Abstract. In presence of the DistributedGeneration (DG) brought new chal- lenges to the protection engineers since novel coordination scheme is no longer appropriate with the penetration of the DG. The extreme case is violation to the primary and backup relay selectivity constraint. This violation will have resulted to the degradation of the relay performance. Therefore, this paper proposes the best location of the DG penetration to decrease the effect of the DG presentation to the relay performance using the grey wolf optimization (GWO) algorithm. The impacts of the DG prior to the location of the insertion are implemented to the radial 7 bus test system. As a consequence, the best location of the DG penetra- tion is then identified.
Figure 10 illustrates maximum allowable capacity of a DG for each location of Feeder 1 and its associated loss reduction of Case 3. The figure shows that although the maximum allowable capacity of the DG behind the recloser is rather small, however the percentange of loss reduction is high, to an approximated value of 13%. In contrast, even though the maximum allowable capacity of the DG in front of recloser is high, its impact on the loss reduction is rather low, approximately 3-6%. Similar results can be found for Feeders 3 and 4. Figure 11 graphically presents the results of Case 3. The maximum allowable capacity of a DG at each location along the main line is presented by a circle with its value. The size of the circle is related to capacity of a DG.
The coordination procedure proposed in previous section was tested in a test system adopted from the work reported in , which has been used for testing coordination of DOC relays. This system consists of 6 buses with two synchronous-based distributed generators installed at selected locations to form a microgrid as shown in Fig. 2. In the system, DGs are capable to supply the critical loads during lost of main supply. The test system is assumed to be radial at the first place before systematic coordination is applied. Initially, a radial system relies on OC relays as its protection scheme. The OC relays are located at the beginning of each feeder lines to protect the system. These relays are denoted as R7, R3, R2, R6 and R4 respectively. The capability of the OC relays to protect the microgrid is assessed for grid-connected and islanded mode of operation. As shown in Table 1, for a sample of three-phase short circuit at Line 3 in both modes of operation, the OC relay are capable to clear the fault current contributions from the upstream sources but at the downstream side, DGs still feed the fault current to the fault point. The prolonged fault event due to the feeding effect by DG may damage some equipment associated with the faulted section. Therefore, a direction sensitive relay is required at the DG location to remove the feeding effect during fault.
environmental pollution and diminish the need for network expansions. The protection devices are set to have a coordi- nated operation to isolate faults with minimum impact on cus- tomers. When DG units are connected to a distribution network, the magnitude and direction of fault current will be changed. So, the coordination between the network protection devices may vanish  . Autorecloser-fuse miscoordination and relay–relay miscoordination can occur. Size of DG, location of DG, and type of DG (static or rotating machine) inﬂuence the
Distributedgeneration comprises of power generating units that use some of the latest technological innovations to produce few kilowatts to megawatts of power while being quite compact. DGs are usually owned by individuals and placed near electrical loads; independent power producers and electric utilities also own DGs . DGs have advantages such as being environmentally friendly, reduction of on-peak operating cost, and potential increase of service quality to the customer. Additionally, it is easier to place and install DG, as they are available in modular units; thus, leading to less time for construction and lower capital costs . The major issues in the integration of distributedgeneration systems are; frequency stabilization issues, voltage stabilization issues, intermittency of the renewables, power quality issues , and its negative effect on the distribution system protection such a relay mal-operation. The addition of DG to the system causes changes in the magnitude and direction of the power flow, as well as short-circuits current during fault conditions. The severity of the disturbance in the system depends on the size, location, the DG technology type, and the way they are connected to the distribution network .
As a reinforcement, the false tripping on healthy feeders may probably solved by using directional overcurrent relay for the circuit breaker , . One of the solutions regarding the fuse blowing is limiting the contribution of DG, instead of replacement or new settings , . This method is possible and does not require a great investment. The principle is that there is a margin of the fault current from DG sources for the loss of protectioncoordination.
for the PV array and in some conditions it would prove quite significant .Also, working in pu is more desirable than actual values the full conversion of the wind system to pu would be useful. The other way is to keep the model up to date with the technology. This means as science and engineering develop more efficient technology the system should be updated also. In the area of PV arrays technology is constantly changing and improving. As there are other power sources being considered for use in micro-grids there search and modelling of them will at some point be necessary. The sources being considered include fuel cells and batteries which provide electrical storage. They would need to go through the same process used to develop the other models, and then be connected into the micro-grid system.
It can be seen from Table 2 that LR = 0.4 provides the best average fitness value with a success rate of 90%, the second best is LR = 0.2 followed by LR = 0.6, both with success rates of 80%.The results for learning rates LR = 0.8 and LR = 1.0 yield relatively higher average fitness values compared to the learning rates LR = 0.2, 0.4, and 0.6. The worst average fitness value is provided by LR = 0.01 with 0% success rate, followed by LR = 0.05 with a success rate of 60%. The poor performances of LR = 0.01 and LR = 0.05 can be explained by the fact that at lower learning rates there is less exploitation of the best solution and therefore the algorithm tends to require more time to converge. At higher learning rates (i.e., LR = 0.8 and LR = 1), there is less exploration of the search space and therefore the algorithm tends to converge prematurely. Although for LR = 0.1, the average fit- ness value is slightly higher than those of LR = 0.2 - 0.8, it is the only learning rate that has a 100% success rate. This means this learning rate is more stable. The simulation results show that the learning rate has an impact on the performance of the PBIL. Therefore, a trade-off between exploration and exploitation is required for a good performance of PBIL.
