JP2014135812A - Distribution line different system loop switching propriety discrimination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distribution line different system loop switching propriety discrimination method which allows for easy and safe propriety discrimination in the different system loop switching of distribution line.SOLUTION: When performing loop switching by closing a switch at the loop point of two distribution lines having different substations of high-order system, the loop point phase difference at the loop point of two distribution lines is calculated, the loop allowable phase difference at the loop point is calculated, and then propriety of loop switching is determined by comparing the loop point phase difference and loop allowable phase difference. The loop point phase difference is determined by adding a high-order system phase difference obtained by angle synthesis of phase difference at the breaker release point of a substation in the high-order system, and the distribution system phase difference at the loop point of two distribution lines.

Description

  The present invention relates to a method for determining whether or not different distribution line loop switching is possible when a switch is inserted at the end of two distribution lines having different upper systems to perform loop switching.

  When switching the uninterruptible loop by inserting a switch linked to the end of two distribution lines with different upper systems, loop cross current flows over the existing load current in the loop distribution line, This should be avoided because the current may exceed the allowable distribution line value and the operating settling value of the substation overcurrent relay. This is because the distribution equipment is damaged when the current in the loop exceeds the allowable distribution line current value, and when the current in the loop exceeds the operation set value of the substation overcurrent relay, the circuit breaker is activated by the overcurrent relay operation. This is due to a trip blackout.

  For this reason, when switching between different loops is considered, it is determined whether switching is possible while comparing the calculated value and the actual measured value by calculating the phase difference of the loop points and using the loop checker (phase angle measuring device) in advance. It is carried out. Regarding the on-site measurement of the loop point by the loop checker, depending on the on-site power distribution equipment, the loop checker may not be physically attached, and the on-site measurement operation may be canceled due to bad weather.

  Therefore, when switching between different system loops, there is one in which the power flow P applied to the transmission system having a voltage class of 66 kV is acquired as upper system information of the loop target line, and the phase difference calculation of the loop points is performed ( For example, see Patent Documents 1 and 2).

JP 2009-55705 A JP 2012-90386 A

  However, in Patent Documents 1 and 2, when calculating the phase difference of the loop point, it is necessary to acquire the power flow P applied to the power transmission system having a voltage class of 66 kV as the upper system information of the loop target line. Since the power flow P of the host system is not data managed by the control station, only the data managed by the control station is insufficient when calculating the phase difference of the loop points.

  For this reason, it is necessary to obtain information on a power supply station that has jurisdiction over the host system, and it is necessary to calculate the phase difference of the loop points in consideration of the power flow P that changes from moment to moment. Therefore, the calculation load concerning this increases, and considerable scale and introduction cost are required for systemization.

  Also, in Patent Documents 1 and 2, the always-off part for measuring the phase difference (loop angle) of the upper system is a simple system with only one place, but in the actual upper system, the power substation breaker When there are a plurality of constantly cut locations, and there are a plurality of constantly cut locations, the calculation of the phase difference (loop angle) of the upper system becomes complicated.

  As described above, in Patent Documents 1 and 2, since the power flow P of the upper system of the loop target line is used in the phase difference calculation process of the loop point, the power flow P of the power station that has jurisdiction over the upper system is used. It is necessary to obtain information, and most of the actual high-order systems have a plurality of power supply substation circuit breakers that are always cut off. It is necessary to calculate the phase difference.

  An object of the present invention is to provide a method for determining whether or not a distribution line different system loop can be switched safely and easily.

  According to the first aspect of the present invention, the method for determining whether or not a different distribution system loop can be switched is performed when a switch is inserted at a loop point of two distribution lines with different substations in the upper system to switch the loop. A distribution line different system loop that calculates a loop point phase difference at a loop point, calculates a loop allowable phase difference at the loop point, and determines whether loop switching is possible or not by comparing the loop point phase difference and the loop allowable phase difference In the switchability determination method, the calculation of the loop point phase difference is performed by calculating the phase difference of the circuit breaker open location of the upper system substation and the upper system phase difference obtained by angle synthesis and the distribution system of the loop points of the two distribution lines. It is characterized by being obtained by adding the phase difference.

  According to a second aspect of the present invention, there is provided a method for determining whether or not a distribution line different system loop can be switched. In the first aspect of the invention, a safety margin in consideration of a calculation error of the loop point phase difference is prepared in advance. The determination of availability is performed by obtaining a safety margin addition loop point phase difference obtained by adding the safety margin to the loop point phase difference, and when the safety margin addition loop point phase difference is equal to or less than the loop allowable phase difference, the loop It is characterized by determining that switching is possible.

  A method for determining whether or not a distribution line different system loop can be switched according to the invention of claim 3 is characterized in that, in the invention of claim 2, the maximum value of the error between the calculated value of the loop point phase difference and the actually measured value is defined as the maximum error. An average value of errors between the calculated value of the phase difference and the actual measurement value is acquired in advance as an average error, and the safety margin is determined as follows according to the polarity of the loop point phase difference. .

(1) When the polarity of the loop point phase difference is positive When the difference between the loop allowable phase difference of the non-reference distribution line that is not the reference phase of the two distribution lines and the loop point phase difference is smaller than the maximum error Uses the maximum error as the safety margin, and when it is larger than the maximum error, the average error as the safety margin.

(2) When the polarity of the loop point phase difference is negative When the difference between the loop allowable phase difference of the reference distribution line of the reference phase of the two distribution lines and the loop point phase difference is smaller than the maximum error The maximum error is set as the safety margin, and when the maximum error is larger than the maximum error, the average error is set as the safety margin.

  According to the invention of claim 1, the upper system phase difference obtained by angle-combining the phase difference of the circuit breaker open part (always cut part) of the upper system substation, and the distribution system phase difference between the loop points of the two distribution lines Is added to obtain the loop point phase difference, so that switching between different systems loops of the distribution line can be determined whether or not switching is possible without performing on-site measurement by a loop checker (phase angle measuring device). Therefore, it is possible to reduce field work and improve efficiency. In addition, it is not necessary to collect the power flow P of the upper system in calculating the loop point phase difference, and the upper system information is regarded as the phase difference of the upper system with the phase difference (loop angle) of the constantly cut location, and 66 kV By omitting the power flow P applied to the transmission system from the calculation, a simple and inexpensive calculation can be achieved.

