JP2561734B2 - Transformer internal failure prediction device - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a transformer internal failure prediction device for predicting an internal failure of a transformer such as a pole transformer or an underground transformer provided on a distribution line.

[Prior art]

FIG. 6 is a block diagram showing a conventional power distribution system to which the present invention can be applied, and in the figure, 1 is a main transformer provided in a distribution substation, and 2 is a main transformer. 1 is a bus to which the power output is supplied, L _{1 to} L _n are distribution lines that receive the above power via the bus 2, GPT is an installation transformer connected to the bus 2, OVG is an installation transformer Bowl G
It is a ground fault overvoltage relay operated by zero-phase voltage V ₀ obtained from PT. CB ₁ to CB _n is circuit breaker provided in the distribution line L ₁ ~L _n, CT _s1
To CT _sn current transformer provided on the distribution line _{L 1 ~L n, S 1 ~S} n overcurrent relay which is operated by the current flowing through the current transformer _{CT s1 ~CT sn, ZCT 1 ~ZCT} n is Zero-phase current transformers provided on the distribution lines L _{1 to} L _n , G _{1 to} G _n are grounds operated by the current flowing through the zero-phase current transformers ZCT _{1 to} ZCT _n and the zero-phase voltage V _0. Relay relay, SS
_{11 to} SS _n1 and SS _{12 to} SS _n2 are section switches provided for each predetermined section of the distribution lines L _{1 to} L _n . FIG. 7 is a block diagram showing a drive circuit for operating the circuit breakers CB _{1 to} CB _n . In the figure, AND _{1 to} AND _n are
An OVG operation signal obtained during the operation of the ground fault overvoltage relay OVG is applied to one input terminal, and G ₁ obtained during the operation of the ground fault direction relays G _{1 to} G _n is applied to the other input terminal.
AND gate operation signal ~G _n operation signals are applied respectively, T ₁ through T _n is driven by the output of the AND gate AND ₁ ~AND _n, CB ₁ trip signal-after a certain time to breaker CB ₁ to CB _n CB _n A timer circuit that outputs a trip signal. Next, the operation will be described. Electric power is supplied to each of the distribution lines L _{1 to} L _n from the main transformer 1 of the distribution substation via the bus 2, and this power is supplied to each of the distribution lines L ₁ through the breakers CB _{1 to} CB _n.
It is supplied to a load connected to the respective sections Segmented by ~L _n segments closed opening device _{SS 11 ~SS n1, SS 12 ~SS} n2. In this state, for example, a ground fault has occurred in the distribution line L _1. As a result, the zero-phase voltage V ₀ is obtained from the current limiting resistor connected to the grounding transformer GPT, so that the ground fault overvoltage relay OVG operates and the OVG operation signal is output. At the same time, the ground fault direction relay G ₁ is operated by the zero-phase current from the zero-phase current transformer ZCT ₁ , for example, and the G ₁ operation signal is output. OV above
The G operation signal and the G ₁ operation signal are the AND gate AND of FIG.
_In addition to ₁ , the AND circuit operates the timer circuit T ₁ to output the CB ₁ trip signal. The CB ₁ trip signal is sent to the circuit breaker CB _1, which breaker CB ₁ operates by power distribution line L ₁ is disconnected from the bus 2.

[Problems to be Solved by the Invention]

Since the conventional distribution system is configured as described above,
Although it is possible to respond to the occurrence of actual faults such as ground faults and short circuits, ground faults at the failure prediction stage of pole transformers installed in distribution lines or instantaneous ground faults when reclosing is successful. Since it is impossible to predict an internal failure such as a failure, there has been a problem that it develops into a permanent internal failure of the pole transformer, and an influence such as a power failure due to a distribution line CB trip occurs. The present invention has been made to solve the above problems, and an object thereof is to obtain an internal failure prediction device for a transformer that can predict that an internal failure will occur in the transformer.

[Means for Solving the Problems]

An internal failure prediction device for a transformer according to the present invention includes input waveform analysis data of a zero-phase current and a zero-phase voltage of a distribution system, and pre-registered zero-phase current and zero-phase voltage in a transformer internal failure prediction state. The waveform prediction data is collated, and when a predetermined condition is matched, a failure prediction signal is output.

