JP2002095149A - Semiconductor switch control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the accuracy of accident detection and prevent malfunction as much as possible while ensuring the high speed of the interruption operation in the event of a true accident. SOLUTION: An accident determination numerical value conversion circuit 26 receives first and second state quantities and converts them into numerical values suitable for determining the presence or absence of an accident. First to Nth accident determination circuits J1
.. JN input the converted numerical values and judge whether or not an accident has occurred. Control signal output circuit 27
Outputs an interruption command 20 to the semiconductor switch when an accident occurrence determination signal is input from any of the determination circuits.
The accident judging circuit J1 has the lowest voltage judging bell and the shortest judging time.
N has the highest voltage determination level and the longest determination time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switch control device which detects an accident occurring in two systems linked via a semiconductor switch and controls a switching operation of the semiconductor switch.

[0002]

2. Description of the Related Art FIG. 13 is a diagram showing a cooperative configuration of two power receiving / power supply systems. In this figure, a power receiving / power supply system 1 and a power receiving / power supply system 2 are connected via a semiconductor switch 3. Power receiving / power supply system 1
Has a link transformer 5 and a general load 7 connected to a commercial load bus 6, and connects a power supply from a commercial system (a power company system, also referred to as a power purchase system) 4 to the link transformer. The general load 7 can be received via the terminal 5.
The power receiving / power supply system 2 has a private generator 8 connected directly to the generator bus 10 or via a transformer 9, and a private load 11 also connected to the generator bus 10.

The power receiving / power supply system 1 and the power receiving / power supply system 2 are used, for example, in factories or hospitals of a certain company, and the self-generated load 11 is an important power that cannot be stopped even instantaneously. Since they are loads, all of them are supplied with electric power from the private generator 8. On the other hand, since the general load 7 has a lower importance than the self-generated load 11, the surplus power of the private generator 8 is supplied through the semiconductor switch 3, and the supply of the insufficient power is supplied to the commercial load. It is designed to receive from system 4. Although FIG. 13 illustrates an example in which two power receiving / power supply systems 1 and 2 are linked, these systems are conceptually shown, and a system in which a plurality of systems are aggregated may be used. Contains. Therefore, the present invention describes a semiconductor switch control device applied to two linked systems for ease of explanation and understanding. However, in practice, three or more systems are linked. It is also applicable to:

FIG. 14 is a configuration diagram of the semiconductor switch 3 in FIG. As shown in this figure, the semiconductor switch 3 has a U / X thyristor arm 12, a V / Y thyristor arm 13, and a W / Z thyristor arm 14, and the thyristor of each of these arms is a semiconductor switch control device 15 On / off control is performed by a gate signal 16 from the CPU. FIG. 13 shows that the AC power is 3
Although the configuration of the semiconductor switch 3 in the case of the three phases is shown, the present invention is applicable to AC power other than three phases.
FIG. 13 shows an example in which a thyristor is used as a semiconductor element. However, the semiconductor element is not limited to a thyristor. If the semiconductor element functions as a switching element, a transistor, a triac, a GTO, an IG
Other elements such as BT may be used.

FIG. 15 is a block diagram showing a configuration of a semiconductor switch control device 15 for controlling the semiconductor switch 3. As shown in FIG. The semiconductor switch control device 15 shuts off the on-state semiconductor switch 3 at a high speed when an accident (for example, a short-circuit accident such as a ground fault due to a lightning strike) occurs on the power receiving / power supply system 1 side. is there.

Here, the reason why the semiconductor switch 3 must be turned off at high speed when a short circuit accident occurs on the power receiving / power supply system 1 side will be described. If a short-circuit fault occurs on the power receiving / power supply system 1 side when the semiconductor switch 3 is in the ON state, a large amount of current on the power receiving / power supply system 2 side flows into the short-circuit fault point. Drops sharply. And generator bus 1
If the state where the voltage of 0 drops below a certain level is maintained for a certain period of time, the self-generated load 11 which is an important load
Will cause serious effects such as stoppage or malfunction. In particular, power electronics applied equipment is generally susceptible to the voltage drop. For example, if the rated voltage of 0.85 PU or less is maintained for 10 ms or more, the above-described stop or malfunction often occurs. For such a reason, when a short circuit accident occurs on the power receiving / power supply system 1 side, it is necessary to rapidly shut off the semiconductor switch 3 which is in the ON state.

Returning to FIG. 15, the semiconductor switch control device 15 includes an accident detection circuit 19, an opening / closing determination means 21, an interlock circuit 24, and a gate control circuit 25. The fault detection circuit 19 receives detection signals from a CT (current transformer) 17 and a PT (instrument transformer) 18 provided on the commercial load bus 6, and when a short-circuit fault occurs, a current from the PT 18 is input. Upon detecting that the detection signal has dropped to a level equal to or lower than the threshold value, the cutoff command 20 is output to the interlock circuit 24. The open / close determining means 21 includes an open circuit command 22 as an operation start command,
And a closing command 23 as an operation stop command is output to the interlock circuit 24. Interlock circuit 24
Interlocks these commands and sends one of them to the gate control circuit 25. The gate control circuit 25 outputs the gate signal 16 when the open circuit command 22 is input, and turns the semiconductor switch 3 on, that is, on. The gate control circuit 25
When the closing command 23 or the cutoff command 20 is input, the output of the gate signal 16 is stopped, and the semiconductor switch 3 is turned off, that is, turned off. And the semiconductor switch 3
In, the current is actually interrupted after the current passes through the zero-cross point.

