retrieval system protection coordination of distribution...

Technical Journal of Engineering and Applied Sciences Available online at www.tjeas.com ©2013 TJEAS Journal-2013-3-23/3333-3345 ISSN 2051-0853 ©2013 TJEAS

Retrieval system protection coordination of distribution networks after the installation of

distributed generation resources with an intelligent algorithm

Ali Mirzakhani1, Mohammadali taghikhani2

Corresponding author email: [email protected]

ABSTRACT: The advantage of distribution generations (DGs), using DG in distribution network extremely increased. However, the presence distribution generation Conservation has resulted in problems such as lack of coordination. In this case, to solve this problem, proposed new method. In this case, In order to achieve better results in retrieving Coordination And reduce costs project include the cost of the Replacement of protective equipment, increase possible costs of power circuit breakers and reclosers and costs of fault current limiter. Also in this paper the limitation of changes & setting of protection device are removed (So CW, Li KK, Lai KT, Fung KY, 1997). For simulation of Coordination protective devises is using from DIGSILENT program and for Implementation optimization and intelligent algorithm is using MATLAB software. Finally, the proposed model on a distributed network is applied and the results are Presentation and analyzed. Keywords: coordination, Relay, DGs, Distributions networks.

INTRODUCTION

In recent years the use of distributed generation sources due to Economic and environmental benefits of greatly increased (El-Khattam W, Sidhu TS, 2008). Despite these benefits, many of the issues in this connection Resources to the power grid are created. Among most important the problem of Lack of coordination in the Distribution network protection system. Protection systems in distribution networks are generally radial; these networks regardless of DG Will design and coordinate. With the installation of DG Radial nature of the network is Loss and Short circuit levels, The currents lines and load flow in the network – each What factors are important in the design of protection systems - Changes and the previous protection coordination will not been (Tuitemwong K, Premrudeepreechacharn S, 2009). If the negative effects are not checks, the incorrect and inappropriate performance of protective devices, not distributed energy level, increasing and reliability of distributed systems greatly reduced (Hajizadeh A, Golkar MA. 2008). All papers contained in this paper different from what has been done in this field the following table describe some of these differences and indicators. Distributions networks protection The rules for the protection systems should be such that: The fault removed in minimum time. The aria that has no power because the protection devices are action be as small as possible. Recloser and relay setting and selection of fuses should be such that any coordination between pair of main and backup protection device per all short circuit conditions being established. For this purpose, we use from the Method of Six pairs of short circuit current Introduced in reference (Wu X, Lu Y, Du J. 2008). Six current pairs the relative currents of primary and backup relays are summarized below:

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Current pair No. 1 (CP#1) which means the fault is on the far end bus or line-end fault and lines outages are such that the current flowing through backup relay is maximum. Current pair No. 2 CP#2. The fault location of CP#2 is similar to CP#1 but the current through the primary relay is minimum. Current pair No. 3 is represented by CP#3 which consider close in fault but the lines outages are such that the current of backup relay is maximum. Current pair No. 4 is indicated by CP#4 which consider the fault to be at a point such that the current of the primary relay to be equal to the highest instantaneous element current setting Current pair No. 5 is shown by CP#5, if the high set instantaneous element exists, the relevant current of each P/B relay is the mean of current pairs 2&4. However if high set instantaneous element does not exist, then the mean of current pairs 2&3 is considered Current pair No. 6 is for CP#6, the fault point is the same as case 1&2 but the ratio of the backup relay

current to the primary relay current is minimum( J.A.Pecas Lopes, N.Hatziargyriou, J.Mutale, P.Djapic, N.Jenkin, 2007).

The rule of coordination between protections devices are in table II. In this table & paper: tb: The time performance of backup device. tm: The time performance of main device. tbf: The time of fast performance of backup device. tbd: The time of delay performance of backup device. tmf: The time of fast performance of main device. tmd: The time of delay performance of main device. MMC: Minimum melting curve of the fuse. TCC: Total time curve resolving fault.