[Action]

Since the internal failure prediction device for a transformer according to the present invention can know that a failure is likely to occur before the failure actually occurs in the transformer, it is possible to take measures beforehand to prevent a power failure or the like. Can be prevented.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. ZCT ₀₁ ~ZCT _0n the zero-phase current detector for ground fault prediction detection provided for each distribution line L ₁ ~L _n (hereinafter referred to as zero-phase current transformer), the zero-phase current, respectively I ₀₁ ~I Output _0n . CT ₁ to CT _n in current transformer for short-circuit failure prediction detection, and outputs a current I ₁ ~I _n respectively. 3 is a failure prediction calculation unit,
Each current I ₀₁ ~I _0n, with I ₁ ~I _n is applied, the zero-phase voltage detector (hereinafter referred to as grounding transformer) zero-phase voltage V ₀ and the secondary side of the line voltage obtained from the GPT V _S is added. 14
Is a display device including a CRT or the like for displaying the calculation result of the failure prediction calculation unit 3. FIG. 2 is a block diagram showing the configuration of the failure prediction calculation unit 3. In FIG. 2, 4 is the currents I _{01 to} I _0n and I _{1 to} I.
a sample and hold circuit that samples and holds the _n and each of the voltages V ₀ and V _S at a predetermined period,
, 6 is an A / D converter for converting each sample value sequentially obtained from the multiplexer 5 into digital data. The A / D converter 6, the sample hold circuit 4, and the multiplexer 5 are provided. The input part is composed of. 7 is a memory consisting of RAM, A
/ Each current I ₀₁ ~I _0n output from D converter 6 consists of an input waveform data I ₁ ~I _n and voltage V _0, V _S, the input waveform data and the input waveform analysis data waveform analysis Input data is written. Reference numeral 8 is a memory composed of a ROM, which is the waveform data of the current and voltage of each distribution line L _{1 to} L _n in the failure prediction state and the waveform analysis data of the failure prediction state (reference waveform Data for internal failure of pole transformer, which consists of (analysis data) and In addition, when a failure actually occurs, the failure prediction waveform is determined by repeating the work of analyzing the previous waveforms many times to determine a waveform that almost causes the failure. Incidentally, the memory 7 and the memory 8 constitute a storage unit. 9 is a CPU that collates the data of the memory 7 with the data of the memory 8 and performs a predetermined arithmetic processing, 10 is a program memory in which the arithmetic processing program of the CPU 9 is stored, 11 is a bus line that connects the CPU 9 and each unit, 12 is a controller that controls the display device 14 based on the calculation result of the CPU 9, 13 is a process input / output circuit for outputting a failure prediction signal based on the calculation result of the CPU 9, and data collation from the process input / output circuit 13 and the CPU 9 Parts are made up. Next, the operation will be described. Each distribution line L ₁ ~L zero phase at _n current transformer ZCT ₀₁ ~ZCT _0n and current transformer CT ₁ zero-phase current obtained from ~CT _n I ₀₁ ~I _0n, the load current I ₁ ~I _n, ground Transformer G
Zero-phase voltage obtained from the PT V _0, the line voltage V _S is sent to the failure prediction operation unit 3, it is sampled by the sample hold circuit 4. As Figure 3 example the zero phase current I _01, I _02, indicates the state of sampling, by each of which is sampled at a predetermined period, the sample value D ₁₁ is about I ₀₁
DD _{1n, and} sample values D ₂₁ DD _2n for I ₀₂ . These sample values are sequentially taken out by the multiplexer 5, then converted into digital data by the A / D converter 6, and then written into the memory 7. On the other hand, in the memory 8, each zero-phase current I _{01 to} I _0n , zero-phase voltage V ₀ at the time of internal failure of the pole transformer as shown in FIG. 4,
Data for an internal failure of a pole transformer, which is composed of waveform data obtained based on the waveform of the line voltage V _S and its waveform analysis data, is stored in advance. When a ground fault occurs inside the pole transformer, as shown in Fig. 4 (A), I
_{01 to} I _0n and V ₀ change to a singular waveform. The internal failure data of the pole transformer is composed of such waveform data of I _{01 to} I _0n , V ₀ and V _S and its waveform analysis data. Waveform analysis data obtained by analyzing the characteristics of the waveform data, for _{example, I 01 ~I 0n, I 1} ~I n, V 0, the fundamental effective value of the waveform of V _S, the duration, the peak value (p- p value), the size of the DC component,
It is an analysis of several items such as the magnitudes of the harmonic components f _{1 to} f _n and the phase angles of V ₀ and I _{01 to} I _0n . FIG. 4 (B)
Indicates the waveform analysis data. The CPU 9 collates the input data of the memory 7 with the internal failure data of the memory 8, and uses the prediction detection logic shown in FIG. 5 to perform calculation for predicting the internal failure of the pole transformer. In FIG. 5, first, regarding I _{01 to} I _0n of the input data,
It is examined whether or not the respective conditions (0) to (4) shown in the drawing are satisfied. That is, (0) pp of the waveform of I _{01 to} I _0n
Is the value above a certain value, (1) Is the waveform of I _{01 to} I _0n continued for a certain time or more, (2) Is the effective value of the fundamental wave of I _{01 to} I _0n above a certain value? Ika, (3) I ₀₁ ~ I
Is the DC level of _0n above a certain level? (4) I
Check if the effective value of each harmonic of f _{1 to} f _n of _{01 to} I _0n is within the setting range. Then, for each of the I ₀₁ ~I _0n, the (0) to (4) conditions if satisfied all if the outputs a signal YES to the AND gate through the OR gate for each I ₀₁ ~I _0n. Next, with respect to V ₀ , the conditions (0) to (4) above are checked, and if all of them are satisfied, a YES signal is output to the AND gate. Further, regarding V ₀ and I _{01 to} I _0n , it is checked whether or not the respective rising times are within a certain time, and if they are within a certain time, a YES signal is ANDed for each I _{01 to} I _0n.
Output to the gate. From the above, when the respective conditions are satisfied, the failure prediction signal for predicting the internal failure of the pole transformer is output from the AND gate every I _{01 to} I _0n , that is, the distribution lines L _{1 to} L _n.
It is output every time. When the failure prediction signal is output, its contents are displayed on the display device 14. The contents of the display include, for example, current,
The voltage waveform, distribution line name that predicts an internal failure of the pole transformer, prediction detection time, waveform analysis data, etc. are displayed as necessary. In the above embodiment, the example of providing the transformer internal failure prediction device in the distribution substation has been described. Even if it is provided, the same effect can be obtained. Although a dedicated grounding transformer and zero-phase current transformer were used as detectors for zero-phase voltage and zero-phase current, detectors of other detection methods such as optical sensors can be used even if existing equipment is diverted. The same effect can be obtained by using.