FIG. 16 shows the signals ((a) to (e)) of the semiconductor switch control device 15, the voltage (f) and the current (g).
FIG. 6 is a waveform chart showing a correspondence relationship with the above. When the closing command 23 is output and the gate signals U and X are output at time t0, energization is started as shown by the switch current waveform (g). Then, when a ground fault due to a lightning strike occurs at time t1, for example, the voltage rapidly drops to near zero as shown in (f). The accident detection circuit 19
The occurrence of an accident is detected by this voltage drop, and a shutoff command 20 is output at time t2, whereby the gate signals U,
Stop the output of X. As a result, the switch current reaches the zero-cross point at time t3 as shown in (g).
Is shut off at

FIG. 16 shows changes in voltage and current for one phase of three-phase alternating current. FIG. 17 shows changes in voltage and current for three phases. As shown in (a), when the semiconductor switch 3 is turned on at time t0, the switch current of each phase flows in a stable state for a while, but when an accident occurs at time t1, an overcurrent flows into the accident point. Therefore, the current level sharply increases, and thereafter, the current is cut off at time t3. As shown in (b), the voltage of each phase on the system 1 side is disturbed after time t1, and then the voltage becomes zero at time t3. As shown in (c), the voltage on the system 2 side is disturbed due to the accident during the time t1 to t3, but thereafter, the semiconductor switch 3 is turned off and the system 1 is disconnected. Therefore, it will be in the same stable state as before the accident. (D) shows a change state of the active power of the private generator 8, which fluctuates greatly due to the occurrence of an accident.
Is turned off, and then returns to a stable state.
(E) shows the changing state of the gate signal of each phase. The gate is turned on at time t0 and then turned off at time t2.

[0010]

As described above, when the conventional semiconductor switch control device 15 detects a short-circuit accident on the power receiving / power supply system 1 side, it shuts off the semiconductor switch 3 at a high speed, and a private load which is an important load. The influence of the accident on the generated load 11 is avoided. However, in order to shut off the semiconductor switch 3 at high speed, it is necessary to perform an accident determination in a short time. In that case, there is a high possibility that an accident is erroneously detected. For example, as a normal operation in system operation,
The turning on / off of the general load 7 or the phase adjustment equipment is performed as needed. If the voltage drop at this time falls below the set level and the state of falling below the set level continues for more than the set time, the semiconductor switch control device 15 may fail. Is determined to have occurred,
The semiconductor switch 3 is cut off.

As a basic concept in system design,
A mistake that mistakenly deems this to be no accident even though an accident has actually occurred is a “dangerous mistake” and is a mistake that is absolutely unacceptable. However, a mistake that mistakenly identifies this as having an accident is a “safety mistake” and is considered to be a mistake that can be tolerated to some extent. Therefore, the set level is set to be higher and the set time tends to be set shorter, so that the semiconductor switch control device 15 is sensitive to a voltage drop on the power receiving / power supply system 1 side. A voltage drop at the time of turning on / off the general load 7 or the phase adjustment equipment or a voltage drop caused by noise is erroneously recognized as an accident, and the malfunction of shutting off the semiconductor switch 3 is often performed. Has become. Such a malfunction is a "safety mistake", and although it can be tolerated to some extent, if it occurs too frequently as a practical problem, the system will not be practically usable.

The present invention has been made in view of the above circumstances, and it is possible to increase the accuracy of accident detection and prevent malfunctions as much as possible while ensuring the high speed of the interruption operation in the event of a true accident. It is an object to provide a semiconductor switch control device.

[0013]

As means for solving the above-mentioned problems, the invention according to claim 1 is provided on a bus connecting the first power receiving / power supply system and the second power receiving / power supply system. A semiconductor switch for switching the connection state between the two systems and controlling the switching operation based on a detection result of an accident occurring in one of the two systems;
An accident determination numerical conversion circuit for inputting a state quantity from the first or second power receiving / power supply system and converting the input into a numerical value suitable for determining the presence or absence of an accident; and A plurality of accident judgment circuits for inputting numerical values and outputting judgment results based on different judgment levels,
A control signal output circuit that outputs a control signal to the semiconductor switch based on the input of the determination result from the plurality of accident determination circuits.

According to the above configuration, since the state quantity from the system is not used, but converted into a numerical value suitable for judging the presence or absence of an accident, the accuracy of accident judgment can be improved, and a malfunction can be effectively performed. Can be prevented. Further, since a plurality of fault determination circuits are provided, the semiconductor switch can be shut off at an optimum timing according to the situation of the system fault. In other words, it is possible to achieve both high-speed shut-off of the semiconductor switch and prevention of malfunction.

According to a second aspect of the present invention, in the first aspect of the present invention, the first power receiving / power supply system has a general load that is always supplied with power from a commercial system, and The power receiving / power supply system is characterized in that it always receives power supply from a private power generator and has a private load as an important load.

According to the above configuration, when an accident occurs on the first power receiving / power supply system side, the semiconductor switch is immediately turned off, thereby affecting the important load on the second power receiving / power supply system side. Can be avoided.

According to a third aspect of the present invention, in the first or second aspect of the invention, each of the plurality of accident determination circuits outputs a determination result as the determination level approaches a serious accident occurrence level. The time until the time is short.

According to the above configuration, it is possible to reliably perform an accident determination with a sufficient time for a relatively light accident, and to perform an accident determination at a high speed for a serious accident. That is, the semiconductor switch can be shut off at an appropriate timing according to the degree of the impact of the accident.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the state quantity input to the accident determination numerical conversion circuit is a bus voltage on the first power receiving / power supply system side. Features.