Table 1. Comparison Conditions Used In this paper with other papers

Conditions considered in most papers

Conditions considered in this papers

Coordination includes only High current relays

Optimum coordination between fuse, relay &

recloser Using a pair of current

Short circuit Using six pair of current

Short circuit Size of Fault Current

Not to change the protection settings

Changing the protection settings with the

Size of fault Current Limiter

Setting resource capacity for Keeping the coordination

Determination protection Settings & size of Fault

Current limiter with Assuming To be determined

Resource capacity

Table 2. The rule of coordination between protection devices in distribution networks

Type of coordination Rule of coordination

Relay-Relay stb-tm > 0.3 second Relay-Recloser stb-tm > 0.3 second

Recloser-Recloser 0.95×tbf –tmf >0 second tbd-tmd > 0.3 second

Relay-Fuse stb-tm-TCC > 0.3 second Recloser-Fuse tbf – 0.75×tm-MMC <0

tbd-tm > 0.35 second Fuse-Fuse 0.75×tb-MMC-tm-TCC >0

Description of problem Figure I show a distribution generation source that connected to a network. A fault occurs in front of feeder that distribution generation source is connected.


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Figure 1. DG participated in short-circuit current

IDG & INET is respectively contribution of DG and main network to supply the short circuit current. According to this figure, IDG & INET before the installation of fault current limiter (ZFCL=0) is calculated as follows:

(1)

(2)

th N DGDG F

th N DG DG

DGNet F

th N DG DG

Z ZI I

Z Z Z

ZI I

Z Z Z

Thus, whatever source impedance is greater (production capacity lower) and whatever distance fault location from source is grater, IDG is lower. If short circuit current from main network and after install the DG is I

’NET

& INET, then we have:

'

( )1 (3)

( ) ( )

NET th N DG DG F DG

NET th N DG DG F DG DG F th N DG

I Z Z Z Z

I Z Z Z Z Z Z Z

By installing DG, the current of main network is decrees. However the fault current locations increase. Hence

the current of some protection devices increase and some of them decree; this operating result is lack of coordination of protection. For solve this problem use fault current limiter or (FCL). In this situation, INET and IDG and the ratio of INET on I

’NET can calculate from below formulation (IFOST, 2008):

(4)( )

( )(5)

( )

th N DGDG F

th N DG DG FCL

DG FCLNet F

th N DG DG FCL

Z ZI I

Z Z Z Z

Z ZI I

Z Z Z Z

'

( ) ( )1 (6)

( ) ( ) ( )

NET th N DG DG F DG FCL

NET th N DG DG F DG FCL DG F th N DG

I Z Z Z Z Z

I Z Z Z Z Z Z Z Z

According to above equations, ZFCL & IDG decrease INet decrease & ratio of INet on I

’Net decrease. This

means the problem of lack of coordination is improved.

PROPOSED METHODS In proposed method the size of ZFCL after installing DG So Determination in addition protection coordination, the costs of project also be minimized. These costs are: Cost of change protection device after installing DG Cost of increase the power of circuit breaker and recloser after installing DG Cost of installing of fault current limiter According to reference (Pecas Lopes JA, Hatziargyriou N, Mutale J, Djapic P, Jenkins N, 2007) we offer the cost of

inductive fault current limiter in reactance as follow:

0.0456

0.25

110000 (3.951 3.238 ) 6.5(7)

4130 (5.12 5.12 ) 6.5

X

FCL X

e XCost

e X

In this study, pre-installation of distributed generation source, for coordination of protective equipment used from bellow function:


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6

2 2

1 1 1 _ 2 _ _

1 11

. ( ) ( ( )) (8)pd mb

jN i N

i mb ij mb ij mb ij

i ij

O F t t t t

In which:

, i : Weighting coefficients.

mbN : Number of all main & backup devices.

pdN : Number of all protection devices.

it : Time duration of ith protection device.

mb ijt : Time difference between pairs of ith main and backup protection device in condition of jth pair

current and with the rule says in before section about coordination is calculated. With Installation DG, in addition to establishing Protection coordination, reduce create costs and are necessary for this reason the objective function is chosen as follows (Agheli A, Abyaneh HA, Mohammadi Chabanloo R, Hashemi Dezaki H. 2010):

2 _

6

2 2

1 1 _ 2 _ _

1 11

.