Abstract— Coordination of directional overcurrent relays in power system networks with numerous interconnected networks in addition to the bidirectional power feed due to the implementation of various distributedgeneration resource becomes a very Complex task for protection engineers. The procedure of setting the directional relays for coordination manner requires load flow analysis, short circuit analysis, relay pairs list, and a protectioncoordination algorithm. This paper proposes integrated algorithms for directional overcurrent relays coordination in IEEE 8 bus interconnected system. The algorithms combined GA/GW/MF/SSA optimizers with the LINKNET algorithm for identifying the primary and backup relays and obtaining these relays settings. The most successful intelligent optimization algorithm has been validated in the directional overcurrent relay coordination in this paper.
Abstract: - Relay protection setting of substation plays a very vital role for power system safe operation. But in the recent years power demand has increase substantially while the expansion of the system has been severely limited due to abnormalities of Isolation of faulty areas by the protection system as a result of lack of effective coordination of the relay operation. The main objective of this paper is to design a computer based model using different characteristics equation of overcurrent relay (Standard Inverse, Very Inverse and Extremely Inverse) for determination of different relay parameters. This paper also present the relay setting and coordination of a 132/33kV typical substation with expected short circuit of 2044.5A and 800A at the respective busbars. Graphic user interphase (GUI) a subprogram of MATLAB is used. The results of the actual operating time and time multipiler setting (TMS) of different relay are determined.
In a radial system it is recommended to start the coordination from the relay nearest to the load toward the source. On the other hand, there is no such recommendation in a mesh system but arbitrary choose a start point and coordinate the relays. This might result to a bad coordination at the moment closing the mesh system, meaning the last relay which must be coordinated with the first relay that was chosen as start point do not satisfy the coordination idea. In other words, the first relay that was chosen as the start point fails to offer backup for the last relay that was to be coordinated with at the moment of closing the ring fed system. This is very common scenery, so if it happens one must start the coordination all over again from selecting a new start point. As a result, optimization algorithms were implemented to avoid the repetitive and extreme time consumption of coordinating a mesh system. This will be discussed in detail in chapter 3.
Abstract: DistributedGeneration (DG) has been growing rapidly in deregulated power systems due to their potential solutions to meeting localized demands at distribution level and to mitigate limited transmission capacities from centralized power stations. Penetration of DG into an existing distribution system has so many impacts on the system. Despite the benefits a DG will provide; it has a negative impact on the power system protection, thus affecting both reliability and stability of the system. This paper evaluates the impact of DG on the power protection systems with DG integrated in the systems. IEEE 33 Bus system was modelled in full operational details using ETAP. Protectioncoordination was carried out using Modified PSO. To investigate the impact of DG on the protection systems, different fault scenario have been simulated with and without DG installed. The fault current level, false tripping, unintentional islanding, and behavior of the existing protection system were investigated considering two scenarios. Case one was the integration of single DG while case two was the integration of two DGs. The type of DG integrated was solar photovoltaic. Simulation results revealed that the fault current level for a 3 phase fault at bus 27 for the system increases by 2.5% for case one and 24% for case two. There was unitentational islanding and false tripping as a result of the current contribution from the DG. The sequence of operation of the protective devices clearly showed that there was mis coordination of the protective devices.
Solutions to the impact of DG have been presented in  where the authors suggest the adoption of distance protection, in [12-14] where the authors propose the use of fault current limiters (FCLs) and in [14-16] where the authors suggest to use adaptive protection. The authors of [14, 15] have proposed to use to sets of protection settings, one for DG connected and one for DG not connected to the network, while the authors of  have proposed a scheme where the settings of overcurrentprotection relays are amended in real time based on the fault level and the DG connection status. A solution that caters for islanded operation has been proposed in [10, 17], where the authors demonstrate how a simple adaptive overcurrentprotection scheme with two setting groups, one for grid connected and one for islanded mode of operation may solve the problem. It appears that, as yet, no solution has been proposed to address the impact of ANM systems on network protection.
Based on the previous studies in voltage sag mitigation and distributedgeneration, most of researchers used optimized DG location to reduce losses and improve voltage profile. Other researchers mitigate sag by introducing DVR [3,18] (Dynamic Voltage Restorer) and STATCOM (Static Compensator) [20,22], the authors focused on the control procedure and used battery banks with limited energy stored not to use DGs or optimize the distributedgeneration . Another author used genetic algorithm optimization technique to mitigate voltage sag  but with many dropouts and disadvantages such as using combination of single phase DG and three phase DG which is not realistic to propose single phase DG with approximately 500 KW. In-addition the researcher used only general type of DG, the researcher applied three phase short circuit to simulate voltage sag too while single phase short circuit is frequently occurs, almost 80% , so both of them should be applied to the system. All the previously mentioned limitations are recovered in this study, this leads to better results and improved solutions. Other authors used different types of optimization techniques to reduce losses and improve the voltage profile [3,5,8,9] and many others in literature review not to mitigating voltage sag. Based on the literature, the majority of authors divided into two groups, some of them used DVR and STATCOM to inject active and reactive power at specific location. The others optimized DGs locations and size to reduce losses and improve voltage profile.