According to the above configuration, it is possible to quickly detect a short circuit accident or a ground fault accident due to lightning strike on the first power receiving / power supply system side, and cut off the semiconductor switch to thereby provide the second power receiving / power supply. The system can be protected.

According to a fifth aspect of the present invention, in accordance with the third aspect of the present invention, the plurality of fault judging circuits include a first fault judging circuit for outputting a judgment result at a high speed based on a first voltage judgment level; And a second fault judgment circuit that outputs a judgment result at a low speed based on a second voltage judgment level set higher than the first voltage judgment level.

Although it seems that various types of accidents can be dealt with as the number of accident judgment circuits increases, if the number of accident judgment circuits increases beyond a certain level, the operation speed becomes slower and rapid semiconductor switch control becomes impossible. In the above configuration, the first type for performing the high-speed determination is
Since only two of the above-mentioned fault determination circuit and the second fault determination circuit for performing low-speed determination are provided, the semiconductor switch can be controlled sufficiently quickly.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the state quantities inputted by the accident determination numerical value conversion circuit are first and second two kinds of state quantities. Each of the plurality of accident determination circuits outputs a first determination result based on the first state quantity, and outputs a second determination result based on the second state quantity. And an element determination output unit that outputs a logical product of the first and second determination results to the control signal output circuit as the determination result. I do.

According to the above configuration, the change in the two types of state quantities is monitored, and the presence or absence of an accident is determined based on the logical product of the two determination results. The change can be identified, and the determination accuracy can be further improved.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, the first state quantity is an instantaneous voltage value at a predetermined point in the system, and the second state quantity is a predetermined voltage in the system. An instantaneous current value at a point, wherein the first determination means outputs an accident occurrence level signal as the first determination result when the instantaneous voltage value becomes equal to or less than a set value, and performs the second determination. Means for outputting an accident occurrence level signal as the second judgment result when the instantaneous current value exceeds a set value, and the element judgment output means outputs an accident occurrence level signal based on a logical product of these two accident occurrence level signals. Outputting an occurrence determination signal to the control signal output circuit.

When a ground fault or the like occurs, the state quantities that change most remarkably are the voltage and the current. Therefore, according to the above-described configuration, it is possible to improve the accuracy of determination at the time of the occurrence of these faults.

[0027] According to an eighth aspect of the present invention, in the first aspect of the invention, the power supplied to the first and second power receiving / power supply systems is AC power, and the accident determination is performed. The numerical value conversion circuit inputs the current instantaneous values of each phase as the state quantity, converts them into absolute values, and sets the maximum value of these absolute values to a numerical value suitable for determining the presence or absence of the accident. And a current calculation circuit for outputting to the plurality of accident determination circuits.

According to the above configuration, since the accident determination is performed based on the maximum value of the instantaneous current value of each phase of the AC power, the accident determination at the time of occurrence of a ground fault or the like can be performed quickly and reliably. .

According to a ninth aspect of the present invention, in accordance with the first aspect of the present invention, each of the plurality of fault judging circuits is connected to the output side of each of the fault judging circuits so that each fault judging circuit continues for a predetermined time. Only when a judgment result indicating
A confirmation time limit circuit that permits outputting the determination result to the control signal output circuit is connected.

According to the above configuration, since the confirmation time-limit circuit is provided, even if the state quantity temporarily exceeds the level of the occurrence of the accident due to noise or other fluctuation factors, the semiconductor is immediately mistaken for the occurrence of the accident, and the semiconductor is determined to be incorrect. It is possible to prevent the switch from being shut off.

The invention described in claim 10 is the invention according to claims 1 to 9
In the invention described in any one of the above, a filter circuit for removing a high-frequency component is connected to each input side of the plurality of accident determination circuits.

According to the above configuration, it is possible to remove the influence of harmonics and noise accompanying the input state quantity. Further, even when each circuit is configured using a microcomputer, the influence of ripple components and the like due to sampling can be removed, and erroneous detection at the time of accident determination can be prevented.

According to an eleventh aspect of the present invention, in accordance with the seventh aspect of the present invention, a signal for continuously outputting the accident occurrence level signal to the element determination output means at an output side of the second determination means for a predetermined time. A holding circuit is connected.

According to the above configuration, even if it is difficult to determine an accident due to the influence of the power receiving / power supply system after the occurrence of the accident or the characteristics of the equipment, a reliable judgment can be made.

The twelfth aspect of the present invention is the first aspect of the present invention.
The invention according to any one of the first to third aspects, further comprising an external interface circuit that outputs an accident occurrence detection signal to the control signal output circuit based on an input signal from a predetermined external device,
The control signal output circuit outputs a control signal for the semiconductor switch immediately when the accident occurrence detection signal is input.

With the above configuration, when the external device detects that the semiconductor switch should be shut off, the semiconductor switch can be quickly shut off immediately without waiting for an accident judgment by the present device. .

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an accident detection circuit 19A which is a main part of the first embodiment. The configuration of the semiconductor switch control device according to the first embodiment is similar to that of the semiconductor switch control device 15 shown in FIG.
1 is replaced with an accident detection circuit 19A of FIG.