( ) ( ( )) (9)pd mb

CB recloser FCL

jN i N

i mb ij mb ij mb ij

i ij

O F Cost Cost

t t t t

In which

_CB recloserCost : cost of change in circuit breakers and reclosers for more power type of them

FCLCost : cost of FCL that before & after of installation of DG respectively is CTI=0.3 & CTI=0.285

I. Implemented method on sample network

The diagram of network that the method implement on this is shown in figure 3, also the information of this network is in table III.

Figure 2 . Show the algorithm and relation between two software in order to this purpose (IEEE Standard for Interconnecting

Distributed Resources with Electric Power Systems, IEEE Std, 2003.).


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Figure 3. Proposed method & represent connection Digsilent & Mathlab to each other In this network

Digsilent

part 1

•Definition of main & back up devices

Digsilent

part 2

• calculate pair of short circuit current & specify lines that be cut out for

worst condition

Digsilent

part 3

• calculate load flow, adjustment relays

maximum & minimum currents, definition the allowed area for fuses

selection & definition the parameter of PSO

intelligent algorithm

Mathlab

part 4

•Run Pso algoritm in M_File mode

Mathlab

part 5

• send best answer to Digsilent adjustments & stop the program

Digsilent

part 6

• adjustment TDS,PSM of relays & reclosers; Replacement new fuses & applying impedance of FCL

Digsilent

part 7

• calculate short circuit, set time of protection devices; calculate cost of changes

Digsilent

part 8

•Calculate the aim function or O.F function


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L are transmission lines, B are bus bars, R are over current relay, Rc are reclosers, Rcf are fast performance mode of reclosers and F are the fuses.

Table 3. information of above network Number of line Line reactance(Ω) Line

resistance(Ω)

L1 0.321 0.114 L2 0.384 0.137 L3 0.31 0.221 L4 0.031 0.022 L5 0.031 0.022 L6 0.301 0.221 L7 0.240 0.174 L8 0.156 0.801 L9 0.156 0.801

L10 0.156 0.801 L11 0.421 0.308 L12 0.320 0.114 L13 0.481 0.352 L14 0.360 0.264 L15 0.305 0.220 L16 0.361 0.264 L17 0.156 0.85

Distribution generation source are synchronization generator with 4.85 MVA power, 10.5KV output voltage, and 0.256 is transient reactance and 0.168 is super transient reactance in per unit. These DGs install in B3, B7 and B15. For accurate simulation we need fault current and the power of switches. Table IV show these parameters.

SIMULATIONS RESULT V.I Protection coordination of example network before install DG Before install DG for coordination the objective function in equation (8) is applied to example network. Results of outage switches and reclosers are in table IV

Table 4. power of outage swishes & reclosers Recloser or the relay that

order to switch power of outage switch(KA)

R2 25 R3 16 R4 12.5 R5 25 R6 16 Rc1 12.5 Rc2 8 Rc3 12.5

Results of running this program is setting relays, reclosers and selection proper fuses that show on tables 5, 6 &7. Current Setting of relays shown with Ib, fast performance current setting of reclosers shown with Ibf and delay performance current setting of reclosers shown with Ibd and all of unit is Ampere. Final output of program contain pair of short circuit, the time of starting main and backup protection devices and time duration performance of pair main and backup protection devices with “CTI=0.3second”. These result for two relay R1 & R2 are in table VIII.

