JP2003324842A - Step-out protective relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein for step-out protection of a conventional power transmission line protector, either a voltage information on an opposite end of a power transmission line or that on both sides, high-voltage side and low-voltage side, of a transformer is required, and a communication facility or a measuring apparatus is required, resulting in high cost. <P>SOLUTION: A step-out protective relay is used for a protection relay of a power transmission line 6 connecting between an own end and an opposite end. A power transmission line impedance Z<SB>1</SB>from the own end to the opposite end, a voltage of the own end E<SB>α</SB>, and a current I<SB>α</SB>of the own end are used to calculate a voltage E<SB>β</SB>of the opposite end. Based on the voltage of the own end and that of the opposite end which is acquired by calculation, it is decided as being a step-out. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-out protection relay which is a protection device for a power system or a transformer.

[0002]

2. Description of the Related Art First, step-out protection in a transmission line protection device will be described. 4 and 6 are, for example, the Institute of Electrical Engineers of Japan, Technical Report No. 801, "Technology for relaying out-of-system / accident spread prevention"
P. FIG. 83 is a system configuration diagram described in FIG. 83 and a principle explanatory diagram for detecting out-of-step with this system configuration.

In FIG. 4, 3 is a bus of the substation α, and 1 is a bus.
The equivalent power supply behind this bus bar 3
Between impedance Z_α(Dots represent complex numbers, below
The same) of the equivalent power transmission line 5 is connected. 6 is transmission line a
Npedance Z_lIs a transmission line with a
3 to the bus 4 of the adjacent β substation. 2 is
The equivalent power supply behind the bus bar 4 is the equivalent power supply 2 and the bus bar 4.
Between impedance Z _βConnected by the equivalent transmission line 7
It

The transmission line 6 has a current transformer (C
T_α) 8 and breaker (CB_α) 12 are installed,
Similarly, a current transformer (CT_β) 9 and breaker (CB
_β) 13 is installed. For measuring bus voltage at both substations
And the transformer for the instrument (PT _α) 10 and voltage transformer
Bowl (PT_β) 11 is installed. 14 and 15 are power transmission lines
6 is a power transmission line protection device, 14 is an α substation, and 15
Is installed at the β substation. Transmission line protection devices 14 and 1
Between 5 is using communication system 16 and 17 respectively.
The measured current / voltage information is transmitted to the other party.
There is. In addition, E_αIs the voltage of bus 3, E_βIs the bus line 4
Pressure, I_αIs the transmission line current of the α substation, I_βIs the transmission of β substation
It is the electric wire current.

Next, the power transmission line protection devices 14 and 15 will be described with reference to FIG. Since the transmission line protection devices 14 and 15 have the same function, the transmission line protection device 14 of the substation α will be described. In FIG. 5, reference numerals 40 and 41 denote a partner end current receiving function and a partner end voltage receiving function, respectively, which obtain the current and voltage of the partner end using the communication systems 16 and 17 shown in FIG. Reference numerals 44 and 45 are a self-end current measuring function and a self-end voltage measuring function for measuring the current value and the voltage in the substation at the self-end by using CT _α 8 and PT _α 10, respectively.

Reference numerals 42 and 43 designate a self-end current measuring function 44 and a self-end current measured by the self-end voltage measuring function 45, and a self-end current transmitting function for transmitting the self-end voltage to the companion end by the communication systems 16 and 17, and It is a self-end voltage transmission function. Reference numeral 46 is a current differential protection function, which is the main function of power transmission line protection, and is a function that determines the differential value of the current value at the self-end and the current value at the other end, and determines whether or not there is an accident on the power transmission line 6. is there. If it is determined to be an accident, a command is output to cut off the CB _α 12 at the self-end. Since the details of the current differential protection function are not the gist of the present invention, description thereof will be omitted. Reference numeral 47 denotes a step-out determination function, and this function determines whether or not the step-out state is out of sync with the phase of the self-end voltage measured by the self-end voltage measuring function 45 and the phase end voltage obtained from the partner end voltage receiving function 41. To judge.