  According to the second aspect of the present invention, a safety margin in consideration of the calculation error of the loop point phase difference is prepared in advance, and whether or not the loop can be switched is determined by adding a safety margin to the loop point phase difference. Since it is determined whether or not loop switching is possible based on the phase difference of the addition loop points, the safety of loop switching can be ensured.

  According to the invention of claim 3, the maximum value of the error between the calculated value of the loop point phase difference and the actually measured value is taken as the maximum error, and the average value of the error between the calculated value of the loop point phase difference and the actually measured value is taken as the average error. The safety margin is either the maximum error or the average error based on the polarity of the loop point phase difference and the difference between the loop allowable phase difference and the loop point phase difference of each of the two distribution lines. Therefore, when the loop point phase difference has a margin with respect to the loop allowable phase difference, the range in which loop switching is possible can be expanded.

The flowchart which shows an example of the process of the distribution line different system loop switching possibility determination method which concerns on embodiment of this invention. The distribution diagram in the embodiment of the present invention is an example of a system that is a target of switching between different distribution line loops, and is a system diagram in the case where a single circuit breaker opening location of the upper system substation is single. The distribution diagram in the embodiment of the present invention, which is another example of the system that is the target of switching the different distribution line loops, is a system diagram in the case where there are a plurality (two) of circuit breaker open locations in the upper system substation. The system diagram in case the A substation of the reference | standard of FIG. 3 becomes a circuit breaker open location. The system diagram in case the A substation of the reference | standard of FIG. 2 is a circuit breaker open location. FIG. 6 is an explanatory diagram of a loop allowable phase difference | θA ′ | and a loop allowable phase difference | θB ′ | according to the polarity of the loop point phase difference θx. The flowchart which shows an example of the other process of the distribution line different system loop switching possibility determination method which concerns on embodiment of this invention. The flowchart which shows an example of the safety margin determination process in the safety tolerance determination process of step S9A of FIG. The flowchart which shows another example of the safety margin determination process in the safety tolerance determination process of step S9A of FIG. FIG. 8 is a detailed view of step S10A of FIG. Relationship between safety margin addition loop point phase difference θi (= | θx | + | θα |) and loop allowable phase difference | θA '| and loop allowable phase difference | θB' | according to polarity of loop point phase difference θx FIG. The system diagram in the case of calculating the loop point phase difference in consideration of the power flow P applied to the 66 kV transmission system in the comparative example of the present invention. Explanatory drawing of loop allowable phase difference | (theta) A '|, | (theta) B' |, safety tolerance addition loop point phase difference (theta) i, and loop point phase difference (theta) x of the whole loop at the time of using the a distribution line in a comparative example. The system diagram in the case of calculating the loop point phase difference without taking into consideration the power flow P applied to the 66 kV transmission system in the embodiment of the present invention.

  First, the background to the present invention will be described. While accumulating the track record of different system loop switching in the actual system, at the loop point of the two distribution lines, comparing the calculated phase difference and the measured value of the loop checker (phase angle measuring device), In calculating the phase difference of the loop point of the electric wire, it was verified which part of the loop target line has a large phase difference generation rate. According to it, the phase difference of the upper system, the phase difference of the distribution substation bank, the phase difference of the distribution line is large, and the phase difference of the 66 kV transmission line has a small impedance value, so the generation ratio of the phase difference is also very small Thus, even if omitted, it was found that there was a slight error.

  Furthermore, in the actual upper system, most of the systems have a plurality of always-off locations of circuit breakers in power substations. For this reason, we will adopt a method that can calculate even if there are multiple phase differences (loop angles) in the upper system, so that it is possible to determine whether or not the distribution system can be switched between different system loops on the desk by safe, simple and inexpensive means. did.

  Therefore, in the present invention, when calculating the phase difference of the loop point, in order to make the load required for the calculation as simple as possible, the upper system information is the phase difference (loop angle) of the always-off part of the circuit breaker of the upper system substation (power supply substation). ) Is used as a phase difference for the upper system, and a simple calculation is realized by omitting the power flow P applied to the 66 kV transmission system from the calculation. As a result, it is not necessary to collect the power flow P that changes from time to time and to perform calculation in consideration of the power flow P applied to a complicated system.

  Furthermore, even if there are multiple phase differences in the upper system depending on the system status, the composite value of the phase difference in the upper system is obtained by angle synthesis calculation, and the distribution system level from the distribution substation bank to the distribution line loop point is calculated. The phase differences were summed to derive the loop point phase difference.

  Also, the safety margin is determined using the maximum value (maximum error) and average value (average error) of the error between the measured value and the calculated value of the past history, and the safety margin is calculated as the calculated loop point phase difference. The safety margin addition loop point phase difference obtained by the addition is determined based on whether or not the loop can be switched based on whether or not the loop point phase difference is within the range of the loop allowable phase difference at the time of the loop as seen from the distribution line allowable current. judge. Therefore, it is possible to determine whether or not the different system loop switching of the distribution line is safe, simple, and inexpensive.

  Embodiments of the present invention will be described below. FIG. 1 is a flowchart showing an example of a process of a method for determining whether or not a distribution line different system loop can be switched according to the embodiment of the present invention, and FIG. 2 shows an example of a system which is a target of distribution line different system loop switching in the embodiment of the present invention. FIG. 3 is another example of a system that is a target of switching a distribution line different system loop in the embodiment of the present invention, and is a diagram of the upper system substation. It is a systematic diagram in case a circuit breaker open location is multiple (2 places).

  In FIG. 1, first, data acquisition processing is performed for the upper system of the distribution line and the distribution system to be loop point switched (S1). Hereinafter, the case of the system shown in FIG. 2 will be described.