In FIG. 1, an accident detection circuit 19A includes an accident judgment numerical conversion circuit 26 and N circuits, that is, a first circuit.
To an Nth accident determination circuit J1 to JN, and a control signal output circuit (OR circuit) 27. The accident determination numerical value conversion circuit 26 receives the first state quantity or the second state quantity from the power receiving / power supply system 1 or the power receiving / power supply system 2, and converts this into a numerical value suitable for determining whether or not an accident has occurred. Things. In this embodiment, it is assumed that the first and second state quantities are a voltage and a current (instantaneous value) input from the power receiving / power supply system 1 via the CT 17 and the PT 18 and the like. In addition, various values may be considered as values suitable for determining whether or not an accident has occurred. In addition to voltage and current, for example, frequency, active power, and reactive power may be used. In this embodiment, a case where an effective value voltage is used will be described as an example.

The numerical values converted from the instantaneous voltage to the effective value voltage by the accident judgment numerical value conversion circuit 26 are input to the first to N-th accident judgment circuits J1 to JN. A judgment level for judging a system accident condition is set in each accident judgment circuit. In this case, the judgment level of each accident judgment circuit is
The levels are different according to the severity of the detected accident. For example, for a serious accident (an accident in which the system voltage level is almost zero, such as a ground fault caused by lightning), the voltage judgment level is set to the lowest level, while a minor accident (when the system voltage is slightly In the case of a small accident that causes a drop, the voltage determination level is set to be relatively high.

Further, the first to N-th accident judging circuits J1
The judgment times JN are different from each other depending on the severity of the detected accident. For example, in the case of a serious accident, it is required to shut off the semiconductor switch 3 as quickly as possible so as not to increase the influence on the self-generated load 11 which is an important load. On the other hand, in the case of a minor accident, the effect on the self-generated load 11 side is small, so it is not necessary to shut off the semiconductor switch 3 so quickly, but rather to confirm that the accident has occurred. It is preferable that a sufficient time is provided to ensure that the cutoff is performed.

As described above, the judgment levels and the judgment times of the first to Nth accident judgment circuits J1 to JN are different from each other, and the first accident judgment circuit J1 judges the most serious accident. And an N-th accident determination circuit JN is a circuit for determining the smallest accident. That is, the first accident determination circuit J1
The voltage judgment bell is the lowest and the judgment time is the shortest, while the N-th accident judgment circuit JN has the highest voltage judgment level and the longest judgment time.

Each of the judgment results of the first to N-th accident judgment circuits J1 to JN is inputted to a control signal output circuit 27 constituted by an OR circuit. When the control signal output circuit 27 receives a judgment signal indicating that an accident has occurred from any of the first to Nth accident judgment circuits J1 to JN, the control signal output circuit 27 controls the shutoff command 20 through the interlock circuit 24 to perform gate control. The signal is output to the circuit 25.

Next, the operation of FIG. 1 will be described. The accident determination numerical conversion circuit 26 always receives the instantaneous voltage value and instantaneous value from the power receiving / power supply system 1 as the first and second state quantities, and converts them into the effective voltage value and the effective current value. And outputs the signals to the first to Nth accident determination circuits J1 to JN. Now, considering a case where a ground fault due to a lightning strike occurs in the power receiving / power supply system 1, the first to N-th accident determination circuits J1 to JN compare these input values with respective determination levels, Although the judgment result is output within each judgment time, it is the first accident judgment circuit J1 that outputs the judgment signal of the occurrence of the accident at the shortest time. The control signal output circuit 27, when first inputting the accident occurrence determination signal from the first accident determination circuit J1, outputs this as a cutoff command 20 to the gate control circuit 25 via the interlock circuit 24. Thereby, the gate control circuit 2
The output of the gate signal from 5 is stopped, and the semiconductor switch 3 is turned off. After the first accident judgment circuit J1 outputs the accident occurrence judgment signal, the second to Nth accident judgment circuits J2 to JN sequentially output the accident occurrence judgment signals, but the first accident judgment circuit J1 has already been output. Outputs an accident occurrence determination signal, and the semiconductor switch 3 is shut off. Therefore, these later output accident occurrence determination signals have substantially no effect.

On the other hand, considering the case where the smallest accident occurs in the power receiving / power supply system 1, the first to (N-1) th accident judgment circuits J1 to JN- in which the voltage judgment level is set to a higher level are considered. 1 does not output an accident occurrence judgment signal,
Only the N-th accident judgment circuit JN whose voltage judgment level is set to be the lowest outputs the accident occurrence judgment signal. Since the judgment time of the N-th accident judging circuit JN is long (that is, the judgment is performed by taking a long time), an accident occurrence judging signal is output due to a temporary voltage fluctuation at the time of load application. And does not cause a malfunction.

As described above, the accident detection circuit 19A shown in FIG.
In, the instantaneous voltage value of the power receiving / power supply system 1 is converted by the accident determination numerical value conversion circuit 26 into an effective voltage value. When the effective voltage value is extremely lowered, the first accident judgment circuit J1 (or a circuit whose judgment level is close to J1) outputs an accident occurrence judgment signal at a high speed, while the voltage effective value is reduced. In the case where the decrease is small, the N-th accident judging circuit JN (or a circuit whose judgment level is close to JN) outputs an accident occurrence judging signal which is carefully judged with time. I have. Therefore, it is possible to output an accident occurrence determination signal at an optimal timing according to the situation of the system accident, and to improve the accuracy of accident detection while minimizing malfunctions while securing the high speed of the shutoff operation of the semiconductor switch 3. It becomes possible.