Table 5. Relays setting Relay number Ib TDS

R1 2550.02 7.22 R2 1216.35 9.54 R3 816.20 9.53 R4 400.02 10.01 R5 1184.33 9.82 R6 776.12 9.36


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Table 6. Reclosers setting

Recloser number

Ibd TDS Ibf

Rc1 539 9.31 996 Rc2 337 8.01 340 Rc3 463 5.98 473

Table 7. Fuses setting

Fuse number

Nominal current

Fuse number

Nominal current

F1 100 F5 250 F2 100 F6 300 F3 100 F7 300 F4 300 F8 80

Table 8 have six column, column one as to pair of currents, column two and three as to short circuit current of backup (Ib) and main (Im) devices for the same current pair, column four and five as to performance time of backup and main protection device and finally the last column as to performance time duration that According to the rules in Table 2 is obtained. This column is very important in coordination problems. Optimal value for this column of table is the positive value near the zero and negative value in this column show the lack of coordination between main and backup protection devices.

Table 8. Result of current pair and duration time performance for R1 & R2 before install DG Current

pair Ib Im tb tm ∆t

1 12.98 13.20 1.649 0.801 0.555 2 6.69 6.63 2.721 1.044 1.383 3 23.89 24.01 0.723 0.410 0.017 4 - - - - - 5 14.01 15.39 1.288 0.655 0.333 6 13.30 13.17 1.649 0.801 0.557

The results are shown in Table 9 for the other pair devices. As is clear from Table 9, with running this program we don’t have any lack of coordination between protection devices before installing the DG.

Table 9. numbers and average of time duration for other devices Duration time performance

numbers average

∆t > 0 110 0.199579 ∆t < 0 0 0

Now, after installing DGs In this stage three distribution sources connected to B3, B7 and B15 bus bars without any changes in setting of protection devices and fuses. Changing in power of outage switches and reclosers is provided in table 10. According to this table the power of outage switch order from R2 and R5 relays should be increase and for other switches and reclosers last values are proper.

Table 10. Fault current front swishes and reclosers & power outage of them Relay that order to switch Outage power switch

R2 40 R5 40

Table 11 show result of currents pair and performance time duration for relays R1 & R2 after installing 3 DGs. Installing the DGs between two protection devices makes increase short circuit current device in front of source and decrease short circuit current other device at this situation there is possible to increase duration time between two devices. This condition observed for main-backup relay R1 & R2. The results for the other pair of the equipment are in table 12. According to this table we have totally 10 lack of coordination from installing DGs


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Table 11. short circuit current pair and duration performance time for pair device relay R1 & Relay R2 after installing DG Current

pair Ib Im tb tm ∆t

1 12.72 13.53 1.775 0.773 0.701 2 6.05 6.54 3.162 1.091 1.770 3 23.84 25.94 0.726 0.371 0.054 4 - - - - - 5 14.94 16.18 1.386 0.624 0.461 6 12.72 13.53 1.775 0.773 0.701

Table 12. numbers and average time duration for other devices Duration time performance

Numbers average

∆t > 0 110 0.199588 ∆t < 0 10 -0.012651

It is noticeable that all these lack of coordination related to the third pair, This is consistent that lacking of coordination in previous step (Table 8), the Values of time difference Considering the time interval coordination for third pair are very small and close to zero, so with installing DG possibility lack of coordination in third pair of current is more than other current pairs. installing resistive, inductive & inductive-resistive fault current limiter for coordination retrieval To relive the lack of coordination of protection devices was seen in the proviso section, installing resistive, inductive & inductive-resistive fault current limiter for coordination retrieval in this section. For select the impedance of these FCLs used various methods that the results are presented in the following at figure 4. It is noteworthy that after installing DGs the new CTI is 0.285second.

Figure4.

