JPH03215115A - Bus protecting relay device - Google Patents

Abstract

PURPOSE:To set an optimal suppression amount and prevent malfunction by determining the amount of suppression in accordance with the maximum value of the sum of currents and the value of the amount of operation. CONSTITUTION:The values of current at respective points are read into a computer 9 through a plurality of sample hold circuits 5 and a multiplexer 6. The absolute value of vector sum of currents of respective phases of bus bars are determined as the amount of operation Id while larger one between the sum Ip of only the positive waves of an instantaneous value and the sum IN of negative waves only is determined as the maximum value IMA of the sum of currents. The product of a dicision coefficient K1 (0<K1<1) by the maximum value IMA is determined as a condition deciding value IC while the product of a first operating coefficient KR1 (0.4<KR1<0.5) by the maximum value IMA is determined as a first amount of suppression IR1 and the product of a second operating coefficient KR2 (0.8<KR2<1) by the amount of operation Id is determined as a second amount of suppression IR2. The amount of suppression IRE becomes equal to IR1 in a period T1 wherein Id<Ic while the amount of suppression IRE becomes equal to the second amount of suppression IR2 in a period T2 wherein Id>Ic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a busbar protection relay device that is a protection device for annular busbars in a power system. [Prior Art] Figure 8 is a single-line wiring diagram in which a busbar protection relay device is provided to protect a ring busbar and a portion of the busbar. In this figure, circuit breakers 21, 22. 23. Each of the busbars divided by 24 constitutes an annular busbar 100 that is connected in a ring, and the busbar between the circuit breakers 2l and 22 is designated as the A busbar as shown in the figure, and this A busbar is protected. The bus protection relay for this purpose is called the A bus protection relay 4A. A
From the bus bar is terminal 32A. 33^ is connected, and instrument current transformers 12A are connected to these terminals 32A and 33A, respectively.
．． 13^, instrument current transformers 11A and 14A are installed near the circuit breakers 21 and 22, respectively, and these 4
Two instrument current transformers l1^l2^. Secondary currents of 13A and 14A are input to the A bus protection relay 4A. Ratio differential relays are generally used as busbar protection relays. Taking the A bus as an example, the instrument current transformer H I
Four 1t flows 1. measured by IA, 12A, 13^, 14^. Vector sum of (K=1.2.3.4)! - is taken as the operating amount, and a value proportional to the scalar sum Id is taken as the suppression amount, so that the operation is made when the ratio of the inflow current to the outflow current deviates from 1 to a certain extent. This can be expressed as a formula as follows. 1, -K. Ij Ishin1>K●
(1) Here, ■, ; Vector sum current of each terminal! , ;Each terminal current K. 4; Ratio coefficient Σ■Iris; Scalar sum current (-Is) of each terminal K. ;
Positive value close to 0 (theoretically 0 is fine) The reason for having this so-called ratio suppression characteristic is that when a fault occurs outside the bus bar, the fault current concentrates on one terminal and flows out. There is a significant difference in the liability between the instrument current transformers, and as a result, the error t current of the instrument current transformer at the outflow end increases, and the operating amount is no longer 0. Therefore, in order to avoid malfunction due to this, It is obtained by adding a suppression amount proportional to the magnitude of the inflowing current. Regarding the error points of instrument current transformers during external faults, it is desirable to have a ratio that is suppressed as much as possible to prevent malfunctions. Most of the recent relays are digital type, and the current value input from the current transformer is converted into a digital quantity and stored in the memory of the built-in computer, and if necessary, it is processed by cpυ. It is used to output the data to the outside of the computer using an output device as appropriate. Equation (1) above is also processed by the CPU. By the way, a problem peculiar to the case of annular busbars is that even in the event of an internal fault within the busbar, terminals from which current flows may sometimes occur. For example, in Fig. 8, if a ground fault occurs in the A bus, it will circulate from the instrument current transformer 11A through the annular bus, pass through the instrument current transformer 14^, and return to the A bus, causing a ground fault. This is a case where the flow is 1t. In such cases, if the suppression ratio is large, there is a risk that the suppression may be too strong depending on the value of the outflow current, and the ratio differential relay in the bus protection relay device may not operate even though it is an internal fault. therefore,
In such cases, it is desirable that the suppression ratio is not too large, which is a problem that conflicts with the above. In order to solve these problems, the
Some changes were made in Publication No. 88. An overview of this previously proposed technology is as follows. Figure 9 shows a certain mother I9101 and the three terminals 31 connected to it,
32. 33 is a main part single line diagram showing a case where a ground fault X occurs on the side opposite to the busbar of the instrument current transformer 13 provided at the terminal 33 in the busbar protection range 110 consisting of the busbar protection range 110 consisting of the terminal 33. In this figure, an instrument current transformer 11 provided at the terminal 3l
11, the current measured by the instrument current transformer l2 provided at the terminal 32 is designated as it, the current measured by the instrument current transformer l3 provided at the terminal 33 is designated as i, and this bus 1
Ground fault X at terminal 33, which is outside the protection range 110 of 01
Assume that this has occurred. FIG. 10 is a waveform diagram when the waveform of the current i, which is the secondary current of the instrument current transformer 13 in FIG. 9, is deformed due to saturation of the iron core. As mentioned above, instrument current transformers! 1, 12. The total vector sum of 13 secondary currents 1+, I, j3 is 14, and the current flowing into the bus 101 (1+Mo1.