  In FIG. 2, it is assumed that the loop point X of the power distribution system is a loop point to be switched. The loop point X of the distribution system is open, the load current Ia is supplied from the F distribution substation bank 12f to the a distribution line 11a, and the load current Ib from the C distribution substation bank 12c to the b distribution line 11b. Is supplied. The F distribution substation bank 12f is supplied with electric power from the upper system A substation 13a, and the C distribution substation bank 12c is supplied with electric power from the upper system B substation 13b. The circuit breaker 14a of the A substation 13a is closed, and the circuit breaker 14b of the B substation 13b is open. Black is closed and white is open.

  In step S1 of FIG. 1, as upper system information, the phase difference .theta.AB of the always-on part of the circuit breaker 14a of the A substation 13a, the phase difference .theta.BA of the normally-off part of the circuit breaker 14b of the B substation 13b, and the A substation 13a. The upper system impedance% Ze and the upper system impedance% Zd of the B substation 13b are acquired. The phase difference .theta.AB at the constantly entering position of the circuit breaker 14a in the A substation 13a and the phase difference .theta.BA at the constantly disconnected position of the circuit breaker 14a in the B substation 13b are the phase differences (loop angles) of the normally disconnected positions of the circuit breakers 14a and 14b. ) Is obtained from the substation system in the control station via the synchronous detection relay, and this is used as the phase difference (loop angle) for the upper system.

  Further, as the distribution system information, the bank current If and the bank impedance% Zf of the F distribution substation bank 12f are acquired, and the bank current If is converted into the active power Pf (P = √3 · V · If · cos θ). Similarly, the bank current Ic and the bank impedance% Zc of the C distribution substation bank 12c are acquired, and the bank current Ic is converted into the active power Pc (P = √3 · V · Ic · cos θ).

  Furthermore, the load current Ia and the distribution line impedance% Za of the a distribution line 11a are acquired as the distribution system information, and the load current Ia is converted into the active power Pa (P = √3 · V · Ia · cos θ). Similarly, the load current Ib and the distribution line impedance% Zb of the b distribution line 11b are acquired, and the load current Ib is converted into the active power Pb (P = √3 · V · Ib · cos θ).

  Next, a reference for the loop target is set (S2). For example, the upper system A substation 13a is set as the upper system reference substation, and the a distribution line 11a is set as the reference. As a result, the phase difference θAB at the always-on portion of the circuit breaker 14a of the A substation 13a is set as a reference phase, and the phase difference θBA at the constantly-cut portion of the circuit breaker 14b is set as a comparison phase.

  Next, it is determined whether there are a plurality of phase differences at the breaker opening locations of the upper system substation (S3). In the case of FIG. 2, the circuit breaker opening location is the circuit breaker 14b, and the phase difference of the circuit breaker opening location of the upper system substation is single (one location). On the other hand, in the case of FIG. 3, the circuit breaker opening locations are the circuit breakers 14b and 14c, and the phase difference of the circuit breaker opening locations of the upper system substation is plural (two locations).

  If it is determined in step S3 that there are a plurality of phase differences at the circuit breaker opening location, the higher system phase difference calculation process K1 is performed (S4).

  In the upper system phase difference calculation process K1, the upper system phase difference θ0 is obtained by angle synthesis using the following equation (1).

θ0 = reference phase difference θAB− {first comparison phase difference θBA−second comparison phase difference θCB}
= ΘAB− {θBA−θCB} (1)
The phase difference θAB is the reference phase difference θAB at the place where the circuit breaker 14a of the A substation 13a is always entered (referenced to the A substation 13a). The phase difference θBA at the location (referenced to the B substation 13b) and the second comparison phase difference θCB are the phase difference θCB at the location where the circuit breaker 14c of the C substation 13c is always cut off (referenced to the C substation 13c).

  Here, in the case of FIG. 3, since the circuit breaker 14a is turned on, the phase between the A substation 13a and the B substation 13b is in phase, and the reference phase difference θAB is zero. Further, when the second comparison phase difference θCB is expressed with reference to the C substation 13c, −θBC is obtained. Therefore, the first comparison phase difference θBA−the second comparison phase difference θCB is θBA − (− θBC) = θBA + θBC = θAC. Therefore, in the case of FIG. 3, the equation (1) is expressed by θ0 = −θAC.

  Also, as shown in FIG. 4, the breaker 14a of the reference A substation is open, the breaker 14b of the non-reference B substation is closed, and the breaker 14c of the non-reference C substation is closed. Even when it is open, there are multiple (two) phase differences at the breaker open locations of the upper system substation.

  In this case, since the circuit breaker 14b is turned on, the B substation 13b and the A substation 13a are in phase and the first comparison phase difference θBA is zero. Further, when the second comparison phase difference θCB is expressed with reference to the C substation 13c, −θBC is obtained. From this, in the case of FIG. 4, the equation (1) is expressed by θ0 = θAB + θBC = θAC.

  If it is determined in step S3 that the circuit breaker opening portion has a single phase difference, a higher-system phase difference calculation process K2 is performed (S5).

  The upper system phase difference calculation process K2 is also obtained by angle-synthesizing the upper system phase difference θ0 according to the above expression (1), but with the expression (2) when there is no second comparison phase difference θCB in expression (1) Become.

θ0 = reference phase difference θAB−first comparison phase difference θBA
= ΘAB−θBA (2)
As shown in FIG. 2, when the breaker open location is the breaker 14 b of the non-reference B substation 13 b and the breaker 14 a of the reference A substation 13 a is closed, the acquired phase difference is This is the first comparison phase difference θBA at location B. Further, since the circuit breaker of the reference substation A is closed, the reference A substation 13a and the B substation 13b are in phase and the reference phase difference θAB is zero. As a result, the upper system phase difference θ0 is (−θBA) obtained by reversing the sign of the first comparison phase difference θBA of the substation B from the equation (2).

  On the other hand, as shown in FIG. 5, when the breaker open location is the reference A substation 13a and the non-reference B substation breaker 14b is closed, the acquired phase difference is the reference A substation. This is the reference phase difference θAB at the point 13a. Further, since the circuit breaker 14b of the non-reference B substation 13b is closed, the non-reference B substation 13b and the reference A substation 13a are in phase, and the first comparison phase difference θBA is 0. Become. As a result, the higher system phase difference θ0 is the reference phase difference θAB of the reference A substation 13a from the equation (2).