FIG. 2 is a block diagram showing a configuration of an accident detection circuit 19B which is a main part of the second embodiment. FIG. 2 is different from FIG. 1 in that the number of accident judgment circuits is limited to only two, that is, a first accident judgment circuit J1 and a second accident judgment circuit J2. The more the number of the accident determination circuits, the more detailed the judgment can be made, so that it is possible to cope with various types of accidents, and it seems preferable at first glance. However, as the number of accident determination circuits increases, the processing becomes more complicated. Further, when an accident determination circuit is configured by a microcomputer, there is a restriction that the accident determination process must be completed within a sampling time, and thus the number of circuits that can actually be increased is limited. Therefore, in the present embodiment, a case where the number of accident determination circuits is two will be described as the simplest example.

The first accident judgment circuits J1, J2 in FIG.
In, the determination level is set by focusing on the voltage applied to the self-generated load 11, which is an important load. In other words, the first accident judgment circuit J1 outputs an accident occurrence judgment signal when a voltage effective value such that the voltage applied to the self-generated load 11 falls below 90% of the rated value for a set time. On the other hand, the second accident judging circuit J2 outputs an accident occurrence judging signal when a voltage effective value such that the applied voltage of the self-generated load 11 becomes 90 to 95% of the rated value is input for a set time. It is supposed to.

This is because, in a normal power electronic device, the applied voltage at which a normal operation is guaranteed when a voltage fluctuation occurs is within ± 10% of the rating, so that the voltage drop exceeding the guaranteed range is avoided. On the other hand, the confirmation time is almost zero, and the semiconductor switch 3 is instantaneously cut off. In addition, if the applied voltage is within ± 10% of the rated voltage fluctuation, that is, the voltage fluctuation within the guaranteed range, the self-generated load 11 is not immediately adversely affected, and the determination is made to some extent. Better.
This is because there is a possibility that a malfunction may occur due to a voltage fluctuation when the general load 7 or the phase adjustment facility on the power receiving / power supply system 1 is turned on / off. However, if the applied voltage is a small voltage fluctuation that does not fall below 95% of the rating,
It is not necessary to shut off the semiconductor switch 3, and it is better to keep the link as it is. Therefore, as mentioned above,
The second accident judging circuit J2 outputs an accident occurrence judging signal when an effective voltage value such that the voltage applied to the self-generated load 11 becomes 90 to 95% of the rated value is input for a set time. ing.

FIG. 3 is a block diagram showing a configuration of an accident detection circuit 19C which is a main part of the third embodiment. In this accident detection circuit 19C, the accident determination numerical conversion circuit 26 has a voltage operation circuit 28 and a current operation circuit 29,
Each of the fault judging circuits J1 to JN has a voltage drop judging circuit 30, a current fault judging circuit 31, and an AND circuit 32.

The voltage calculation circuit 28 is a power receiving / power supply system 1
When the instantaneous voltage value is input, it is converted to a voltage effective value and output to the voltage drop determination circuit 30. Further, when the current operation circuit 29 receives the instantaneous current value of the power receiving / power supply system 1, the current operation circuit 29 converts the instantaneous current value into an effective current value and outputs it to the current accident determination circuit 31. The voltage drop judging circuit 30 and the current fault judging circuit 31 each independently make a fault judgment, and when it is judged that a fault has occurred, outputs a fault occurrence determining signal to an AND circuit 32. Only when the judgment signal is input, the accident occurrence judgment signal is output to the control signal output circuit 27. When only one of the judgment signals is input, the accident occurrence judgment signal is not output to the control signal output circuit 27. In general, the voltage is liable to cause temporary level fluctuation due to noise or the like, and erroneous detection is likely to occur when the determination is made only with the voltage signal. , The accuracy of determination can be increased.

More specifically, when a serious short circuit accident occurs on the power receiving / power supply system 1 side, the commercial side load bus 6
, A rapid voltage drop and a rapid current increase occur simultaneously. Therefore, the output of the voltage calculation circuit 28 rapidly decreases and the output of the current calculation circuit 29 rapidly increases, so that both the voltage drop determination circuit 30 and the current fault determination circuit 31 output a fault occurrence determination signal. Therefore, the AND circuit 32 outputs an accident occurrence determination signal to the control signal output circuit 27,
Thereby, the semiconductor switch 3 is cut off at high speed.

When the power receiving / power supply system 1 is turned on, the large rush current flows in a short time, but the voltage does not decrease so much. Therefore, only the current fault determination circuit 31 outputs a fault occurrence determination signal to the AND circuit 32, so that the first fault determination circuit J1 outputs the fault occurrence determination signal to the control signal output circuit 2
7 is not output. FIG. 4 is a diagram in which a current limiting reactor 33 is added to the linkage configuration diagram of FIG.
In order to buffer the influence of the accident on the power receiving / power supply system 1 side, such a configuration that the current limiting reactor 33 is connected to the power receiving / power supply system 2 side is often adopted. In the case where a less serious accident occurs in such a configuration, even if a voltage drop of the commercial load bus 6 to some extent occurs temporarily, the current flowing through the semiconductor switch 3 varies due to the current limiting reactor 33. Since it becomes smaller, the current calculation circuit 29 does not output the accident occurrence determination signal to the AND circuit 32. Therefore, also in this case, the first accident judging circuit J1 does not output an accident occurrence judging signal to the control signal output circuit 27. Note that FIG.
Is configured such that the accident determination numerical conversion circuit 26 inputs two kinds of state quantities of voltage and current and converts them into numerical values suitable for accident judgment. May be configured to input the state quantities and convert them into numerical values suitable for accident determination.