) is the instantaneous value of ++s, and the instantaneous value of the outflow current (here simply i,) is ■. , and the larger of these IR3 and IR2S is the maximum current sum value 1 l. Let it be lA. Kc from 0 to 1
The product of Kc and IREA is the coefficient between
d, these waveforms will be as shown in Figure lO. The period T in the figure is a period in which the iron core of the instrument current transformer l3 is not saturated, and the inflow and outflow currents are equal, so the operating current ■4 is 0, so l. <IC is established, and this state is called the first state. During the period T8, the iron core of the instrument current transformer l3 is saturated, so that the operating current Id does not become 0 as shown in the figure, but Id>Ic, and this state is referred to as a second state. In the above-mentioned publication, by adopting the value obtained by adding the diagonal lined area downward to the left in Figure 10 (A) to the amount of suppression during period T1, it is possible to prevent malfunctions due to saturation of the core of the current transformer. I'm in the middle of the day. That is, the amount of suppression is the sum of the ICs in the downward-left diagonal line and the upward-left diagonal shaded area in FIG. 10(A). Figure 11 is a waveform diagram showing the waveform when the iron core of the instrument current transformer is saturated. In this figure, (a) shows the case when the iron core is on the verge of saturation and the current sum Id is still 0, and from (b) onwards, the saturation rate of the iron core increases as it goes down. The diagrams (a) to (f) on the left are the current I3, and the diagrams (6) to (1) on the right are the operating amount ■. When the waveforms on both sides are added, they match the primary current of the instrument current transformer 13. [Problem to be Solved by the Invention] As is clear from the comparison between FIG. 11 and FIG. The problem arises that suppression becomes difficult to apply. The first peak in Figure 11 (a) to (f) for the sum of the respective areas of the first peak with diagonal lines in Figure 11 (a) to (f) and the waveforms in Figure 11 (6) to (1) If we define the saturation rate by expressing the ratio of the area of the mountain as a percentage, the saturation rate is 60% using the above method.
The limit is around 70%. However, the increase in installed capacity,
The saturation rate is 80 due to demands for improved protection ability, etc. There is a need for a method that is effective to a certain extent, and the problem is that the above-mentioned methods cannot satisfy this requirement. This invention can be used in the event of an external accident that should normally result in inoperation.
The purpose of this invention is to provide a bus protection relay device that does not malfunction up to the aforementioned saturation rate of about 80%. [Means for Solving the Problems] In order to solve the above problems, according to the present invention, the secondary current of the instrument current transformer provided at each terminal of the bus bar is used as an input signal, and the vector of the current at each of these terminals is The absolute value of the sum is the motion amount l
．． Binding, operation amount l. In a busbar protection relay device consisting of a ratio differential protection relay, the suppression amount IRE for suppressing relay operation is calculated from each terminal current, and the sum Id of only the positive wave of the instantaneous value of each terminal current and the negative wave. sum of only 18
The larger value of the sum of currents is defined as the maximum current value ■■, and the product of the determination coefficient K1 whose value is within the range of more than O and less than 1 and the maximum value of the current sum IMA is defined as the state determination 4IREc, and the value is 0. 4
Is the first operation in the range greater than or equal to 0.5? Several km, and the maximum value of the current sum ■. The product is the first suppression amount! , 1, the second calculation coefficient Km whose value is within the range of 0.8 or more and less than 1
The product of the operation amount Id and the operation amount Id is set as the second suppression amount IR3, and the operation amount r. is smaller than the state determination (IIc) as the first state, and the suppression amount ■. in the period T. during which this first state is satisfied is the first suppression amount I
equal to RE, and the operation amount Id is the state determination value 1c.
is defined as a second state, and the suppression amount in period T2 in which this second state is satisfied is defined as the second state.
Furthermore, the input signal is the secondary current of the instrument current transformer provided at each terminal of the bus, and the absolute value of the vector sum of these terminal currents is the operating amount I.
d, and the motion amount l. In a busbar protection relay device consisting of a ratio differential protection relay, the suppression amount ■■ for suppressing relay operation is calculated from the above-mentioned terminal currents. The larger value of the sum of waves only I8 is the maximum value of the current sum■. Then, the sum IP of only positive waves and the sum of only negative waves of the instantaneous value of each terminal current? ．． The smaller value of t is the minimum value of current sum IM+, and the judgment coefficient K whose value is within the range of more than 0 and less than 1 and the maximum value of current sum ■HA
The product of the first calculation coefficient KR1 whose value is within the range of 0.4 or more and less than 0.5 and the maximum current sum value IMA is the first suppression amount 1■, The product of the second calculation coefficient KR1 whose value is within the range of 0.6 or more and less than 1 and the maximum current value +xa is determined as the second suppression amount (2). 2. The sum of the first suppression amount IRR and the motion I Im is the third suppression amount flu
and the amount of operation I. is the state judgment value ■. A first state is when the amount of suppression is smaller than l. The first suppression II
equal to RE and the amount of operation ! 4 is the state determination value Id
A second state is when the current sum is larger than 1, and half of the current sum maximum value IMA is the current sum minimum value IR during the period T.