  Thus, the higher system phase difference θ0 is obtained by angle-combining the phase differences of the circuit breaker open locations of the upper system substation.

  Next, the loop point phase difference θx of the entire loop when linked at the loop point X of the distribution line ab is obtained (S6). As shown in the equation (3), the loop point phase difference θx is obtained by adding the phase difference Δθ of the distribution system to the higher system phase difference θ0.

θx = θ0 + Δθ (3)
The phase difference Δθ of the distribution system is a phase difference from the distribution substation banks 12f, 12c of the distribution system to the loop point X. As shown in the equation (4), the loop point X from the F distribution substation bank 12f Is obtained as a difference between the reference phase θa of the reference a distribution line 11a leading to and the comparison phase θb of the non-reference b distribution line 11b extending from the C distribution substation bank 12c to the loop point X.

Δθ = reference phase θa−comparison phase θb
= Θa−θb (4)
The reference phase θa is obtained by the following equation (5), and the comparison phase θb is obtained by the following equation (6). In addition, in the formulas (5) and (6), the case where the reference capacity of the transmission line is 10 MVA is shown.

θa = (Pf ·% Zf + Pa ·% Za) / 1000 (5)
θb = (Pc ·% Zc + Pb ·% Zb) / 1000 (6)
Then, when the equation (4) is substituted into the equation (3), the loop point phase difference θx of the entire loop is expressed by the following equation (7).

θx = θ0 + Δθ
= Θ0 + (θa−θb) (7)
Thus, the calculation of the loop point phase difference θx is based on the phase difference from the upper system phase difference θ0, which is an angle composition of the phase difference of the circuit breaker opening of the upper system substation, and the phase difference from the distribution substation bank to the loop point. It is obtained by adding a certain distribution system phase difference Δθ.

  Next, the loop impedance of the loop formed when the loop point is closed is calculated (S7). This loop impedance% ZL is obtained by the following equation (8).

% ZL =% Za +% Zb +% Zc +% Zd +% Ze +% Zf (8)
That is, the distribution line impedance% Za,% Zb, bank impedance% Zc,% Zf, upper system impedance% Zd,% Ze of the loop formed when the loop point is closed are obtained in total.

  On the other hand, the loop allowable current viewed from the distribution allowable current of the a distribution line 11a and the b distribution line 11b is calculated (S8). The loop allowable current IA of the a distribution line 11a is the allowable current flowing through the a distribution line 11a when the loop point is closed, and the loop allowable current IB of the b distribution line 11b is b when the loop point is closed. This is the allowable current flowing through the distribution line 11b.

  When the a-distribution line short-time allowable current Iu and the distribution-line load current Ia are assumed, the loop-distribution current IA of the a-distribution line 11a is expressed by equation (9), and the b-distribution line short-time allowable current Iu and the distribution-line load current Assuming that it is Ib, the loop allowable current IB of the b distribution line 11b is expressed by equation (10).

IA = Iu-Ia (9)
IB = Iu-Ib (10)
Then, the loop allowable phase difference is calculated based on the loop allowable current IA of the a distribution line 11a and the loop allowable current IB of the b distribution line 11b (S9). That is, the loop allowable currents IA and IB are converted into loop allowable phase differences | θA ′ | and | θB ′ |. The loop allowable phase difference | θA ′ | is a threshold value when the loop point phase difference θx is negative with respect to the reference a distribution line 11a, and the loop allowable phase difference | θB ′ | On the other hand, this is a threshold value when the loop point phase difference θx is positive.

  The loop allowable phase differences | θA ′ | and | θB ′ | are expressed by the following equations (11) and (12).

| ΘA ′ | = IA ×% ZL / 1520 (11)
| ΘB ′ | = IB ×% ZL / 1520 (12)
In the equations (11) and (12), the line voltage of the distribution line is 6.6 kV, and the reference capacity of the transmission line is 10 MVA.

  Then, when the loop allowable phase differences | θA ′ | and | θB ′ | are obtained, the loop availability determination is performed based on the loop allowable phase difference result (S10). By comparing the loop point phase difference θx of the loop point with the loop allowable phase difference | θA '| and | θB' | seen from the distribution line allowable currents IA and IB, the loop point phase difference θx of the loop point is within the allowable range. Satisfying conditional expressions are derived as the following expressions (13) and (14).

When θx is negative, | θA ′ | ≧ | θx | (13)
When θx is positive, | θB ′ | ≧ | θx | (14)
FIG. 6 is an explanatory diagram of the loop allowable phase difference | θA ′ | and the loop allowable phase difference | θB ′ | according to the polarity of the loop point phase difference θx. When the loop point phase difference θx is positive with respect to the reference phase difference θa of the distribution line 11a, it is determined that loop switching at the loop point is possible if | θx | To do. Similarly, when the loop point phase difference θx is negative with respect to the phase difference θa of the distribution line 11a, loop switching at the loop point is possible if | θx | is in the range of | θA ′ | Is determined.

  In the above description, whether or not loop switching is possible is determined by comparing the loop point phase difference θx of the loop point with the loop allowable phase differences | θA ′ | and | θB ′ | Judgment is made based on whether or not the allowable range is satisfied. However, a safety margin | θα | considering the calculation error of the loop point phase difference θx is prepared in advance, and whether or not loop switching is possible is determined by the loop point. The safety margin addition loop point phase difference θi (= | θx | + | θα |) obtained by adding the safety margin | θα | to the phase difference θx, and the safety tolerance addition loop point phase difference θi is the loop allowable phase difference. When | θA ′ | and | θB ′ | or less, it may be determined that loop switching is possible.

  FIG. 7 is a flowchart showing an example of another process of the method for determining whether or not a distribution line different system loop can be switched according to the embodiment of the present invention. Steps S9A and S9B are added to the example shown in FIG. When the safety tolerance addition loop point phase difference θi is less than or equal to the loop allowable phase difference | θA ′ | and | θB ′ |, it is determined that loop switching is possible. The same steps as those in the example shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

  In FIG. 7, first, after obtaining the loop allowable phase differences | θA ′ | and | θB ′ | in step S9, a safety margin determination process for determining the safety margin | θα | is performed (S9A). FIG. 8 is a flowchart showing an example of the safety margin determination process. The measured value and calculated value of the loop point phase difference θx are stored in advance (T1). For example, the measured value and the calculated value of the loop point phase difference θx at each loop point of two distribution lines with different substations in the upper system are stored. At each loop point, a plurality of actually measured values and calculated values having different dates and times may be accumulated. Next, an error between the measured value and the calculated value of the loop point phase difference θx at each accumulated loop point is calculated, and the maximum value of the error at each loop point is obtained as the maximum error (T2). The maximum error is set as a safety margin (T3).