FIG. 5 is a diagram showing CT1 for the semiconductor switch 3.
It is explanatory drawing which showed the attachment position of 7 and PT18. As shown in this figure, CT17 and PT18 are attached to the power receiving / power supply system 1 side (also in the conventional FIG. 15, it is shown that CT17 and PT18 are attached to the commercial load bus 6 side). However, this is an example in which the power supply is attached to the commercial load bus 6 by accident, and the power supply is sometimes attached to the generator bus 10.)

The CT17 and PT18 are connected to the commercial load bus 6
The advantage obtained by attaching to the side is that the installation position is close to the commercial system 4, so that the influence of the accident of the commercial system 4 can be detected more remarkably than the case where it is attached to the generator bus 10 side. Because. For example, as shown in FIG. 4, in a system configuration in which a current limiting reactor 33 is disposed between the semiconductor switch 3 and the power receiving / power supply system 2, even if an accident occurs on the commercial Since the influence is mitigated by the current limiting reactor 33, if the CT 17 and the PT 18 are mounted on the generator bus 10 side, an accident may not be detected or the detection timing may be delayed. Therefore, in each of the above embodiments, it is preferable to attach the CT 17 and the PT 18 to the commercial load bus 6 on the power receiving / power supply system 1 side.

FIG. 6 is a block diagram showing a specific configuration of the current calculation circuit 29 in the accident detection circuit 19C of the third embodiment shown in FIG. The current calculation circuit 29 includes absolute value conversion circuits 34U to 34W and a maximum value selection circuit (High V
alue Gate) 35. Each absolute value conversion circuit 34U
.About.34W receives U, V, and W phase currents, converts them into absolute values, and outputs the absolute values to the maximum value selection circuit 35. The maximum value selection circuit 35 selects the maximum value of the absolute values of the input phase currents and outputs the maximum value to the fault determination circuits J1 to JN.

FIG. 7 is a block diagram showing a configuration of an accident detection circuit 19D which is a main part of the fourth embodiment. FIG. 7 is different from FIG. 1 in that first to N-th accident determination circuits J1 to J1.
The point is that confirmation time limit circuits (on delay circuits) D1 to DN are added between JN and the control signal output circuit 27.
By adding such confirmation time limit circuits D1 to DN, it is possible to effectively prevent erroneous determination of occurrence of an accident.

For example, when the first accident judging circuit J1 judges that an accident has occurred, it outputs an accident occurrence judging signal to the confirmation timing circuit D1. It is monitored whether or not to continue, and after confirming that it has continued for a predetermined time, this accident occurrence determination signal is sent to the control signal output circuit 27 only after it is confirmed. Therefore, even if the first accident determination circuit J1 determines that there is an accident even though no accident has actually occurred, since the noise is superimposed on the voltage or current detection signal input from the system, Since the output of the accident occurrence determination signal is interrupted in a short time, the confirmation timed circuit D1 does not output the accident occurrence determination signal to the control signal output circuit 27. Therefore, the semiconductor switch 3 is prevented from being shut off due to an erroneous determination. The length of the above-mentioned predetermined time during which the confirmation time circuits D1 to DN confirm the continuation of the input of the accident occurrence determination signal is set within a range that does not affect the shut-off operation of the semiconductor switch 3.

FIG. 8 is a block diagram showing a configuration of an accident detection circuit 19E which is a main part of the fifth embodiment. FIG. 8 differs from FIG. 1 in that the accident determination numerical value conversion circuit 26 and the second
Filter circuits 36A and 36
B is connected.

The signal output from the accident determination numerical conversion circuit 26 often includes the influence of harmonics and noise superimposed on the system voltage and current. Is constituted by a microcomputer, a ripple component due to sampling is included, which may cause an erroneous determination. Therefore, in this embodiment, by adding the filter circuits 36A and 36B, it is possible to remove a component that may cause an erroneous determination.

As the filter circuits 36A and 36B, a low-pass filter for removing unnecessary high-frequency components or vibration components contained in the signal from the accident determination numerical conversion circuit 26 is used. Other filter circuits may be used. In this embodiment, the filter circuits 36A and 36B are connected to only the second accident determination circuit J2. However, connecting the filter circuits means that the processing speed is reduced. For this reason, a configuration is employed in which the first accident determination circuit J1 which requires high-speed determination processing is not intentionally connected. On the other hand, the fault judgment circuit of a lower level than the second fault judgment circuit J2 has a low judgment level and a long judgment time, so that the necessity of connecting a filter circuit is not so high.

FIG. 9 is a block diagram showing a configuration of an accident detection circuit 19F which is a main part of the sixth embodiment. FIG. 9 differs from FIG. 3 in that a signal holding circuit (off-delay circuit) 37 is connected to the output side of the current fault determination circuit 31 in the first fault determination circuit J1. This signal holding circuit 37
The reason for providing is described below.