【The invention's effect】

As described above, according to the present invention, the input waveform analysis data relating to the input waveform data obtained by sampling the zero-phase voltage and the zero-phase current is collated with the reference waveform analysis data immediately before the internal failure occurs in the transformer. However, since the failure prediction signal is output when the predetermined conditions are met, it is possible to predict the occurrence of a failure before the internal failure of the transformer actually occurs. In addition to being able to take preventive measures to prevent a power failure, even if an internal failure should occur and a power failure should occur, it is possible to recover the failure quickly and easily because the failure location can be identified. This has the effect of enabling reliable power supply.

[Brief description of drawings]

FIG. 1 is a block diagram showing a failure prediction device for a transformer according to an embodiment of the present invention, FIG. 2 is a block diagram of a failure prediction calculation unit of the device, and FIG. 3 is a current sampling state of the device. FIG. 4A is a waveform diagram, FIG. 4A is a waveform diagram of current and voltage at the time of internal failure of the transformer of the device, FIG. 4B is a waveform analysis data diagram, and FIG. 5 is failure prediction detection of the device. FIG. 6 is a block diagram showing a logic, FIG. 6 is a block diagram showing a conventional power distribution system, and FIG. 7 is a block diagram showing a drive circuit of a circuit breaker of the power distribution system. 2 is a bus bar, L _{1 to} L _n are distribution lines, GPT is a grounding transformer, ZCT ₀₁
~ ZCT _0n is a zero-phase current transformer, 3 is a failure prediction calculator, 7 and 8 are memories, and 9 is a CPU. In the drawings, the same reference numerals indicate the same or corresponding parts.

Front Page Continuation (72) Inventor Koichiro Oyabu 2-47 Shiobara, Minami-ku, Fukuoka City, Fukuoka Prefecture Kyushu Electric Power Co., Inc. Research Institute, Electric Power Laboratory (72) Inventor Akira Kaneda Wadazaki, Hyogo-ku, Kobe-shi, Hyogo Prefecture 1-2 1-2, Mitsubishi Electric Co., Ltd. Control Works (72) Inventor Toshinobu Ebisaka 1-2-1, Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Co., Ltd. Control Works (72) Inventor Keiji Isahaya 1-2, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Electric Corporation Control Factory (56) Reference JP-A-63-224622 (JP, A)

Claims (1)

(57) [Claims] 1. A zero-phase voltage detector for detecting a zero-phase voltage of a distribution system fed from a transformer, a zero-phase current detector for detecting a zero-phase current of the distribution system, and the zero-phase voltage detector. An input section for sampling the zero phase voltage detected by the zero phase current and the zero phase current detected by the zero phase current detector as input waveform data, and input waveform analysis data related to the input waveform data sampled by the input section. At the same time, the storage unit that stores the reference waveform analysis data immediately before the internal failure occurs in the transformer, the input waveform analysis data and the reference waveform analysis data stored by the storage unit are collated, and the predetermined condition is An internal failure prediction device for a transformer, comprising: a data verification unit that outputs a failure prediction signal when they match.