The determination condition is whether the condition that a state equal to or smaller than 21 continues at a phase angle of 90° or more is satisfied, and from the time when the first state changes to the second state, from 180° in terms of electrical angle. During the period of 270°, the suppression amount IRE is set to the first value. equal to 51-1■, and the amount of suppression in that period T8! (2) shall be the third suppression amount IR3, and if the above-mentioned discrimination condition is satisfied, the third suppression amount IR3 at that point and a point in time a plurality of different predetermined phase angles before that point in time. Among the plurality of delay suppression amounts IR3 delayed from the delay suppression amount IR3, the maximum suppression amount is the suppression amount IRE in the period T, and the discrimination condition is set as the operation amount IRE in the period 1. It is assumed that the condition that the state where the current sum is equal to or smaller than the minimum current {MIN+ continues for 90' or more in terms of phase angle is satisfied. Also, the period T after satisfying the discrimination condition! Now let's assume that the relay device is inactive. [Function] In the configuration of the present invention, among the terminal currents as the secondary current of the instrument current transformer, the larger of the two current sums, the sum of the inflow current to the bus bar, and the sum of the outflow current IR3. The maximum value of the current sum as the value for both ■.

Find the determination coefficient K for values that are greater than O and less than 1.
, and the maximum current sum value Il4& to determine the state? r,
And the amount of movement ■. is this status judgment value ■.

The larger state is defined as the first state, and the smaller state is defined as the second state, and the product of the first calculation coefficient K1, which has a value within the range of 0.4 or more and less than 0.5, and the maximum current sum value IMA is calculated as the second state. The suppression amount in the first state described above is set to 1.1 and the suppression amount is 1.1.
The second calculation coefficient K! has a value within the range of more than 0 and less than 0.8. The product of the operation amount ■4 is the second suppression amount IR3! By setting the above-mentioned suppression in the second state as 1 1 at, in the case of an internal accident where a ground fault occurs within the range of busbar protection, the operating amount l4 will always be a larger value than the suppression amount ■■ and will be suppressed. The amount IRE will not be excessive and will be an appropriate value.
In the case of an external accident where a ground fault occurs outside the protection range, the current concentrates on one terminal where the ground fault occurred, and even if the core of the current transformer at that terminal becomes saturated, the core remains Operates due to loss of secondary current due to saturation 1 1
Even if m increases, this is determined to be the second state, and the above-mentioned second suppression amount ■■ is adopted as the suppression amount IR1 for the period T2 in which this state is satisfied, and as the degree of saturation increases. Increase the suppression amount ■16? This makes malfunctions less likely to occur.
First and second calculation coefficients K,,K. By setting the amount of suppression ■■ within the above-mentioned range and calculating the suppression amount ■■, normal operation can be performed when the degree of saturation is 80% or less. Note that a practical calculation method is to take the sum of only the positive waves of each secondary current as the inflow current (2), and the sum of only the negative waves of each secondary current as the outflow current (8). Further, the smaller value of the inflow t current Id and the outflow current I8 is set as the minimum current sum value IN+, the sum of the first suppression amount IRR and the operation amount Id is set as the third suppression amount 113, and the period T. Maximum current sum at ■. One-half of the current sum minimum value IR
The determination condition is whether or not the condition that the phase angle is equal to or smaller than 1 continues for 90'' or more is satisfied, and the suppression amount 1mt in the period T8 after satisfying this determination condition is the first suppression amount ■. , and the suppression amount IRE in the subsequent period T8 when the discrimination condition is not satisfied is set as the third
By setting the suppression amount to IR3, what if the instrument current transformers are saturated due to the influence of the low-pass filter through which the secondary current of each instrument current transformer of the bus protection relay device passes? It is possible to prevent the saturation rate from becoming 80% or less, which would lead to malfunction, and to reduce the inflow current (■) and the outflow current (1). Malfunctions can be avoided even when there is a phase difference between the two and the operating amount 1■ does not become zero even in steady state. Furthermore, when the above-mentioned discrimination condition is satisfied, the suppression amount IRE in the second state is changed to the third suppression amount at that point! +
13, and a plurality of delayed suppression amounts +111, which is the third suppression I1, which is delayed from a point in time by a multiple number of phase angles θ5 before that point. By setting the suppression amount to 1 1 RE at that point, it is possible to further increase the suppression amount, reliably preventing malfunctions, and also to prevent the operation delay period when it should operate from becoming too large. It can be done. In addition, as a determination condition, the condition that the operation amount 14 is equal to or smaller than 1.1 in the second state continues to be 90" or more in terms of phase angle is satisfied. Since the same effect as the above-mentioned discrimination condition can be obtained, the optimum discrimination condition can be adopted based on a comprehensive judgment that takes into account other factors.Furthermore, instead of increasing the suppression amount IRR, the period can be continued. A similar effect can be achieved by placing the electric device in an inoperable state. [Example] The present invention will be explained below based on an example. Figure 1 shows the data processing section of a digital bus protection relay. It is a block diagram showing the configuration. In this figure, a plurality of sample and hold circuits 5, a multiplexer 6, an A-[1 converter 7