  Next, a safety margin addition loop point phase difference θi obtained by adding the safety margin | θα | determined in step S9A to the loop point phase difference θx is obtained by the following equation (15) (S9B).

θi = | θx | + | θα | (15)
Here, in FIG. 8, the maximum value (maximum error) of the error at each loop point is the safety margin | θα |, but as shown in FIG. 9, the polarity of the loop point phase difference θx, the two distribution lines Based on the difference between each loop allowable phase difference | θA ′ |, | θB ′ | and the loop point phase difference θx, either the maximum error or the average error of each loop point is selected. Also good.

  FIG. 9 is a flowchart showing another example of the safety margin determination process. Similar to step T1 in FIG. 8, the measured value and calculated value of the loop point phase difference θx are stored in advance (U1). Next, an error between the actually measured value and the calculated value of the loop point phase difference θx at each accumulated loop point is calculated, and the average value of the error at each loop point is calculated with the maximum value of the error at each loop point as the maximum error. The value is obtained as an average error (U2).

  Then, it is determined whether the polarity of the loop point phase difference θx is positive (+) (U3). When the polarity of the loop point phase difference θx is positive (+), whether the difference between the loop allowable phase difference | θB ′ | and the loop point phase difference | θx | Is determined (U4). When the difference is equal to or smaller than the maximum error εmax, the maximum error εmax is set as a safety margin | θα | (U5). On the other hand, when the difference between the loop allowable phase difference | θB ′ | and the loop point phase difference | θx | of the non-reference distribution line is larger than the maximum error εmax in the determination in step U4, the average error εave is determined as the safety margin | θα | (U6).

  On the other hand, if the polarity of the loop point phase difference θx is negative (−) in the determination of step U3, the difference between the loop allowable phase difference | θA ′ | and the loop point phase difference | θx | Is less than or equal to the maximum error εmax (U7). When the difference is equal to or smaller than the maximum error εmax, the maximum error εmax is set as the safety margin | θα | (U8). On the other hand, when the difference between the loop allowable phase difference | θA ′ | and the loop point phase difference | θx | of the reference distribution line is larger than the maximum error εmax in the determination of step U7, the average error εave is set as the safety margin | θα | (U9).

  As described above, when the loop point phase difference θx has a margin with respect to the loop allowable phase differences | θA ′ | and | θb ′ |, the difference is larger than the maximum error εmax. Let θα |. Therefore, the range in which loop switching is possible can be expanded. Similarly, in the case of the safety margin | θα | obtained by the processing of FIG. 9, the safety tolerance addition loop point phase difference θi (= | θx | + | θα |) is obtained by the above equation (15).

  FIG. 10 shows details of step S10A in the case where the loop availability determination is performed using the safety margin addition loop point phase difference θi (= | θx | + | θα |) obtained in the process of step S9B in this way. FIG.

  First, it is determined whether the polarity of the loop point phase difference θx is positive (+) (V1). When the polarity of the loop point phase difference θx is positive (+), the safety tolerance addition loop point phase difference θi (= | θx | + | θα |) is less than or equal to the loop allowable phase difference | θB '| Is determined (V2). When the safety margin addition loop point phase difference θi is equal to or less than the loop allowable phase difference | θB ′ | of the non-reference distribution line, it is determined that loop switching is possible without taking any special measures (V3). On the other hand, when the safety margin addition loop point phase difference θi is larger than the loop allowable phase difference | θB ′ | of the non-reference distribution line in the determination of step V2, it is determined that loop switching is not possible, and the expression (16) is satisfied. (V4). As countermeasures satisfying the equation (16), the load connected to the distribution line is switched to another distribution line, or the distribution substation bank is moved to one side.

| ΘB ′ | ≧ θi = (| θx | + | θα |) (16)
On the other hand, when the polarity of the loop point phase difference θx is negative (−) in the determination of step V1, the safety margin addition loop point phase difference θi (= | θx | + | θα |) is the loop tolerance of the reference distribution line. It is determined whether or not the phase difference is equal to or smaller than | θA ′ | (V5). When the safety margin addition loop point phase difference θi is equal to or smaller than the loop allowable phase difference | θA ′ | of the reference distribution line, it is determined that loop switching is possible without taking any special measures (V6). On the other hand, when the safety margin addition loop point phase difference θi is larger than the loop allowable phase difference | θA ′ | of the reference distribution line in the determination of step V5, it is determined that loop switching is not possible, and the expression (17) is satisfied. It is determined that countermeasures need to be taken (V7). As countermeasures satisfying the equation (17), the load connected to the distribution line is switched to another distribution line, or the distribution substation bank is moved to one side.

| ΘA ′ | ≧ θi (= | θx | + | θα |) (17)
In this way, the safety margin addition loop point phase difference θi of the loop point obtained by adding the safety margin | θα | is the loop allowable phase difference at the time of loop as viewed from the distribution line allowable currents IA and IB | θB '|, | θA It is determined whether or not it is within “|” using the above equations (16) and (17), and whether or not loop switching is possible is determined.

  FIG. 11 shows the safety margin addition loop point phase difference θi (= | θx | + | θα |), the loop allowable phase difference | θA ′ |, and the loop allowable phase difference | θB ′ according to the polarity of the loop point phase difference θx. It is explanatory drawing of the relationship with |. When the loop point phase difference θx is positive with respect to the reference phase difference θa of the distribution line 11a, the safety margin addition loop point phase difference θi (= | θx | + | θα |) is the loop allowable phase difference | If θB ′ | is less than or equal to the range, it is determined that loop switching at the loop point is possible. Similarly, when the loop point phase difference θx is negative with respect to the phase difference θa of the distribution line 11a, the safety margin addition loop point phase difference θi (= | θx | + | θα |) is the loop allowable level. If the phase difference is equal to or smaller than | θA ′ |, it is determined that loop switching at the loop point is possible.

