KR20000007462U - Digital protective relay with automatic detection of operating elements - Google Patents

Abstract

The present invention relates to a digital protective relay having an automatic detection function of the operating element, and more specifically, to detect the amount of electricity related to the instantaneous and / or temporary operating element from the actual power system, and based on the abnormality of the power system The present invention relates to a digital protection relay for instantaneous and / or temporary protection of a power system more accurately than conventionally. The controller provided in the digital protection relay controls the operation of the corresponding load in the power system when the setup mode according to the user's key operation is applied, and checks the amount of electricity from the load system accordingly. After extracting the rated electric power of the corresponding load in relation to the, it is determined whether the load system abnormality based on this. The signal processing unit filters, sample-holds, and analog / digital converts an electric signal generated from the load system according to the rated operation control of the controller and supplies it to the controller. Thus, the present invention provides an effect of more precisely instantaneous and / or time-out protection of the power system by extracting the rated electric quantity of the corresponding load from the actual power system and setting a correction value based thereon.

Description

Digital protective relay with automatic detection of operating elements

The present invention relates to a digital protective relay having an automatic detection function of the operating element, and more specifically, to detect the amount of electricity related to the instantaneous and / or temporary operating element from the actual power system, and based on the abnormality of the power system The present invention relates to a digital protection relay for instantaneous and / or temporary protection of a power system more accurately than conventionally.

In today's highly industrial society, the stable supply of electrical energy has emerged as the most important role of water distribution facilities. Accordingly, the conventional induction disk type protection relay is being replaced with a digital protection relay using a microprocessor. The protection relay is not necessary when the power system of the power distribution equipment is in operation without any abnormality.However, if an abnormal condition such as a short circuit, ground fault, or opening occurs, the above-mentioned protection relay immediately responds to the posture for protecting the power system according to the purpose of use. Get drunk. More specifically, the protection relay immediately determines when an abnormal condition occurs in the power system of the plant and various equipments, and quickly cuts off the power supplied to the load so that the above-mentioned abnormal state spreads to the normal facilities of the power system. In order to prevent this, various protective relays such as over / under voltage relays, instantaneous / temporary overcurrent relays, and ground type relays are used.

On the other hand, when the above-mentioned abnormal state occurs, the protection relay takes the appropriate posture is said to 'correct the protective relay,' at this time, the reference value to take the posture is referred to as 'correction value'. In order to correct the protective relay, (1) the power system configuration (all loads using electricity such as generators, transformers, motors, and other distribution systems) necessary for the calculation of current and / or voltage in abnormal conditions, (2) all loads and distribution systems (3) Protective relay method and sequence drawing are required. In the related art, a method of correcting the correction value of the protection relay was taken after installing an appropriate protection relay by roughly calculating the rated current and the impedance of the cable constituting the system in consideration of the above-mentioned matters. For example, when a large-capacity motor is used as a load, the rated current value, which is the basic data of correction, is calculated and calculated in consideration of the above-mentioned matters, and 1.2 times of the calculated rated current value is estimated as an overload condition and set as a correction value. Accordingly, the digital protection relay determines that the current is detected from the load system associated with the motor during the actual operation of the motor and exceeds the above-described correction value for a predetermined time, and determines that it is an overload condition and applies the skip signal to the circuit breaker. To cut off the power supply.

However, in the related art, the electrical protection (rated current and / or rated voltage) related to instantaneous and / or time-limiting protection operation elements is calculated from the power system diagram outlined according to experience or estimation rather than accurate design data, and based on the digital protection relay By setting the correction value of, it is different from the actual amount of electricity (rated current and / or rated voltage) measured in a complex power system, which causes a problem that the power system cannot be protected accurately. More specifically, even though it is not necessary to actually cut off the power system, the operation can be interrupted due to blocking. On the contrary, even though the power system must be cut off, it is not blocked, which is critical to the corresponding load of the power system. The problem is that it can cause loss.

The purpose of the present invention to solve this problem is to extract the amount of electricity related to the operating element of the protective relay from the actual power system, not calculated value, and based on the digital correction that can more accurately protect the power system To provide a protective relay.

1 is a block diagram showing a digital protective relay having an automatic detection function of the instantaneous and / or time limiting operation element according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: signal conversion unit 10a: auxiliary signal conversion unit

10b: filter circuit 10c: sample holding circuit

10d: Multiplexer 10e: A / D converter

10f: Buffer 10g: Clock Generator

12: controller 14: key input unit

16 memory 18 display unit

Digital protection relay having an automatic detection function of the operating element according to the present invention for achieving the above object, in the digital protection relay for protecting the power system, the power system when the setup mode according to the user's key operation is applied It controls to operate the corresponding load within the rated load, checks the amount of electricity from the load system according to this, extracts the rated electric power of the corresponding load related to the instantaneous and / or temporary operation element, and judges whether the load system is abnormal based on this. controller; And a signal processing unit for filtering, sample-holding, and analog / digital conversion of an electric signal generated from the load system according to the rated operation control of the controller and supplying it to the controller. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the digital protection relay according to the present invention includes a signal processor 10 and a controller 12. First, the key input unit 14 applies a set-up mode key signal to the controller 12 according to a user's key operation. Here, the setup mode according to the present invention is to check the amount of electricity supplied from the actual power system to extract the rated electricity (rated current and / or rated voltage) related to instantaneous and / or time-limited protection of the power system, based on the digital protection This is to set the correction value of the relay. The controller 12, which may be implemented as a microprocessor or a programmable logic controller 12 (PLC), generates a rated operation control signal in response to a setup mode key signal applied from the key input unit 14. The load is controlled to operate at the rated load of the power system by starting the load. Here, the rated operation means to operate so that the amount of electricity (current and / or voltage) detected from the load system during the load operation considering the load characteristics of the system maintains a stable value for a predetermined time.