n current input signals by! ．． ~■． is converted into a digital signal, input to the built-in computer 9, and stored in the storage section 92 via the data bus 94. The sample hold circuit 5, multiplexer 6 and A/D converter 7 are controlled by a control circuit 8. The operation amount and suppression amount in the above-mentioned conventional technology are calculated by the MPU 91 based on the current value data stored in the storage section 92, and an operation signal based on the result is outputted from the output section 93 to the outside of the computer 9. ．． The illustrations of the components that are naturally included in the relay, such as the amplifier and operating contacts, are omitted. Since this invention is also a technical content that is calculated using MPtl 91, the content will be explained below. FIG. 2 is a diagram showing changes in various quantities with respect to outflow t2it when a ground fault occurs within the bus bar protection range to explain the first embodiment of the present invention. In this diagram,
The horizontal axis is the sum of the outflow current 8, and the vertical axis is the sum of the absolute value of the inflow current.In Fig. 9, the ground fault occurred not at point 11, 12
．． 13 All illustrations are for the case where the iron core is not saturated. In this case, it is necessary to accurately detect ground faults with an appropriate amount of suppression. When the three currents +1, Ig, '3 have magnitude l and are all inflow currents, the outflow current is 0 and the inflow current is 3. This condition is expressed on the vertical axis, and when the current l, is the inflow current. is the outflow current 1 and the inflow 'gi current 2, and the straight line A represents the middle thereof. The amount of power I, which is the absolute value of the sum of three currents
1 is the sum of outflow current 1. but? When , it is 3, and the sum of outflow current is 1. When is 1, it becomes 1, and the middle is represented by straight line B. In order to create a bus protection relay device that can operate normally even when the saturation rate of the iron core of the instrument current transformer is around 80%, we will set the amount of suppression as follows. ■Determine the sum of inflow currents as the sum of only positive waves of the instantaneous values of the currents at each terminal.

■ Outflow as the sum of only the negative wave of the instantaneous value of each terminal current! ?
Find the sum of X and I8. The larger of ■Id and ■8 is the maximum current sum value IH&. ■Let K be the determination coefficient for values in the range of more than 0 and less than 1, and let K times the maximum current sum value IMA be the state determination {direct IP. ■Maximum current sum value■. The first calculation coefficient KR11 times the first
Let the suppression amount IRE be. ■K1 the second calculation coefficient for values in the range of more than 0.8 and less than 1! Then, K,t times the operation amount Id is the second suppression amount ■
Set it to 1. ■The operation amount Id is the state judgment value! . A smaller state? 1 state, and the period during which this state continues is defined as a period T1, and the amount of suppression during this period T1 is I II! The second suppression amount is adopted for . ■The state when the operation amount Id is larger than the state determination value Id is the second state, and the period during which this state continues is the period T! Binding,
The second suppression I.I. is added to the suppression amount IR1 during this period T8. ．． Adopt. ■ Integrate the motion amount ■4 determined in the previous section for a period that is an integral multiple of one cycle to find the motion amount integral M Ias. [Phase] Integrate the suppression amount 1.7 obtained in the previous section over a period that is an integral multiple of one cycle to obtain the suppression amount integral value ■■. ■I as
Activate the relay when Tas > Ke. (K
O! -i>0) The second calculation coefficient K ItO value is determined from the condition that if there is a 50% outflow current due to an internal fault, this is called a 50% outflow and the relay operates reliably in this case. That is, K +u-0. 5, the limit is reached at 50% leakage, and considering the hardware error ±2.5%, KR
The value of 2 can be found as follows. Id (1 Sat 0.
025) Kmt.I. +. (1±0.025)>0
・- (2)? , due to an internal accident that resulted in a 50% leak! ．． Since IHA = 2, substituting this into equation (2) to find KR2 yields the following. Kit< ((1±0.025)/(1±0.02
5)/2). i. =0.975/2.05=0.
476 Therefore, considering the margin, K m+ < 0.4
A value of about 5 is considered to be a reasonable value. However, as shown below, the larger the value of KR1, the more effective it is in suppressing the core saturation of the instrument current transformer in the event of an external fault. The requirement for the saturation rate of the iron core of current instrument current transformers is approximately 80%, and in order to satisfy this value, KR1 is required at K = 0.45.
≧0.875, and KR1≧0.9 for KR1-0.4. Note that the judgment coefficient KC is a coefficient used to distinguish between the saturated period and the non-saturation period of the core of the instrument current transformer in the event of an external accident, and the judgment coefficient K, with a typical waveform, is within the range of 0 and 1. However, in general, a bond in the range of 0.3 to 0.9 is appropriate. The three coefficients are Kc -0.9, Km, 10. 9, Ka. = 0.45, and the respective quantities are shown in Figure 2. Is the boundary between period T and period T1 an operation? r a and the state judgment amount ■. This will be the location of the intersection with . FIG. 2 is an example assuming a ground fault within the busbar protection range, but generally the suppression amount IIF adopted based on the above-mentioned method is always the operating amount ■. It is known that the appropriate value is smaller than . Figure 3 is a diagram showing the change in saturation rate when a ground fault occurs outside the bus bar protection range. In this article, the horizontal axis is the saturation rate, and the vertical axis is the sum of inflow currents r, and as in Figure 2, only the ratio matters, so the maximum value is set to 1. When the saturation rate is 0%, the sum of outflow currents is 1. is the same as the sum of inflow currents ■, so the operating current l, which is also the difference between them, is 0. When the saturation rate is 100%, the outflow current IN becomes 0, so the operating current 1d matches the sum of inflow currents IP, and the operating current 1d at a saturation rate between these two. The graph is shown by the dashed-dotted line. In this figure, the two straight lines, the solid line and the dashed line downward to the left, are the suppression ii
IRE, and the second calculation coefficient K Ig =0.