Determination the size of fault current limiter step by step At this method, select three FCL with equal sizes. Then step by step increase the size of FCLs as along as coordination is retrieval. Also in inductive-resistive FCLs, resistance and reactance considered to be equal. Figure 4 shows the increase of time duration of performance for a pair of devices that time duration of performance of them is negative. This figure shows the increases of any kind of FCLs. As can be seen in Fig 4, for inductive reactance FCL 5.45Ohm, for resistive FCL 7.5Ohm and for inductive-resistive FCL 6.489Ohm coordination is retrieval. Also observe that inductive FCLs type than resistive type with the equal impedance having more effect to coordination and reduce the effect of DGs. Determination the sizing of FCL with the PSO algorithm In this method, three FCLs impedance doesn’t select equal. Also for inductive-resistance FCLs the size of resistance and reactance for each FCL doesn’t select equal and cost of resistive FCL consider twice more than inductive FCL. In this method is used from PSO algorithm for find optimum impedance of FCLs. Coordination duration time as before reduced from 0.3 second to 0.285 second. In this situation the objective function is equation 10 as follows:


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1 2 3 1 2 32 ( ) (10)OF X X X R R R

Results of PSO algorithm for each kind of FCLs, According to the conditions stated are given in Table 13.

Table 13. the result of PSO algorithm for FCLs Number of FCL

& the Reactance or resistance of

them

Inductive type

Resistive type

Inductive-resistive

type

The reactance of first FCL

1.5008 - 2.1033

The resistance of first FCL

- 6.3698 0.013

The reactance of second FCL

7.6110 - 7.2503

The resistance of second FCL

- 8.2520 0.1110

The reactance of third FCL

6.9166 - 3.9991

The resistance of third FCL

0 5.8944 0.3166

With accuracy of this table shows that in third column, resistor of FCLs In comparison with reactance of them by PSO algorithm is smaller. Because in objective function, the cost of resistive FCL twice more than inductive kind is conceded and So what was seen previously the inductive FCLs compared to resistive one with equal impedance have more effect on retrieval coordination in protection devices. Also time duration of performance of protection devices that has been inconsistency for third pair, after installation any kinds of FCLs determined by PSO are in table 14. In this table can be seen that the time duration of performance of protection devices is more than 0.285second and the result is coordination. Also by attention in 2 ending rows of this table, the support for fast performance of recloser Rc2(Rc2F) from F2 & F3 fuses, In view of the coordination rule for Recloser - fuse coordination is set.

Table 14. time duration of performance of main-backup protection devices for third pair of current with installations any kind of FCLs resulted in PSO

Backup device

Main devic

e

t (of Three DG

without FCL)

t (of Three DG with FCL)

t ( of Three DG with

resistive FCL)

t ( of Three

DG with inductive FCL)

R2 R3 -0.0162 0.9162 0.7841 0.9161 R3 Rc1 -0.0123 0.7161 0.0244 0.7170 R5 R6 -0.0171 0.9211 0.7110 0.8391 Rc1 Rc2 -0.0316 0.1613 0.1622 0.1640 Rc2 F2 -0.0223 0.1241 0.1251 0.1263 Rc2 F3 -0.0223 0.1241 0.1251 0.1263 Rc3 F6 -0.0244 0.1292 0.1465 0.1511 Rc3 F7 -0.0248 0.1281 0.1442 0.1501

RC2F F2 -0.0042 0.0163 0.0163 0.0150 RC2F F3 -0.0046 0.0163 0.0163 0.0150

Determine sizes of FCLs and set protection devices by using PSO algorithm In this method use from inductive-resistive FCL. In addition, allow to change protection setting, because of this use from equal 11 for objective function (Chowdhury SP, Chowdhury S, Ten CF, Crossley PA, 2008):

2

1 2 3 1 2 3 1

1

6

2

1 _ 2 _ _

11

. ( 2 ( )) ( )

( ( )) (11)

pd

mb

N

i

i

ji N

mb ij mb ij mb ij

ij

O F X X X R R R t

t t t


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Also, F1 fuse replace with a directional relay. In this situation, new protection setting and the size of resistor and reactance of FCL is determining in somehow that In addition to the coordination of protective devices, the size of FCLs be as small as possible. Table 15 show the value that be selected for FCLs by PSO algorithm. As can be seen in this table, the PSO algorithm willingness to select small value for resistance and large value for reactance of FCLs. Because in this situation, the cost of resistor of FCL twice more than the reactance of that.