This step-out determination function will be described with reference to FIG. The case of the substation α will be described as a representative. The horizontal axis of FIG. 6 has the same phase as the self-end voltage E _α . Let us suppose that the second quadrant of this plane is called Φ _α and the third quadrant is called Φ _β . On this plane, the voltage E _β at the other end moves from Φ _α to Φ _β ,
When it moves from Φ _β to Φ _α , it is judged as out-of-step. The validity of this method is described in the Technical Report of the Institute of Electrical Engineers of Japan, No. 801, "Disruption of system / accident ripple prevention relay technology" p. 83.

The above is the conventional step-out protection in the transmission line protection device. Next, the step-out protection function in the conventional transformer protection device will be described with reference to FIGS. 7 and 8. In FIG. 7, 52 is a high-voltage side busbar of the substation, 50 is an equivalent power source behind the high-voltage side busbar 52, and the high-voltage side busbar 52 and the equivalent power source 5
The zero is connected by an equivalent transmission line 48 having an impedance Z _H. A transformer (TR) 60 having an impedance Z _T is connected from the high voltage side bus bar 52 to the low voltage side bus bar 53. Reference numeral 51 is an equivalent power supply behind the low voltage side bus 53, and the low voltage side bus 53 and the equivalent power supply 51 are connected by an equivalent power transmission line 49 having an impedance Z _L.

[0009] transformer (TR) 60 current transformer on the side of the high pressure side bus 52 (CT _H) 54 and breaker (CB _H) 58 are installed, as well as on the side of the low pressure side busbar 53 current transformer (CT _L) 55 and breaker (CB _L) 59 is installed. In addition, for the bus voltage measurement, the transformer for the high voltage side instrument (PT
_H ) 56 and a low voltage side instrument transformer (PT _L ) 57 are installed. 61 _{CT H 54, PT H 56,} CT L 55,
Measurement of PT _L 57 is added, a protector of the transformer 60. Note that E _H is the voltage of the high-voltage side bus bar 52, I _H
Is the high voltage side current of the transformer, E _L is the voltage of the low voltage side bus 53,
I _L is the low side current of the transformer.

Next, the function of the transformer protection device 61 will be described with reference to FIG. Reference numerals 70 and 71 denote a high-voltage side current measurement function for measuring high-voltage side and low-voltage side current values I _H and _IL using CT _H 54 and CT _L 55, respectively, and a low-voltage side current measurement function 72,
73 are bus voltage values E _H and E on the high voltage side and the low voltage side, respectively.
_L, and the high side voltage measurement function to measure using the PT _H 56 and PT _L 57, a low side voltage measurement function. 74 is a current differential protection function which is the main function of transformer protection, and takes the differential value of the high-voltage side current value I _H and the low-voltage side current value I _L etc. to determine whether or not the transformer 60 has an accident. Is a function for determining.

If it is judged as an accident, the circuit breaker CB _H 5
8. Output a command to shut off CB _L 59. Further, reference numeral 75 is a voltage drop determination function that realizes transformer accident detection as a fail-safe function, and the circuit breaker CB is obtained by ANDing the voltage drop determination signal and the accident determination signal determined by the transformer protection function 74. Cut off _H 58 and CB _L 59. Since the details of the differential protection function of the transformer 74 are not the gist of the present invention, description thereof will be omitted.

Reference numeral 76 denotes a step-out determination function. This function is similar to the step-out determination function of the conventional power transmission line protection device and is indicated by E in FIG.
Replace _α and E _β with the high voltage side voltage E _H and the low voltage side voltage E _L ,
It is a function of judging out-of-step by the phase difference.

[0013]

Since the out-of-step protection of the conventional power transmission line protection device requires the voltage information of the other end of the power transmission line, communication equipment is required in addition to the protective relay device, resulting in high cost. There was a problem that became. In addition, there are some transmission line protection devices that realize only the transmission line protection function without communicating with the other end as described above, and such a transmission line protection device has a step-out protection function. Of course, a new communication facility is required to add the device, which increases the introduction cost.