45, the chain line is KR1-0.9, and the solid line is Kml =
This is the case of 0.8. Operating current ■ 4 Dot-dash line straight line? Controlled IR3! The intersection with the straight line becomes the permissible saturation rate, but as shown in the figure, the dashed line of KR1-0.9 is about 8
The saturation rate is 2%, and K. ．． The solid line with = 0.8 has a saturation rate of approximately 70%. Therefore, in order to prevent malfunctions up to a saturation rate of 80%, Kmz=0.4
5, KR1=0.9 is a reasonable value. Incidentally, in the case of KR1-0.95, although not shown, the permissible saturation rate is approximately 90%. Incidentally, in FIG. 1, a low-pass filter (generally referred to as a low-pass filter) (not shown) is inserted in front of the sample hold circuit 5. Its purpose is a current signal! The purpose is to remove or reduce the high frequency components contained in 1 to ■, and specifically, ■prevent the intrusion of external noise, ■reduce the effects of harmonic distortion of the grid current, and ■based on the sampling theorem. This is to remove aliasing errors, etc. all at once. The circuit into which this low-pass filter is inserted is an analog circuit, so the low-pass filter is also an analog filter. Even if conditions are set such that malfunction does not occur until the saturation rate of the instrument current transformer reaches 80%, as described above, the amount of suppression actually decreases due to the insertion of a low-pass filter, and as a result, the amount of suppression will decrease when the saturation rate is below 80%. A phenomenon occurs in which a malfunction occurs. There are many systems to which the method of the above embodiment can be applied, depending on the usage conditions such as system configuration, capacity, and capacity of the main instrument current transformer, but for systems that can be used even under harsher system conditions, Furthermore, it is necessary to adopt an improved method that is less prone to malfunctions. Figure 4 is a waveform diagram of the operating current ■4 showing a comparison between the case where a low-pass filter is inserted and the case where it is not inserted. In this figure, the operating current calculated from the current manually input to the computer 9 when no low-pass filter is inserted is assumed to be 141, and its waveform is indicated by a dotted line.
The waveform of the operating current ■, when a low-pass filter is inserted, is shown by a dotted line. Since a low-pass filter is a type of integrator, the output signal is a waveform signal that is delayed in time with respect to the input signal. Therefore, multiple 1i current signals 1
Absolute value of vector sum of r(j・1,2,...n)? Since the operating current (4) also has a low-pass filter, it has a waveform that is delayed in time as shown in this figure, compared to when there is no low-pass filter. As a result, (a) the point in time when the state determination value IP and Id match; 1. is at a later position than time t1 when there is no low-pass filter, so period T1, which is the period during which the first condition continues, becomes longer, and period T1, which is the period during which the second condition continues. As T8 becomes shorter, (b) the amount of operation l4 decreases. Since the suppression amount IRE is smaller in period T1 than in period Tt, the suppression amount ■■ is attenuated as a result, and there is also a synergistic effect with the decrease in the operation amount ■4 of Φ), making malfunctions more likely. occurs. In order to improve this problem, the amount of suppression is determined by the following method as a second embodiment of the present invention. However, it is necessary to satisfy the condition that malfunction does not occur even if there is a leakage current in the event of an internal fault. Since the sum of this outflow current does not exceed 50% of the sum of inflow currents, this can be achieved by preventing malfunction even when the sum of outflow currents is 50% of the sum of inflow currents. Now, in the second state where the operation amount Id is larger than the state determination value Ic, simply increasing the suppression amount may result in erroneous non-operation. For this reason, it is not only possible to simply determine the state at that time, but also to determine the time lapse of saturation of the instrument current transformer and the state before and after the saturation of the instrument current transformer Note 1) Instrument current transformer Note 2) Co: less than 50% Constant value Note 3) First state (!tlI interval T.) Note 4) Second state! I (Period Tg) The distinction between the first state and the second state is as shown in the table above, depending on the presence or absence of saturation of the instrument current transformer of the type of accident. Figure 5 is a waveform diagram showing the inflow current Id and outflow current ■8 over several cycles when an external fault occurs and the instrument current transformer is saturated. In this figure, the origin of the time axis is the point at which the external accident occurred. During the first period T1, since the instrument current transformer is not saturated, the inflow current Id and the outflow current! ,
The algebraic sum (called the hectoral sum) of is zero. During period T8, the instrument current transformer in the system where the external fault occurred was saturated and the current flowed out! . is not measured and becomes zero, and the operating current I
d becomes equal to the inflow current 1, resulting in a second state, and this period becomes period T2. As is clear from the figure, these periods T. and period T, are repeated alternately. At this time, there is a period T, which is a non-saturation period, once in a cycle, and the period has a phase angle of 90° or more. The reason for this is that the specifications for the main instrument current transformer in the bus protection device ensure that it does not saturate within a phase angle of 90°. Therefore, the saturation period, ie period T, is never longer than the phase angle of 270°. therefore,? The phase angle T, is 90
After continuing for ゜, when transitioning to period T2, it can be determined that this period T8 occurred due to an external accident, and the first suppression amount as in the above-mentioned example is set as the suppression amount summer ■ during that period. By adopting ■■, the operation amount ■4 is always smaller than the suppression amount IR3, so that it is always inactive and the possibility of malfunction can be eliminated. The response situation in the event of an internal accident using this method is as follows. In the case of an internal fault in which the outflow current I8 is small (below a certain value 00), the first state in the no-fault state changes to the second state, and the second state is maintained thereafter while the fault continues. Therefore, at the same time as an internal accident occurs, the suppression l1■ increases once and becomes inactive, but since the period during which the suppression Wkl-i increases is at most 270@, it becomes operational after that. Furthermore, in the case of an internal accident in which the outflow current exceeds C0 (however, below 50%), the operating amount Id increases while remaining in the first state, and the suppression amount 11 does not increase either, so the operating state is instantaneously achieved.