Table 15. the value of PSO algorithm for FCLs

Resistive-Inductive FCL Value and Result

Reactance of first FCL 1.4989 Resistance of first FCL 0.1108

Reactance of second FCL 5.0237 Resistance of second FCL 0.2987

Reactance of third FCL 3.9191 Resistance of third FCL 0.2155

The result for protection setting for relays and reclosers are shown in table 16, 17 & 18.

Table16. Relays setting The number of

relay Ib TDS

R1 2850 3.73 R2 1248 8.99 R3 1040 6.96 R4 400 10 R5 1280 9.05 R6 783 9.60 R7 120 6.03

Table 17. reclosers setting

The number of recloser

Ibd TDS Ibf

Rc1 610 8.02 1000 Rc2 378 7 407 Rc3 570 5.34 407

Table 18. Fuses selection result

The number of fuse Nominal current of fuse

F2 100 F3 100 F4 300 F5 250 F6 300 F7 300 F8 80

Table 18 shows that selection fuses comparison of last doesn’t have any changes. The cause of this problem is discretion of fuses. In addition, short-circuit currents and load current for this fuses are the most end protection devices, with installation DGs and FCLs fuses has less changes compare with other protection devices. Duration time performance of protection devices for third pairs after installation DGs by PSO, in table 19 shows new protection devices setting for relays and reclosers. It is seen in the last column of this table there are coordination between protection devices. Also Like the previous method, the bottom two rows of this table show necessary coordination in fast performance of recloser Rc2(Rc2F) from the F2 and F3 fuses with rule of recloser-fuse coordination setting.


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Table 19. Δt for third pair current with installation inductive-resistive FCL by results of PSO

Backup device

Main devic

e

t(without

DGs)

t (of Three DG

without FCL)

t ( of Three

DG with resistive-inductive

FCL)

R2 R3 0.00046 -0.01683 0.00204 R3 Rc1 0.00006 -0.01264 0.00223 R5 R6 0.00056 -0.01721 0.00112 Rc1 Rc2 -0.0000 -0.031111 0.00090 Rc2 F2 0.0000 -0.02271 0.00062 Rc2 F3 0.00004 -0.02271 0.00062 Rc3 F6 0.00050 -0.02441 0.00042 Rc3 F7 0.00062 -0.02427 0.00052

RC2F F2 0.00240 -0.00044 0.00078 RC2F F3 0.00240 -0.00044 0.00078

Determine impedance of inductive-resistive FCL and new set of protection devices with the costs of plan In final step, for retrieve protection coordination and determine the size of current FCLs, in additional to changes in protection setting, Relevant costs of the protection plan is also considered. These costs are considering FCLs and Potential costs of increase in power of switches and reclosers. Table 20, 21 & 22 shows the result of FCLs selection, relay and reclosers setting and select fuses by PSO algorithm. According to last methods, section FCLs by PSO are more inductive nature and like last methods the result of fuse selection hasn’t changed. Time duration performance of protection devices for third current pair, after installation these FCLs and applying new protection setting are in table 24 that for each device this time duration is 0.285 second.

Table 20. Result value of PSO for FCLs Resistive-Inductive FCL Value and Result

Reactance of first FCL 2.1900 Resistance of first FCL 0.0013

Reactance of second FCL 4.9815 Resistance of second FCL 0.2497

Reactance of third FCL 3.9903 Resistance of third FCL 0.4633

Table 21. Relays setting

The number of relay

Ib TDS

R1 2190 4.70 R2 1200 9.45 R3 865 8.71 R4 376 9.75 R5 1185 9.25 R6 712 9.40 R7 170 2.88

Table 22. reclosers setting

The number of recloser

Ibd TDS Ibf

Rc1 712 6.68 795 Rc2 366 8.12 575 Rc3 564 9.30 474


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Table 18. Fuses selection result The number of fuse Nominal current of fuse