Further, step-out protection in the conventional transformer protection device requires voltage information of both high-voltage side and low-voltage side busbars of the transformer. Initially, the step-out function was not required as a transformer protection device, but after continuing operation for several years, the step-out function is required. It is necessary to add the voltage measurement function on the low voltage side and the low voltage side.

The present invention has been made to solve the above problems, and an object thereof is to realize a step-out protection function of a power transmission line or a transformer with a simple structure.

[0016]

A step-out protective relay according to the present invention is used in a protective relay device of a transmission line connecting a self-terminal and a mating end, wherein the impedance of the transmission line from the self-end to the mating end is used. Characterized in that the voltage at the other end is calculated from the voltage at the own end and the current at the own end, and the out-of-step is determined from the voltage at the own end and the voltage at the other end obtained by the calculation. Is.

Further, the step-out protection relay according to the present invention is used in a protection relay device of a transformer,
Calculate the voltage on the high-voltage side or low-voltage side from the impedance of the transformer, the voltage and current on the high-voltage side or the voltage and current on the low-voltage side of the transformer, and determine the out-of-step from the obtained voltage on both the high-voltage side and the low-voltage side. It is characterized by having done.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a system configuration diagram in which the present invention is applied to a power transmission line protection device, and the same elements as those in FIG. 1
Reference numeral 8 is a self-end step-out protection device provided on the substation α side.
1 is different from FIG. 4 in that communication equipment is not required as a step-out protection function of the transmission line protection device.

FIG. 2 is an explanatory view of the function of the self-end out-of-step protection device 18. That is, it is a block diagram representation of the transmission line out-of-step protection function at the substation α. In FIG. 2, 4
Reference numerals 4 and 45 are a self-end current measuring function and a self-end voltage measuring function for measuring the transmission line current I _α and the bus voltage E _α in the substation at the self-end by using CT _α 8 and PT _α 10, respectively. 48 is the voltage E _β of the other end substation calculated by the following formula from the measured bus voltage E _α at its own end, the transmission line current I _α, and the impedance Z _l to the other end bus 4 which are the measured values. It is the other end voltage conversion function. E _β = E _α −Z _l × I _α

Reference numeral 47 designates the voltage E _α at the self end and the voltage E _β at the other end.
Is a step-out determination function for determining out-of-step, which determines whether or not step-out is performed by the same procedure as in FIG. 6 described in the conventional function, and outputs to the circuit breaker CB _α 12 when it is determined to be out-of-step. To cut off and protect the transmission line 6.

As described above, according to the first embodiment of the present invention, in the power transmission line protection device, the step-out protection function can be realized only by the information of the own end. In addition, if the communication equipment was used for power line protection and out-of-step protection, the bit word for out-of-step protection on the communication equipment and transmission format being used can be used for other purposes. Therefore, the equipment can be used efficiently as a whole. Further, since the out-of-step protection function can be realized in the transmission line protection device that has realized the transmission line protection function without using the communication facility without adding the communication facility, the function can be added at a low cost.

Embodiment 2. The step-out protection relay according to the second embodiment was invented to add only the necessary step-out function when the step-out determination function is added to the transformer protection device. Is to realize at low cost.

Hereinafter, description will be given with reference to FIG. 3 which is a functional explanatory view of the step-out protection relay according to the second embodiment. 3, the same symbols as those in FIG. 8 indicate the same functions.
In the figure, reference numeral 77 denotes a step-out determination function for determining a step-out from the high-voltage side current I _H of the transformer, the high-voltage side voltage E _H, and the transformer impedance Z _T. This is the transmission line protection device of the first embodiment. Only the following points are changed and used in the step-out determination function in.

That is, in the first embodiment, E _α is the voltage E _H on the high voltage side of the transformer, I _α is the current I _H on the high voltage side, and Z _l is the transformer impedance Z _T. The voltage E _L is calculated by the following formula. Then, the step-out determination is performed by using the high-voltage side voltage E _H and the calculated low-voltage side voltage E _L instead of E _α and E _β in the transmission line protection in FIG. In addition, transformer impedance Z
_It is assumed that _T is set in the step-out determination function 77. E _L = E _H −Z _T × I _H As a result, it becomes unnecessary to apply the current and voltage on the low voltage side in FIG.
7 determines that the step-out, issues an output to the CB _H 58, CB _H
Open 58.