These DG sources are ordinarily set near utilization focuses and are included for the most part at the dissemination level. They are generally little in size (with respect to the force limit of the system in which they are put) and particular in structure. A typical methodology to discover the site of DG is to minimize the force loss of the system –. Another technique for putting DG is to apply decides that are regularly utilized as a part of sitting shunt capacitors in appropriation systems. A "2/3 tenet" is exhibited in  to place DG on an outspread feeder with consistently conveyed load, where it is recommended to introduce DG of roughly 2/3 limit of the approaching era at around 2/3 of the length of line. This principle is basic and simple to utilize, however it can't be connected specifically to a feeder with different sorts of burden conveyance, or to an arranged system. References  and  present force stream calculations to locate the ideal size of DG at every heap bus in an organized system accepting that each heap bus can have a DG source.
currents for adaptive relaying setting has been discussed. This technique is used to resolve relay mis-coordination problems under DER penetration in distribution system. Another technique has been discussed in , in which FCLs are connected in series with the DER and utility interconnection point to restore fault current levels to the original values (without DER). The FCL sizing prob- lem is formulated as a non-linear programming problem, where the main objective is to minimize changes in fault current levels due to the addition of DER in the distribu- tion systems. In [87, 88], multiple criteria such as the number of super conducting fault current limiter (SFCLs), fault current reduction and total operating time of the relays are considered for determining the optimal place- ment of SFCLs for protectioncoordination of relays in an electric power system with DERs . Fast switching time feature of solid state fault current limiter (SSFCL) is also utilised for quick blocking of fault current from DER in the distribution systems. Moreover, SSFCLs are cost-efficient solution for minimizing the protection effect of DER on the distribution systems. In , GA is utilised to determine the optimum number, location and size of SSFCLs required in the network for blocking the DER fault impact. Sung-Hun et al.  developed an experimen- tal model in which the application hybrid SFCL on protectioncoordination among the protective relays is investigated.
In this case, each protection zone corresponds with one of the transmission lines. As we know the fault immediately after the breaker will have the maximum fault current. So now as per the fault occurs in the network considered the achieved minimum time discrimination of 0.05 seconds. If TDS is based on this calculation, then it will be true for all other fault locations that a minimum time interval of 0.05 seconds is always provided. This will ensure proper coordination as well as selectivity. The system data and the pickup current values are provided in the Table I. The minimum allowed TDS is taken as 0.01 and upper bound is taken as 1.1 in steps of 0.01. The objective function weights W0 I shown in eq.1 were all set equal to one because the lines are short and their lengths are approximately equal.
Basically Fuel cell is energy conversation technology which converts chemical energy in to electrical energy directly. All the fuel cell technologies consume hydrogen which is received from fossil fuel and the oxygen from air. In the presence of catalyst, under monitored and controlled condition the hydrogen inside the fuel cell is oxidized. Then combines the hydrogen and oxygen to produce water. Fuel cell has many advantages with respect to fossil fuel generation including high efficiency, low pollution, very low noise, quick installation and re-usable heat output . However fuel cell has many drawbacks including high initial cost, maintenance skills required, fuel sensitivity and unproven track record. Mainly five types of Fuel cells are available which include phosphoric acid fuel cell (PAFC), proton exchange membrane fuel cell (PEMFC), alkaline fuel cells (AFC), molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) . Fig -6.Shows the basic structure of fuel cell.
This paper describe effect of DistributedGeneration on short circuit level. Distributedgeneration attracting in medium voltage transmission and distribution power system. As the Nonrenewable sources are on the way of exhausting, so we need to generate more electricity from renewable sources. These sources are used in distributedgeneration so there is more importance of distributedgeneration in power system. Insertion of DG has some impact on power system. This Paper deals with the evaluation of impact of DG on short circuit level of power system by simulating LG, LL and LLLG faults at different inception angles. The work presented in this paper consists of a two bus radial power system simulated in PSCAD/EMTDC software. Monitoring of fault current, load current and bus voltages is done in the simulation.
Initially, it is assumed that there is no generation previously connected. For the firm + non firm case, it is assumed that the maximum firm capacity has been connected. The non firm capacity is then allocated on top of the existing firm capacity. Two out of the five network sections analysed were not voltage constrained. These network sections were located in less rural areas, i.e. with higher load and short circuit levels. It was found that the short circuit level was the binding constraint in these cases and therefore non firm voltage access did not yield any further generation capacity. The other three network sections were all voltage constrained and had a rich wind resource, as would be typical all along the western coastline of Ireland. In these cases, non firm access yielded a significant amount of