Does this mean that the inflow current Id and the outflow current ftIN are in phase? However, some systems consist of multiple power supply systems, and their phases may differ. In this case, the amount of suppression ■■ is the scalar sum of the currents at each terminal, so even in a steady state an unbalanced state occurs in which the sum of the absolute values of the inflow current and the sum of the absolute values of the outflow current are not equal. Even though there were no accidents, the operating current ■4 was not zero. This unbalance is considered to be a maximum of 50% leakage, and anything beyond this is an internal accident, so it is necessary to prevent the relay from operating even in the absence of an accident. FIG. 6 is a waveform diagram showing the waveforms related to the current sum after the occurrence of an external accident, where (a) in the upper row shows the waveform of the maximum current sum IMA and a half of it, and (b) in the lower row. ) is the inflow current ■,
The waveform of the minimum current sum IH+, which is the smaller of the absolute values of the outflow current IR3 and the outflow current IR3, is shown. Add the following logic to state determination so that the relay does not operate in the case of no accident as described above. That is, in the first state, the current sum is a large value ■. 1/2 is equal to or smaller than the minimum current sum + 111 for a phase angle of 90°. If the determination condition is satisfied, the third suppression amount I. , is adopted. This third suppression amount 1
13 is the value obtained by adding the operation amount Id to the first suppression amount r■. When such logic is added, as shown in Figure 6,
Even if saturation occurs in the instrument current transformer due to an external accident, this does not interfere with the condition that the amount of suppression increases as the first state changes to the second state. On the other hand, when an internal accident occurs, if the outflow current [H is less than 50%, the discrimination condition is not satisfied, so it is possible to distinguish between an internal accident and a no-fault condition (steady state). The calculation procedure for this second embodiment is as follows. ■Add the current of each terminal and calculate the absolute value to calculate the amount of operation! Find 4. ■ Find the current groups of the same polarity at the terminals and add the absolute values of these to determine the inflow current Id and outflow current ■.

Find. What are the values of these two? As mentioned above, the purpose is to find the larger one and the smaller one, so there is no problem even if the two are interchanged. ■Inflow current IF and outflow current 1. The larger one is set as the maximum current sum value IMA, and the smaller one is set as the single current sum maximum value rNl. ■Maximum current sum value! Find the product of ■ and the determination coefficient Kc and use this as the state determination value ■. ■Amount of movement■. and the state judgment value IP, and the operation amount ■,
When is small, the first state is used; otherwise, the second state is used. ■In the first state, 1/2 of the 1l flow maximum IMA
is smaller than or equal to the maximum current sum + 111, it is determined that there is no accident. ■The judgment result is whether or not the condition determined to be an accident-free state lasts at least 90 degrees in phase angle. It is determined that it is an accident, and the value obtained by adding the operation amount Id to the first suppression amount is set as the third suppression amount IR3, and the suppression amount ■■ is suppressed during this period? Set it to IR3. FIG. 7 is a waveform diagram for explaining the third embodiment of the present invention. The waveform shown by the dashed line in this figure is the waveform of the suppression amount calculated by the second embodiment, and this suppression amount is
Let it be IL. The waveform shown by the two-dot chain line shows the suppression amount rat when the phase angle is set to a delay angle θ within the range of 30° to 90°.