The above is an example in which the voltage on the low voltage side is calculated on the high voltage side. However, the voltage on the high voltage side is calculated from the low voltage side current, the transformer impedance, and the low voltage side voltage, and this is used for step out determination. You can also

As described above, according to this embodiment, when the step-out determination function is required as the transformer protection device or when the function of the step-out protection is modified, the voltage on the low voltage side or the high voltage side is changed. There is an effect that the voltage information becomes unnecessary and the device price and the remodeling cost can be provided at a low cost.

[0027]

According to the step-out protection relay according to the present invention, since the step-out protection function can be realized by the information of only the self-end, no communication equipment is required. Also, the communication equipment used for out-of-step protection and the bit words for out-of-step protection on the transmission format can be used for other purposes.
Overall, the equipment can be used efficiently. Also,
Since the out-of-step protection function can be realized in the transmission line protection device that has realized the transmission line protection function without using the communication facility without adding the communication facility, the function can be added inexpensively.

Further, when out-of-step protection as a transformer protection device is necessary or when the step-out protection function is modified,
There is no need for high-voltage or low-voltage voltage and current measurement functions, and there is an effect that the device price and modification cost can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing a power system using a step-out protection relay according to Embodiment 1 of the present invention.

FIG. 2 is a functional explanatory diagram of the step-out protection relay according to the first embodiment of the present invention.

FIG. 3 is a functional explanatory diagram of a step-out protection relay according to Embodiment 2 of the present invention.

FIG. 4 is a system configuration diagram illustrating a conventional transmission line protection device.

FIG. 5 is a functional explanatory diagram of a conventional power transmission line protection device.

FIG. 6 is a diagram illustrating a conventional transmission line out-of-step determination method.

FIG. 7 is a system configuration diagram illustrating a conventional transformer protection device.

FIG. 8 is a functional explanatory diagram of a transformer protection device according to the United States.

[Explanation of symbols]

1 rear equivalent power source, 2 rear equivalent power source, 3 busbars, 4 busbars, 5 equivalent transmission lines, 6 transmission lines, 7 equivalent transmission lines, 8 current transformers, 9 current transformers, 10 instrument transformers, 11 instrument transformers Bowl, 1
2 circuit breakers, 13 circuit breakers,
18 self-end-of-step protection device, 44 self-end current measurement function,
45 self-end voltage measurement function, 47 out-of-step determination function, 48 equivalent transmission line, 49
Equivalent power transmission line, 50 Rear equivalent power supply, 51 Rear equivalent power supply, 52 High voltage side bus bar, 53 Low voltage side bus bar, 5
4 high pressure side current transformer, 55 low pressure side current transformer,
56 high-voltage side instrument transformer, 57 low-voltage side instrument transformer, 58 high-voltage side circuit breaker, 59 low-voltage side circuit breaker, 60 transformer, 61
Transformer protection device, 70 high voltage side current measurement function, 71 low voltage side current measurement function, 72
High voltage measurement function, 74 transformer protection function,
75 Voltage drop judgment function, 77 Step-out judgment function.

Claims (2)

[Claims] 1. A step-out protective relay used in a protective relay device for a transmission line connecting a self-terminal and a remote end, wherein the impedance of the power transmission line from the self-end to the remote end, the voltage at the self-end, and the current at the self-end. A step-out protection relay characterized in that the voltage at the other end is calculated from the voltage and the step-out is determined from the voltage at the other end and the voltage at the other end calculated. 2. A step-out protection relay used for a protection relay device of a transformer, wherein the impedance of the transformer, the high-side voltage and current of the transformer or the low-side voltage and current of the high-side or low-side voltage A step-out protective relay characterized in that a step-out is determined based on the calculated and obtained high-voltage side and low-voltage side voltages.