F2 100 F3 100 F4 300 F5 250 F6 300 F7 300 F8 80

Table 19. Δt with installation inductive-resistive FCL by results of PSO with changing in protection setting Considering the

costs

Backup

device

Main devic

e

t(without

DGs)

t (of Three DG

without FCL)

t ( of Three DG

with resistive-inductive

FCL)

R2 R3 0.00046 -0.01683 0.00050 R3 Rc1 0.00006 -0.01264 0.00046 R5 R6 0.00056 -0.01721 0.000575 Rc1 Rc2 -0.0000 -0.031111 0.000530 Rc2 F2 0.0000 -0.02271 0.000455 Rc2 F3 0.00004 -0.02271 0.000455 Rc3 F6 0.00050 -0.02441 0.000684 Rc3 F7 0.00062 -0.02427 0.000780

RC2F F2 0.00240 -0.00044 0.00081 RC2F F3 0.00240 -0.00044 0.000825

COMPARISON OF DIFFERENT METHODS

As seen in the previous section, in all of the proposed methods, new time duration performance that was 0.285 second is establish. Table 25 shows the final costs of each above cited method. Maximum cost is for step by step method that leads to select three 6.5Ohm inductive-resistive FCL. Minimum costs is generated when the protection setting can also be changed by PSO algorithm that this condition can be seen in the last two columns in this table. Finally, the least Costs between the two columns of the table corresponds to the case that in objective function, all costs of switches and FCLs are be considered and this costs are in the last column of table.

CONCLUSIONS In this study, the effect of DG on the protection system is examined and observe that with installation this source, fault currents can be some changes that these changes leads to lack of coordination in protection system. To resolve this lack of coordination used fault current limiters (FCLs). To determine the size of FCLs, using various methods, which were divided into two categories. In first category, the protection setting has no changes and for determines the size of FCLs use from step by step and PSO algorithm. Secondly, allow changing the protection setting in order to retrieval protection coordination and also can optimum the costs of protection plan. We use from PSO algorithm to determine the impedance of FCLs and protection setting. These methods include the two-way, the first, the only change was in the protection settings. But in the second way, in additional to these changes, the costs of protection plan Include probable cost of increased power of switches and Reclosers and costs of FCLs were considered in the objective function. The raised method is applied to an example network. After installing the DGs Coordination time interval that previously was 0.3 second decrees to 0.285 second and observed that all of the above methods lead to protection coordination. Finally To compare the proposed method, the cost of this method was compared and seen the less costs is in method which we can changes in protection devices setting and also total costs exist in objective function.


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Table20.

Kind of FCL and

costs

Cost of(Three 5.5Ohm inductive

FCL) $

Cost of(Three 7.5Ohm resistive

FCL) $

Cost of(Three 6.5Ohm

inductive-resistive

FCL) $

Cost of(three inductive

FCLs specified by PSO)

$

Cost of(three resistive


$

Cost of(three

inductive-resistive


$

Cost of(three

inductive-resistive

FCLs specified by

PSO and setting

changes) $

Cost of(three inductive-resistive FCLs specified by PSO and setting

changes with consideration

costs) $

Inductive FCL1

15.73744 0 14.38733 6.57504 0 8.345959 6.580834 8.880592

Resistive FCL1

0 36.07404 28.77466 0 33.55945 0.1366873 1.149853 0.0136887

Inductive FCL2

15.73744 0 14.38733 18.16353 0 17.75021 15.06415 15.00068

Resistive FCL2

0 36.07404 28.77466 0 37.76566 1.151901 3.031174 2.549317

Inductive FCL3

15.73744 0 14.38733 17.3609 0 13.30874 13.15644 13.29632

Resistive FCL3

0 36.07404 28.77466 0 32.47448 3.196975 2.210484 4.6054

Costs of replace

switches 0 0 0 3.8408 0 1.9204 3.8408 0

Total cost 47.21232 108.2221 129.486 45.94027 103.7996 45.81086 45.03373 44.34599

REFERENCES

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