This is the waveform of delay suppression 1 1 +u+ shifted backward. The maximum current sum value of 111A indicated by the dotted line is shown as a reference for comparison. In this figure, when the above-mentioned discrimination condition is satisfied, the suppression amount ■■ at that time and the delay suppression amount IR3 are compared and the larger one is adopted as the suppression amount ■I. By doing this, the amount of suppression increases, making it possible to more reliably prevent malfunctions and minimizing the operation delay period in the event of an internal accident. In addition, in this example, the amount of suppression! ■The amount of delay suppression compared to ■ was limited to IREl+, but
A plurality of delay suppression amounts I corresponding to a plurality of different delay angles θI
Using RE, calculate the maximum value from the suppression amount +1t and these multiple delay suppression amounts IRE? By taking the amount of suppression at that point in time, it becomes possible to set a more appropriate amount of suppression and operation delay period in the event of an internal accident. The third suppression amount ■ is the suppression amount IRE in the second state when the discrimination condition is satisfied. Instead of increasing the suppression amount ■■ by a method such as determining the delay suppression amount ■■, the relay device is put in an inoperable state jl! You can also achieve the same purpose by locking it. Of course, even in this case, if the suppression amount +1E is set equal to a specific value as described above, it is practical because it allows common processing other than the difference in whether or not to put it in the inactive state. ．．
1/2 of the maximum current sum value IXA under the above-mentioned discrimination conditions
Instead of comparing the current sum minimum value IH+, the operation amount l
The same result can be obtained by comparing , and the minimum current sum value ■■. Which one to adopt is determined based on a comprehensive judgment that also takes into account other factors when creating the overall algorithm. [Effect of the invention] As mentioned above, this invention is a secondary current transformer for measuring instruments. Among the terminal currents as currents, the maximum value of the current sum (■) is the larger of the two current sums: the sum It of the inflow current to the bus bar, and the sum I of the outflow current A. Find the determination coefficient K for values in the range of more than 0 and less than 1, and the maximum current sum (1+xa
Let the product be the state judgment {lI[c, and the amount of movement ■. is this condition judgment value! , the larger state is the first state, the smaller state is the second state, and the first calculation coefficient K, which has a value within the range of 0.4 or more and less than 0.5, and the maximum t flow sum value IMA. Let the product be the first suppression amount ■■ and the suppression amount I1 in the first state described above, and the product of the second operation coefficient K, which has a value within the range of more than 0 and less than 0.8, and the operation amount Id. Second suppression 1
1 as the suppression amount IRE in the second state described above.
Therefore, in the case of an internal accident in which a ground fault occurs within the range of busbar protection, the operating amount Id is always equal to the suppression amount I. Suppress Dong ■. is an appropriate value without becoming excessive, and in the case of an external accident where a ground fault occurs outside the protection range,
Even if the current concentrates on one terminal where a ground fault occurred and the core of the current transformer at that terminal becomes saturated, what happens? Even if the operating position (1) increases due to the deficit in the secondary current due to saturation of the heart, this is determined to be the second state, and the period during which this state is satisfied is T! The above-mentioned second suppression amount is added to the suppression amount IR3! . By adopting this method and increasing the amount of suppression as the degree of saturation increases, malfunctions become less likely to occur. The first and second calculation coefficients K,,K. Set the above range to suppress the amount! By calculating ■, the saturation level is 80%.
The following operations can be performed normally. Note that the sum of only the positive waves of each secondary current is used as the inflow current Id, and the outflow current 1. A practical calculation method is to take the sum of only the negative waves of each secondary current. Also, the inflow current is 1, and the outflow current is 1! The smaller value of , and is the minimum current sum value ■d, and the first suppression amount! ■ and operation amount I
The sum with N is set as the third suppression amount IR3, and the current sum maximum value ■ during the period T1 in which the first state is satisfied. One-half of the current sum minimum value Idl. The determination condition is whether or not the condition that the phase angle continues to be equal to or smaller than 90° is satisfied, and the period T! after this determination condition is satisfied is satisfied. What? By setting the suppression amount IRE equal to the first suppression amount IR1 and setting the suppression amount IRE in the subsequent period T8 when the discrimination condition is not satisfied to the third suppression amount r+ts, each meter of the bus protection relay device It is possible to improve the saturation rate of 80% or less, which can lead to malfunction when the instrument current transformer is saturated due to the influence of the low-pass filter through which the secondary current of the instrument current transformer passes, and to reduce the inflow current [, And outflow current! , and the operating amount Id does not become zero even in steady state, malfunction can be avoided. Furthermore, when the above-mentioned discrimination condition is satisfied, the suppression amount IRE in the second state is changed to the third suppression 1 at that point.
Suppression amount IR3 corresponding to 1 ++3 and from that point? ! Different number of phase angles θ. The suppression amount is further increased by setting the maximum suppression amount among the plurality of delayed suppression amounts IRE, which is the third suppression amount 113 delayed from the previous point in time, as the suppression IIRE at that point in time. This makes it possible to reliably prevent malfunctions, and also to prevent the delay period for the operation from becoming too large. In addition, as a determination condition, the amount of movement in period T1! ．． The same effect as the above-mentioned discrimination condition can be obtained by determining whether the condition that the current sum is equal to or smaller than the minimum current sum value 1111 continues for a phase angle of 90 degrees or more, so other factors can be comprehensively considered. It is only necessary to make a judgment and adopt the optimal discriminant condition. Furthermore, instead of increasing the suppression amount tut, the same effect can be achieved by making the relay device inoperable during that period.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the data processing section of the bus protection relay device, and FIG. 2 is a waveform diagram of the operating current showing the influence of the low-pass filter in the second embodiment. , FIG. 5 is a waveform diagram showing an example of waveforms of an inflow current and an outflow current at the time of an external fault, FIG. 6 is a waveform chart showing a waveform at the time of an external fault, and FIG. A waveform diagram for explaining the embodiment, Fig. 8 is a single line connection diagram between the annular bus bar and the bus protection relay device, and Fig. 9 is a main single line diagram showing the case where a ground fault occurs outside the range of bus protection. Wiring diagram, No. 10
Figure 111 is a waveform diagram showing the current waveform when the core of the voltage transformer in Figure 9 is saturated, and Figure 111 is a waveform diagram showing the current waveform when the core of the voltage transformer is saturated. l4^...Instrument change 11, 12. 13. 14. 11^,
12A, 13A, flow device, 5... sample hold circuit, 6... multiplexer, 7...^-D converter, 8... control circuit, 9... combinator, 9l.