  Next, the case where the power flow P applied to the 66 kV transmission system is taken into consideration and the loop point phase difference is calculated (comparative example), and the power flow P applied to the 66 kV transmission system as in the embodiment of the present invention is considered. The calculation result is compared with the case where the simple calculation is performed (excluded from the calculation).

<Comparative example>
FIG. 12 is a system diagram in a case where the loop point phase difference is calculated in consideration of the power flow P applied to the 66 kV transmission system in the comparative example of the present invention.

(1) Data acquisition processing (upper system information)
Upper system impedance:% Zg = 0.2326,% Zf = 0.5, 66 kV transmission line impedance:% Zh = 0.067,% Zi = 0.0914,% Ze = 0.0702,% Zd = 0.0548 % Zk = 0.1625. Power flow applied to 66 kV transmission line: Ph = 45 MW, Pi = 21 MW, Pe = 28 MW, Pd = 13 MW, Pk = 14 MW.

(Distribution system information)
Ij, Ic: J, C distribution substation bank current [A], and the obtained current value (Ij = 560 [A], Ic = 1210) is expressed by the equation (P = √3 · V · I · cos θ) To convert it to a power value. Power factor cos θ (= 0.95). Effective power of J distribution substation bank: Pj = √3 · V · Ij · cos θ = √3 × 6.6 kV × 560 [A] × 0.95 = 6 MW, effective power of C distribution substation bank: Pc = √3 · V · Ic · cos θ = √3 × 6.6 kV × 1210 [A] × 0.95 = 13 MW.

  a distribution line impedance:% Za = 8.744, b distribution line impedance:% Zb = 9.31, Ia, Ib are a, b distribution line currents, and obtained current values (Ia = 177 [A], Ib = 228 [A]) is converted into a power value by the equation (P = √3 · V · I · cos θ). Power factor cos θ (= 0.95). Effective power of a distribution line: Pa = √3 · V · Ia · cos θ = √3 × 6.6 kV × 177 [A] × 0.95 = 1.9 MW, b Effective power of distribution line: Pb = √3 · V · Ib · cos θ = √3 × 6.6 kV × 228 [A] × 0.95 = 2.5 MW.

(2) Loop target reference setting)
The upper system substation as a reference is set with the A substation as the reference. The reference distribution line is set with the a distribution line as the reference.

(3) Calculation of upper system phase difference θ0-Since the circuit breaker open position of the upper system substation is one and the phase of the acquired reference substation is the upper system phase difference, the upper system phase difference θ0 is θ0 = −1.00 [degree]. The higher system phase difference θ0 is expressed by the equation (A1).

θ0 = [{Pg ·% Zg− (Pf ·% Zf + Pk ·% Zk)} / 1000]
× (180 / π) = − 1.00 [degree] (A1)
[Calculation taking into account the power flow of 66 kV transmission lines]
In order to perform the calculation considering the power flow applied to the 66kV transmission line, the phase difference of the power flow applied to the 66kV transmission line connected from the A substation to the B substation is obtained at the reference substation (A substation). The phase difference {− (Pk ·% Zk / 1000) × (180 / π)} applied to the 66 kV transmission line between the A substation and the B substation is excluded from the phase difference θ0 (= −1.00 [degree]). become. As a result, as shown in the equation (A2), a phase difference θ0 ′ excluding the phase difference for the power flow applied to the 66 kV transmission line connected from the A substation to the B substation is obtained.

θ0 ′ = θ0 − {− (Pk ·% Zk / 1000) × (180 / π)}
= −1.00 + (Pk ·% Zk / 1000) × (180 / π)}
= −1.00 + (14 × 0.1625 / 1000) × (180 / π)
= −1.00 + 0.13 = −0.87 [degree] (A2)
(4) Loop point phase difference calculation of loop points First, the phase θa on the a distribution line side and the phase θb on the b distribution line side from the upper system substation (A substation, B substation) to the loop point X ( A3) and (A4) are used for the calculation.

θa = (Ph ·% Zh + Pi ·% Zi + Pj ·% Zj + Pa ·% Za) / 1000
= (45 × 0.067 + 21 × 0.0914 + 6 × 7.584
+ 1.9 × 8.744) / 1000 (A3)
θb = (Pe ·% Ze + Pd ·% Zd + Pc ·% Zc + Pb ·% Zb) / 1000
= (28 x 0.0702 + 13 x 0.0548 + 13 x 7.38
+ 2.5 × 9.31) / 1000 (A4)
The phase difference Δθ between the ab distribution lines from the upper system substation (A substation, B substation) to the loop point X is obtained from the equation (A5). Equation (A5) corresponds to Equation (4) described above.

Δθ = (θa−θb) (A5)
When the equations (A3) and (A4) are substituted into the equation (A5) and [rad] is converted into [degrees], the phase difference Δθ becomes Δθ (≈−3.14 “degrees”).

  Since the loop point phase difference θx of the entire loop is expressed by the above-described equation (7), when the equations (A2) and (A5) are substituted into the equation (7), the equation (A6) is obtained.

θx = θ0 ′ + Δθ = −0.87 + (− 3.14) = − 4.01 [degree] (A6)
(5) Calculation of loop impedance The loop impedance% ZL is obtained by the following equation (A7).

% ZL =% Za +% Zb +% Zc +% Zd +% Ze
+% Zf +% Zg +% Zh +% Zi +% Zj
= 8.744 + 9.31 + 7.38 + 0.0548 + 0.0702
+ 0.5 + 0.2326 + 0.067 + 0.0914 + 7.584
= 34.035 (A7)
(6) Allowable current calculation during loop as seen from distribution allowable current The loop allowable currents IA and IB of the a and b distribution lines are expressed by the above-described equations (9) and (10). When the a and b distribution line short-time allowable current Iu is 600 [A], the a distribution line load current Ia (= 177 [A]) and the b distribution line load current Ib (= 228 [A]) Substituting into the equations (9) and (10), the loop allowable currents IA and IB of the a and b distribution lines are expressed by the equations (A8) and (A9).