In a cooperative system provided with a current limiting reactor 33 as shown in FIG. 4, when a short circuit accident occurs on the power receiving / power supply system 1 side, the DC current component of the current limiting reactor 33 is added to the current of each phase. Since (a DC current component of the reactor generated to compensate for the change in magnetic flux) is superimposed, the current waveform input to the current calculation circuit 29 is greatly shifted up and down as shown in FIG. Things appear. In the example of FIG. 10A, the U-phase and the W-phase are largely shifted up and down around the V-phase. Such a shift phenomenon generally appears remarkably in a system in which a semiconductor switch and a current limiting reactor are combined. The current operation circuit 29 includes the absolute value conversion circuits 34U to 34W and the maximum value selection circuit 35 as described above with reference to FIG. 6, but the maximum value selection circuit 35 outputs the signal due to the above-described shift phenomenon. The waveform is as shown in FIG. 10B, and has a very deep valley portion. And
Since the valley portion is lower than the threshold value of the accident judgment, as shown in the figure, the judgment of the presence of an accident and the judgment of the absence of an accident are repeated alternately, and if the accident judgment time is long, the accident actually occurs. However, there is a risk that an accident-free determination may be made despite the fact. Therefore, by providing the signal holding circuit 37, the signal level at the time of determining the presence of an accident is held for a predetermined time (about one cycle in the commercial frequency) after the determination of the presence of the accident, so that the presence of the accident is determined. The accident-free determination and the accident-free determination are not repeated alternately.

By providing the signal holding circuit 37 as described above, the influence of the saturation phenomenon of the current transformer CT17 can be avoided. That is, if the DC component of the current limiting reactor 33 is continuously superimposed on the passing current of the current limiting reactor 33 due to a short circuit accident on the power receiving / power supply system 1 side,
Since the CT 17 that detects the passing current is saturated, the detected value is smaller than the actual passing current value.
Therefore, when the accident determination time is long, even if an overcurrent actually flows, the overcurrent cannot be detected because the signal level inputted to the current calculation circuit 29 and the current accident determination circuit 31 becomes small. There is a fear. However, for the first waveform when the overcurrent is first detected, C
It must have been detected when T17 was not yet saturated. Therefore, by providing the signal holding circuit 37 and holding the level of the first waveform for a predetermined time, the CT 17
Can be prevented from being affected by the saturation.

FIG. 11 is a block diagram showing a configuration of an accident detection circuit 19G which is a main part of the seventh embodiment. FIG.
1 differs from FIG. 1 in that an external interface circuit 38 for inputting an accident occurrence detection signal 39 from an external device and outputting an accident occurrence signal to the control signal output circuit 27 is added.

Although not shown in FIGS. 13 and 4, actually, as shown in FIG. 12, the circuit breaker 4 is connected between the linking transformer 5 of the power receiving / power supply system 1 and the commercial system 4.
0 is provided. If the circuit breaker 40 is cut off by some kind of protection operation, the general load 7 cannot receive power supply from the commercial system 4, and instead receives power supply from the private power generator 8 on the power receiving / power supply system 2 side. Will be. However, in this case, the private generator 8 may be overloaded, and the power supply to the private load 11 which is an important load may be reduced. Therefore, in order to protect the self-generated load 11, when the circuit breaker 40 is turned off, the semiconductor switch 3 also needs to be turned off at the same time, but the voltage of the commercial load bus 6 and the generator bus 10 causes a short circuit accident. The semiconductor switch control device 15 cannot recognize that the circuit breaker 40 has been cut off, since it does not decrease as in the case of time.

Therefore, when the circuit breaker 40 performs the breaking operation, the operation signal is taken in as the accident occurrence detection signal 39 by the external interface circuit 38, and the semiconductor switch 3 is immediately turned on without waiting for the result of the accident judgment. Is cut off. In this embodiment, the case where the external device is the circuit breaker 40 is described. However, the present invention is not limited to the circuit breaker 40, and may be, for example, an operation device manually operated by an operator or the like.

[0067]

As described above, according to the present invention, the accident judging numerical conversion circuit inputs the state quantity from the first or second power receiving / power supply system and uses it for judging the presence or absence of an accident. Configuration in which the accident judgment circuit outputs judgment results based on different judgment levels, and the control signal output circuit outputs a control signal to the semiconductor switch based on input of judgment results from a plurality of accident judgment circuits. Therefore, it is possible to increase the accuracy of the accident detection and prevent the malfunction as much as possible while ensuring the high speed of the interruption operation at the time of the occurrence of the true accident.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an accident detection circuit 19A, which is a main part of a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an accident detection circuit 19B which is a main part of a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an accident detection circuit 19C which is a main part of a third embodiment of the present invention.

FIG. 4 is an application example of the third embodiment, and FIG.
FIG. 9 is a diagram illustrating a cooperative configuration of two power receiving / power supply systems in which a current limiting reactor 33 is added to the configuration of FIG.

FIG. 5 is an application example of the third embodiment, and is an explanatory diagram showing attachment positions of CT17 and PT18 with respect to a semiconductor switch 3.

FIG. 6 is a block diagram showing a specific configuration of a current calculation circuit 29 in an accident detection circuit 19C according to the third embodiment.

FIG. 7 is a block diagram showing a configuration of an accident detection circuit 19D which is a main part of a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an accident detection circuit 19E which is a main part of a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of an accident detection circuit 19F which is a main part of a sixth embodiment of the present invention.

10 is a waveform chart for explaining the operation of the signal holding circuit 37 in FIG.

FIG. 11 is a block diagram showing a configuration of an accident detection circuit 19G which is a main part of a seventh embodiment of the present invention.

FIG. 12 illustrates two power receiving / receiving devices to which the seventh embodiment is applied.
FIG. 3 is a diagram illustrating a cooperative configuration of a power supply system.

FIG. 13 is a diagram illustrating a cooperative configuration of two power receiving / power supply systems.

FIG. 14 is a configuration diagram of a semiconductor switch 3 in FIG. 13;

FIG. 15 shows the semiconductor switch 3 shown in FIG. 13 or FIG.
FIG. 2 is a block diagram showing a configuration of a semiconductor switch control device 15 that performs control on the switch.

