions. These tools will be helpful for making decisions to perform reliable operation of the system under normal and abnormal conditions. Also, the short‐circuit analysis tool will provide the information for the re‐coordination of protective equipment placed in distribution network.
... If a stationary DG is connected to the grid, it works as a current source, so we need to conduct current source analyses in addition to a voltage source analysis. For such an analysis, the detailed current injection method is introduced in other studies [30][31][32]. For example, the current source is located on the transformer side of the positive-sequence circuit, so the fault current can be calculated as: ...
The power requirements of grids have risen as artificial intelligence and electric vehicle technologies have been used. Thus, the installation of distributed generators (DGs) has become an essential factor to streamline power grids. The objective of this study is to optimize the capacity and location of DGs. For this purpose, an objective function was defined, which takes into account the fault current and the levelized cost of energy, and a modified particle swarm optimization method was applied. Then, we analyzed a case of a single line-to-ground fault with a test feeder (i.e., the IEEE 30 bus system) with no DGs connected, as well as a case where the DGs are optimally connected. The effect of the optimally allocated DGs on the system was analyzed. We discuss an optimal layout method that takes the economic efficiency of the DG installation into account.