IA = Iu-Ia = 600-177 = 423 [A] (A8)
IB = Iu-Ib = 600-228 = 372 [A] (A9)
(7) Allowable phase difference calculation during loop from the viewpoint of allowable distribution current The allowable phase differences | θA ′ | and | θB ′ | of the loop point phase difference of the loop point X are expressed by the above-described equations (11) and (12). Indicated. Substituting the loop impedance obtained by the equation (A7), the loop allowable currents IA and IB of the a and b distribution lines obtained by the equation (A8) and (A9) into the above equations (11) and (12), The loop allowable phase differences | θA ′ | and | θB ′ | are expressed by equations (A10) and (A11).

| ΘA '| = IA ×% ZL / 1520
= 423 * 34.035 / 1520 = 9.47 (A10)
| ΘB '| = IB ×% ZL / 1520
= 372 × 34.035 / 1520 = 8.33 (A11)
(8) Calculation of safety tolerance addition loop point phase difference θi of the loop point added with safety margin | θα | The safety tolerance addition loop point phase difference θi of the loop point added with safety margin | θα | (15). For example, when the safety margin | θα | is 0.7, the safety tolerance addition loop point phase difference θi is expressed by the equation (A12).

θi = | θx | + | θα | = | −4.01 | + | 0.7 | = 4.71 (A12)
(9) Loop tolerance judgment based on the calculation result of safety margin addition loop point phase difference θi The safety margin addition loop point phase difference θi of the loop point added with safety margin | θα | is determined from the distribution line allowable currents IA and IB. Whether or not the phase difference is within the allowable phase differences | θA ′ | and | θB ′ | at the time of the loop is determined using the above-described equations (16) and (17).

  Since the loop point phase difference θx of the entire loop has a negative polarity (θx = −− 4.01 [degrees]) as shown by the equation (A6), the loop allowable phase difference of the above equation (17) | θA ′ | is applied. Since | θA ′ | = 9.47 from the formula (A10) and θi = 4.71 from the formula (A12), the above formula (17) is satisfied.

  FIG. 13 illustrates the loop allowable phase differences | θA ′ |, | θB ′ |, the safety margin addition loop point phase difference θi, and the loop point phase difference θx of the entire loop when the a distribution line in the comparative example is used as a reference. FIG. With reference to the a distribution line, the phase difference θb of the b distribution line with respect to the a distribution line is indicated by advance (+) and delay (−). As shown in the equation (A6), when the loop point phase difference θx of the entire loop is negative (θx == − 4.01 [degrees]), the loop allowable phase difference | θA ′ | (= 9.47 [degrees]) applies.

  Since the loop point phase difference θx of the entire loop has a negative polarity (θx = −− 4.01 [degrees]) as shown by the equation (A6), the loop allowable phase difference of the above equation (17) | θA ′ | is applied. Since | θA ′ | = 9.47 from the formula (A10) and θi = 4.71 from the formula (A12), the above formula (17) is satisfied.

<Example>
FIG. 14 is a system diagram in the case where the loop point phase difference is calculated without taking into consideration the power flow P applied to the 66 kV transmission system in the embodiment of the present invention. Since it is the same as the system diagram of the comparative example shown in FIG. 12 and (1) data fetching process and (2) reference setting of loop target) are the same, description thereof will be omitted.

(3) Calculation of upper system phase difference θ0 • Since there is one open circuit breaker in the upper system substation and the acquired phase is the upper system phase difference, the upper system phase difference θ0 is θ0 = −1. 00 degrees. The higher system phase difference θ0 is expressed by the equation (A1 ′).

θ0 = [{Pg ·% Zg− (Pf ·% Zf + Pk ·% Zk)} / 1000]
× (180 / π) = − 1.00 [degree] (A1 ′)
[Calculation of phase difference of power flow applied to 66kV transmission line is omitted]
Since the phase difference in this part is a minute value below the decimal point, it is a slight error even if omitted. Therefore, in the embodiment, the following phase differences are omitted.

Phase calculation for 66 kV transmission line between A substation and B substation (Pk ·% Zk / 1000) × (180 / π) ≈0.13 [degree]
Phase calculation for 66 kV transmission line between A substation and J substation {(Ph ·% Zh) + (Pj ·% Zj) / 1000} × (180 / π) ≈0.28 [degree]
Phase calculation for 66 kV transmission line between B substation and C substation {(Pe ·% Ze) + (Pd ·% Zd) / 1000} × (180 / π) ≈0.15 [degree]
(4) Loop point phase difference calculation of loop points First, the phase θa on the a distribution line side from the upper system substation (A substation, B substation) to the loop point X, and the phase θb on the b distribution line side are compared. Unlike the case of the example, it is obtained by the equations (A3 ′) and (A4 ′).

θa = (Pj ·% Zj + Pa ·% Za) / 1000
= (6 × 7.584 + 1.9 × 8.744) / 1000 (A3 ′)
θb = (Pc ·% Zc + Pb ·% Zb) / 1000
= (13 × 7.38 + 2.5 × 9.31) / 1000 (A4 ′)
The phase difference Δθ between the ab distribution lines from the upper system substation (A substation, B substation) to the loop point X is obtained from the equation (A5 ′). The expression (A5 ′) corresponds to the expression (4) described above.

Δθ = (θa−θb) (A5 ′)
When the equations (A3 ′) and (A4 ′) are substituted into the equation (A5 ′) and [rad] is converted into [degrees], the phase difference Δθ is different from the comparative example by Δθ (≈−3.27 “ Degree ").

  Since the loop point phase difference θx of the entire loop is expressed by the above-described equation (7), if the equations (A2 ′) and (A5 ′) are substituted into the equation (7), the comparison is made according to the equation (A6 ′). The loop point phase difference θx of the entire loop having a value different from the example is obtained.

θx = θ0 + Δθ = −1.00 + (− 3.27) = − 4.27 [degrees] (A6 ′)
(5) Calculation of Loop Impedance The loop impedance% ZL is the same as that in the comparative example, and the loop impedance% ZL having the same value as in the comparative example is obtained by the following formula (A7 ′).