...MPU92...Storage section, 93...Output section, 94
...Data path, 21, 22. 23. 24...
- Breaker, 31, 32. 33, 34, 32A,
33A...Terminal, 100...Annular bus bar, lot.
... Bus line, ¥ 1 figure 2 mouth female young catch (%) figure 3 drawing 5 figure pigeon 6 figure δ bracket 10 figure seki → Shikaku → kudzu f / figure

Claims (1)

[Claims] 1) The secondary current of the instrument current transformer provided at each terminal of the bus bar is used as an input signal, the absolute value of the vector sum of these terminal currents is taken as the operating amount I_d, and the operating amount I_d is In contrast, in a busbar protection relay device consisting of a ratio differential protection relay, in which the suppression amount I_R_E for suppressing the relay operation is calculated from each terminal current, the sum I_P of only the positive wave of the instantaneous value of each terminal current and only the negative wave The larger value of the sum I_N is set as the maximum current sum value I_M_A, and the judgment coefficient K_1 whose value is within the range of more than 0 and less than 1
The product of the current sum maximum value I_M_A is the state determination value I_
c, and the first value is within the range of 0.4 or more and less than 0.5.
The product of the calculation coefficient K_R_1 and the maximum current sum value I_M_A is the first suppression amount I_R_1, and the product of the second calculation coefficient K_R_2 whose value is within the range of 0.8 or more and less than 1 and the operation amount I_d is As the second suppression amount I_R_2, the first state is when the operation amount I_d is smaller than the state determination value I_c, and the suppression amount I_R_E in the period T_1 in which this first state is satisfied is the first state. Suppression amount I
_R_1, and when the operation amount I_d is larger than the state determination value I_c, it is defined as a second state.
Suppression amount I_ in period T_2 when the condition is satisfied
A bus protection relay device characterized in that R_E is made equal to the second suppression amount I_R_2. 2) Use the secondary current of the instrument current transformer provided at each terminal of the bus as an input signal, set the absolute value of the vector sum of these terminal currents as the operating amount I_d, and suppress the relay operation with respect to the operating amount I_d. In a busbar protection relay device consisting of a ratio differential protection relay, in which the suppression amount I_R_E is calculated from each terminal current, the sum I_P of only positive waves and the sum I_N of only negative waves of the instantaneous values of each terminal current are large. This value is the maximum current sum value I_M_A, and the smaller value of the sum I_P of only positive waves and the sum I_N of only negative waves of the instantaneous values of each terminal current is the minimum current sum value I_M_
1, and the determination coefficient K whose value is within the range of more than 0 and less than 1
The product of _1 and the maximum current sum value I_M_A is defined as the state determination value I_c, and the first calculation coefficient K_R_1 whose value is within the range of 0.4 or more and less than 0.5 and the current sum maximum value I_M_
The product with A is the first suppression amount I_R_1, and the value is 0.6 or more 1
The product of the second calculation coefficient K_R_2 and the current maximum value I_M_A, which is within a range of less than , is the second suppression amount I_R_2,
The sum of the first suppression amount I_R_1 and the operation amount I_d is defined as a third suppression amount I_R_3, and the time when the operation amount I_d is smaller than the state determination value I_c is defined as a first state, and this first state is satisfied. Suppression amount I during period T_1
_R_E is set equal to the first suppression amount I_R_1, the operation amount I_d is larger than the state determination value I_c, the second state is set, and in period T_1, one half of the maximum current sum value I_M_A is the current The determination condition is whether the condition that a state equal to or smaller than the minimum sum value I_M_1 continues for 90 degrees or more in terms of phase angle is satisfied, and from the time when the first state changes to the second state, the electrical angle is Between 180° and 270°, the suppression amount I_R_E is made equal to the first suppression amount I_R_1, and the period T_2
A busbar protection relay device characterized in that a suppression amount I_R_E in is set as a third suppression amount I_R_3. 3) In the busbar protection relay device according to claim 2, when the discrimination condition is satisfied, the third suppression amount I at that time
_R_3 and a plurality of delay suppression amounts I_R_R delayed from a point in time by a plurality of different predetermined phase angles before that point in time.
, the maximum amount of suppression is the amount of suppression I in period T_2
A busbar protection relay device characterized by _R_E. 4) In the bus bar protection relay device according to claim 2 or 3, the determination condition is that the operating amount I_d is equal to or smaller than the minimum current sum value I_M_1 in period 1 at a phase angle of 90.
A busbar protection relay device characterized in that it determines whether or not a condition of continuing for more than ° is satisfied. 5) The busbar protection relay device according to one of claims 2 to 4, wherein the busbar protection relay device is characterized in that the relay device is brought into an inoperable state during a period T_2 after the determination condition is satisfied. .