When the corresponding load is started according to the operation control of the controller 12, the CT (Current Transformer) and PT (Power Transformer), which are not shown in the power system, respectively, convert the amount of electricity from the load system, so that current and voltage as secondary outputs are converted. ( I _a, I _b, I _c, I _d, V _a, V _b, V _c, V _d ) Is supplied to the signal processor 10 of FIG. 1.

The signal processing unit 10 corresponds to the auxiliary signal conversion unit 10a, the filter circuit 10b, the sample holding circuit 10c, and each load system configured to correspond to each load system a, b, c, d. A multiplexer 10d for multiplexing current and voltage, an analog / digital (A / D) converter 10e, a buffer 10f, and a clock generator 10g are provided. The auxiliary signal converting unit 10a converts the AC signal, which is the secondary output of the CT and PT, into a DC signal and converts it into an electrical signal that can be accepted by the digital relay unit of the next stage. The filter circuit 10b is composed of a low pass filter that removes noise contained in the high frequency band and the harmonic signal of the analog signal from the auxiliary signal conversion unit 10a. The sample holding circuit 10c samples-holds the output signal of the filter circuit 10b. The multiplexer 10d multiplexes corresponding currents and voltages for each load system from each sample holding circuit 10c. The analog / digital converter 10e converts the multiplexed analog electrical signal from the multiplexer 10d into a digital electrical signal. The buffer 10f buffers the digital electrical signal from the analog / digital converter 10e. At this time, the clock signal generated from the clock generator 10g is applied to the multiplexer 10d, the analog / digital converter 10e, and the buffer 10f to enable the operation of each component. Digital data of current and voltage measured from the load system, stored in the buffer 10f, is supplied to the controller 12.

The controller 12 continuously checks the amount of electricity (current and / or voltage) supplied from the signal processor 10. If the check result does not maintain the predetermined stable value for a predetermined time, the controller 12 determines that the load is not rated at the rated operation state, and repeatedly executes the load until the amount of electricity from the checked load is maintained for a predetermined time. Control to drive. On the other hand, if the check result indicates that the electricity amount from the load system is stable for a predetermined time, the controller 12 determines that the load is in the rated operation state, and the detected electric quantity is the rated electricity amount (rated current and / or rating) of the load. Voltage). The controller 12 sets a correction value in the memory 16 for instantaneous and / or time-limited protection of the power system based on the rated electric quantity extracted from the actual power system. The controller 12 outputs the extracted rated electric quantity (rated voltage and / or rated voltage) to the display unit 18 to the user. When the setting and display of the correction value is completed based on the rated electric power extracted from the actual power system, the user cancels the setup mode and performs the normal operation of the equipment of the power system. Accordingly, the controller 12 performs the unique function of the instantaneous and / or the time limit protection of the power system based on the correction value based on the rated electric quantity extracted from the actual power system in consideration of the load characteristics. Compared to politics, instantaneous and / or time-limited protection of power systems can be achieved.

On the other hand, the present invention can be applied to all types of digital protection relay to protect the power system on the basis of the correction value, and thus the rated electric power extracted from the actual power system is not limited to the rated current and / or rated voltage. Do not. Therefore, it will be apparent to those skilled in the art that other modified embodiments, which are not mentioned with reference to the technical spirit and preferred embodiment of the present invention, may be easily implemented, and thus the detailed description thereof will be omitted.

As described above, the digital protective relay having the automatic detection function of the operating element according to the present invention has a rated electric quantity (rated current and / or rated voltage) extracted from the actual power system according to the rated operation for a predetermined time considering the load characteristics. By setting the correction value, which is a reference value for instantaneous and / or time limit protection of the power system, the more accurate correction value can be set. In particular, as the power system becomes more complicated, the reliability of the setting value is significantly increased compared to the conventional method. . In addition, the present invention displays the rated electric power extracted according to the rated operation of the load to the user to check the reliability of the rated electric power (rated voltage or rated current) suggested by the manufacturer, such as a high voltage motor or a power transformer. At the same time, it is possible to design the power system based on the rated electric power from the actual power system, thereby ensuring the accumulation of design technology and reliability. As a result, the present invention provides an effect of more accurately protecting the power system than in the prior art.

Claims (4)

In the digital protection relay to protect the power system, When the setup mode according to the user's key operation is applied, the corresponding load in the power system is controlled to be rated, and accordingly the electric power from the load system is checked to extract the rated electric power of the corresponding load related to the instantaneous and / or temporary operation elements. After that, the controller for determining whether or not the load system based on this; And And a signal processing unit for filtering, sample-holding, and analog / digital conversion and supplying the electric signal generated from the load system according to the rated operation control of the controller to supply the controller to the controller. The method of claim 1, wherein the controller It is checked whether the amount of electricity of the load supplied from the signal processing unit maintains a stable value for a predetermined time. If the check result does not maintain the stable value, the control is repeated to operate the load until the stable value is maintained. And if the amount of electricity is extracted as the rated electricity of the load. The method of claim 1, wherein the controller And a correction value for instantaneous and / or time-limited protection of the load system based on the extracted rated electric quantity, and storing the correction value in a memory. The digital protective relay as claimed in claim 1, wherein the controller controls the display unit to further output the extracted rated electric power of the corresponding load.