% ZL =% Za +% Zb +% Zc +% Zd +% Ze
+% Zf +% Zg +% Zh +% Zi +% Zj
= 8.744 + 9.31 + 7.38 + 0.0548 + 0.0702
+ 0.5 + 0.2326 + 0.067 + 0.0914 + 7.584
= 34.035 (A7 ')
(6) Calculation of allowable current during loop from the viewpoint of distribution allowable current The loop allowable currents IA and IB of the a and b distribution lines are the same as in the comparative example, and are shown by the formulas (A8 ′) and (A9 ′). It is.

IA = Iu-Ia = 600-177 = 423 [A] (A8 ')
IB = Iu-Ib = 600-228 = 372 [A] (A9 ')
(7) Calculation of allowable phase difference in loop as viewed from distribution allowable current Allowable phase difference | θA '|, | θB' | of loop point phase difference of loop point X is the same as that in the comparative example, and (A10) This is expressed by the equation (A11).

| ΘA '| = IA ×% ZL / 1520
= 423 × 34.035 / 1520 = 9.47 (A10 ′)
| ΘB '| = IB ×% ZL / 1520
= 372 × 34.035 / 1520 = 8.33 (A11 ′)
(8) Calculation of safety tolerance addition loop point phase difference θi of the loop point added with safety margin | θα | The safety tolerance addition loop point phase difference θi of the loop point added with safety margin | θα | (15). For example, when the safety margin | θα | is 0.7, the safety tolerance addition loop point phase difference θi is expressed by the equation (A12 ′).

θi = | θx | + | θα | = | −4.27 | + | 0.7 | = 4.97 (A12 ′)
(9) Loop tolerance judgment based on the calculation result of safety margin addition loop point phase difference θi The safety margin addition loop point phase difference θi of the loop point added with safety margin | θα | is determined from the distribution line allowable currents IA and IB. Whether or not the phase difference is within the allowable phase differences | θA ′ | and | θB ′ | at the time of the loop is determined using the above-described equations (16) and (17).

  Since the loop point phase difference θx of the entire loop has a negative polarity (θx == − 4.27 [degrees]) as shown by the equation (A6 ′), the loop allowable phase difference of the above equation (17). | ΘA '| is applied. Since | θA ′ | = 9.47 from the expression (A10 ′) and θi = 4.97 from the expression (A12 ′), the above expression (17) is satisfied.

  Thus, even when the power flow P applied to the 66 kV transmission system is not taken into consideration as in the embodiment, the loop is applied in the same manner as when the power flow P applied to the 66 kV transmission system is taken into consideration. Switching can be determined accurately.

  According to the embodiment of the present invention, when switching a distribution system to a different system loop, it is possible to determine whether or not switching is possible without performing on-site measurement by a loop checker (phase angle measuring device), thereby reducing field work and improving efficiency. . In addition, when calculating the phase difference of the loop point, it is not necessary to collect the power flow P of the upper system and to calculate the power flow P related thereto. By omitting the power flow P applied to the 66 kV transmission system from the calculation, a simple and inexpensive calculation can be achieved.

  In addition, in the actual upper system, the majority of the systems have multiple points where the power substation breakers are always disconnected, so there are multiple phase differences depending on the system status. However, since the composite value of the phase difference of the host system is obtained by angle composition calculation, simple and inexpensive calculation can be achieved regardless of the state of the host system.

  In addition, the total phase difference is obtained by summing the phase difference of the upper system at the location where the power supply substation breaker is always turned off and the phase difference from the distribution substation bank to the distribution line loop point, and this is used to measure the past history. The safety margin is determined using the maximum and average values of the error between the calculated value and the calculated value, and the phase difference at the loop point obtained by adding the safety tolerance to the calculated phase difference is the distribution line allowable current. Therefore, it is possible to provide a safe and simple method for determining whether or not different system loops can be switched, for determining whether or not the current phase is within the range of the loop allowable phase difference at the time of the loop.

  The embodiment of the present invention has been presented as an example, and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

11 ... Distribution line, 12 ... Distribution substation bank, 13 ... Upper system substation, 14 ... Breaker

Claims (3)

When switching a loop by switching a switch at the loop point of two distribution lines with different substations in the upper system, calculate the loop point phase difference at the loop point of the two distribution lines and calculate the loop tolerance at the loop point. In the distribution line different system loop switching possibility determination method for calculating the phase difference and determining whether the loop switching is possible by comparing the loop point phase difference and the loop allowable phase difference.
The calculation of the loop point phase difference is performed by adding the upper system phase difference obtained by angle synthesis of the phase difference of the circuit breaker open part of the upper system substation and the distribution system phase difference of the loop points of the two distribution lines. A method for determining whether or not a distribution line different system loop can be switched.   A safety margin in consideration of a calculation error of the loop point phase difference is prepared in advance, and whether or not the loop can be switched is determined by adding a safety margin to the loop point phase difference. 2. A method for determining whether or not to allow switching between different distribution line loops according to claim 1, wherein a phase difference is obtained, and when the safety tolerance addition loop point phase difference is less than or equal to the loop allowable phase difference, the loop switching is determined to be possible. . The maximum value of the error between the calculated value of the loop point phase difference and the actual measurement value is set as the maximum error, and the average value of the error between the calculated value of the loop point phase difference and the actual measurement value is obtained in advance as the average error, The safety margin is determined as follows according to the polarity of the phase difference of the loop points, and the method for determining whether or not the distribution line different system loop switching is possible.
(1) When the polarity of the loop point phase difference is positive When the difference between the loop allowable phase difference of the non-reference distribution line that is not the reference phase of the two distribution lines and the loop point phase difference is smaller than the maximum error Uses the maximum error as the safety margin, and when it is larger than the maximum error, the average error as the safety margin.
(2) When the polarity of the loop point phase difference is negative When the difference between the loop allowable phase difference of the reference distribution line of the reference phase of the two distribution lines and the loop point phase difference is smaller than the maximum error The maximum error is set as the safety margin, and when the maximum error is larger than the maximum error, the average error is set as the safety margin.

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