16 is a semiconductor switch control device 15 shown in FIG.
FIG. 7 is a waveform chart showing the correspondence between signals ((a) to (e)), voltage (f), and current (g) for one phase.

17 is a semiconductor switch control device 15 shown in FIG.
FIG. 9 is a waveform chart showing the correspondence between signals ((a) to (e)), voltage (f) and current (g) for the three phases.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power receiving / power supply system 2 Power receiving / power supply system 3 Semiconductor switch 4 Commercial system 5 Linkage transformer 6 Commercial load bus 7 General load 8 Private generator 9 Transformer 10 Generator bus 11 Self-generated load 12 U / X thyristor arm 13 V / Y thyristor arm 14 W / Z thyristor arm 15 semiconductor switch control device 16 gate signal 17 CT 18 PT 19, 19A to 19G accident detection circuit 20 cutoff command 21 open / close determining means 22 open command 23 close command 24 interlock circuit 25 gate Control circuit 26 Numerical conversion circuit for accident judgment J1 to JN First to Nth accident judgment circuits 27 Control signal output circuit 28 Voltage operation circuit 29 Current operation circuit 30 Voltage drop judgment circuit 31 Current accident judgment circuit 32 AND circuit 33 Current limiting Reactor 34U-34W Absolute value conversion circuit 3 Maximum value selection circuits 36A, 36B filter circuit 37 the signal holding circuit 38 external interface circuit 39 accident detection signal 40 breaker

Claims (12)

[Claims] 1. A first power receiving / power supply system and a second power receiving / power supply system.
A semiconductor switch, which is arranged on a bus connecting to the power supply system and switches a connection state between the two systems, controls the switching operation based on a detection result of an accident occurring in one of these two systems. In the semiconductor switch control device, an accident determination numerical value conversion circuit that inputs a state quantity from the first or second power receiving / power supply system and converts the state amount into a numerical value suitable for determining whether or not an accident has occurred; A plurality of accident determination circuits for inputting numerical values from the numerical value conversion circuit and outputting the determination results based on different determination levels, and controlling the semiconductor switch based on the input of the determination results from the plurality of accident determination circuits. And a control signal output circuit that outputs a signal. 2. The first power receiving / power supply system has a general load that is always supplied with electric power from a commercial system, and the second power receiving / power supply system is always supplied with electric power from a private power generator. The semiconductor switch control device according to claim 1, wherein the semiconductor switch control device receives a self-generated load as an important load. 3. The method according to claim 2, wherein each of the plurality of accident determination circuits has a shorter time to output a determination result as the determination level approaches a serious accident occurrence level. 3. The semiconductor switch control device according to 1 or 2. 4. The semiconductor switch control device according to claim 2, wherein the state quantity input to the accident determination numerical conversion circuit is a bus voltage on the first power receiving / power supply system side. 5. A first fault judgment circuit for outputting a judgment result at a high speed based on a first voltage judgment level, and a second fault judgment circuit set at a higher level than the first voltage judgment level. 4. The semiconductor switch control device according to claim 3, further comprising: a second fault determination circuit that outputs a determination result at a low speed based on the voltage determination level. 6. The state quantity input to the accident determination numerical conversion circuit is a first and a second type of state quantity, and each of the plurality of accident determination circuits is based on the first state quantity. First determining means for outputting a first determination result, second determining means for outputting a second determination result based on the second state quantity, and a logical product of the first and second determination results 6. A semiconductor switch control device according to claim 1, further comprising: an element determination output unit configured to output the determination result to the control signal output circuit. 7. The system according to claim 1, wherein the first state quantity is an instantaneous voltage value at a predetermined point in the system, and the second state quantity is an instantaneous current value at a predetermined point in the system. Outputs an accident occurrence level signal as the first determination result when the instantaneous voltage value becomes equal to or less than the set value, and the second determination means determines whether the instantaneous current value exceeds the set value. Outputs an accident occurrence level signal as the second judgment result, and the element judgment output means outputs an accident occurrence judgment signal to the control signal output circuit based on a logical product of these two accident occurrence level signals. The semiconductor switch control device according to claim 6, wherein: 8. The power received by the first and second power receiving / power supply systems is AC power, and the accident determination numerical conversion circuit inputs a current instantaneous value of each phase as the state quantity. A current calculation circuit that outputs these to the plurality of fault determination circuits as a value suitable for determining the presence or absence of the fault, converting the maximum value of these absolute values into a value suitable for determining the presence or absence of the fault. The semiconductor switch control device according to claim 1, wherein: 9. The control signal output circuit according to claim 1, wherein each of the plurality of accident decision circuits outputs a decision result indicating that an accident has occurred continuously for a predetermined time to each output side of the plurality of accident decision circuits. The semiconductor switch control device according to any one of claims 1 to 8, wherein a confirmation time limit circuit that permits output of the semiconductor switch is connected. 10. The semiconductor switch control according to claim 1, wherein a filter circuit for removing a high-frequency component is connected to each input side of said plurality of fault judgment circuits. apparatus. 11. A signal holding circuit for continuously outputting the accident occurrence level signal to the element determination output means for a predetermined time is connected to an output side of the second determination means. 13. The semiconductor switch control device according to claim 1. 12. An external interface circuit for outputting an accident occurrence detection signal to the control signal output circuit based on an input signal from a predetermined external device, wherein the control signal output circuit receives the accident occurrence detection signal. The semiconductor switch control device according to any one of claims 1 to 11, wherein a control signal for the semiconductor switch is output immediately.