JP7620581B2 - Plant monitoring system and plant monitoring device - Google Patents

Description

This disclosure relates to a plant monitoring system and a plant monitoring device.

Normally, the operating status of electrical equipment within a plant, such as circuits and loads, is monitored by managers and operators (hereinafter referred to as "operators, etc.") using instruments installed on monitoring panels and on-site. Any abnormalities are detected by protective relays installed on each circuit, and an alarm is issued. Operators, etc. become aware of the occurrence of an abnormality through the alarm. In such cases, operators, etc., only become aware of the abnormality after checking the alarm, and so they tend to be slow to take action, such as replacing or repairing the equipment in question. This situation leads to a decrease in the operating rate of the power plant.

To take proactive measures, it is necessary to regularly monitor electrical measurement signals through periodic testing and pay close attention to changes in the state of electrical circuits. Currently, it is difficult to detect abnormalities early from measurement data, and test personnel are required to make judgments based on judgment values and past experience.

On the other hand, future power grids are expected to be decentralized, and if many small-scale power plants are installed, implementing the above-mentioned monitoring would pose an issue, as it would require a huge amount of human resources. In response to this issue, a system has already been proposed for remote centralized monitoring when multiple power plants are installed.

Patent Document 1 discloses that sensors and other measuring instruments are attached to equipment at hydroelectric power plants, including water level gauges, inlet valves, water turbines, servo motors, generators, circuit breakers, transformers, and power transmission equipment, and that the measuring instruments measure physical quantities such as pressure and temperature, and electrical quantities such as voltage, current, and frequency, of the equipment to which they are attached, that each measuring instrument outputs its measurement value to a monitoring and control system, that the monitoring and control device of the monitoring and control system is connected to a monitoring and control terminal device via a network, that the monitoring and control terminal device is located in a remote location away from the hydroelectric power plant, and that although multiple monitoring and control terminal devices can simultaneously monitor multiple hydroelectric power plants, control over the equipment at the hydroelectric power plant is given to one monitoring and control terminal device, thereby enabling those involved in the hydroelectric power plant to control the operation of the equipment at the hydroelectric power plant conveniently and without confusion.

JP 2021-103447 A

In Patent Document 1, hydroelectric power plants are the subject of monitoring, but this is not the only subject. Power generation facilities such as wind power plants and solar power plants are becoming relatively small and are being distributed.

Power plants are equipped with protective relays as electrical equipment. Protective relays are capable of detecting abnormal events such as overcurrents, ground faults, short circuits, low voltages, and overvoltages. Specifically, protective relays detect extreme changes in electrical behavior caused by abnormalities in the circuit, such as an increase in zero-phase current or zero-phase voltage in the case of a ground fault, as an abnormality.

When such extreme changes in electrical behavior occur, it is often the case that some sort of fault has already occurred in the circuit. In this case, the plant must be shut down to verify the fault and replace the equipment. As a result, the plant may be shut down for an extended period of time, which could result in a drop in availability. To avoid such events, it is necessary to regularly monitor the status of each load, recognize abnormalities in the loads early, ensure a period of time to prepare for abnormalities, make sufficient preparations in advance, and have a system in place to quickly return to normal operating conditions if an abnormality occurs.

In recent years, research into distributed power sources has accelerated, and it is expected that many small-scale power plants will be installed in future power grids. In that case, human resources to monitor the above-mentioned abnormalities will be required for each plant, and there is a possibility that there will be a significant shortage of human resources. In order to avoid this, a system that automatically monitors abnormalities is desirable.

The purpose of this disclosure is to provide a function for automatic remote monitoring of abnormalities in electrical circuits, thereby reducing the burden on operators and improving the reliability of power systems through early detection of failures.

The plant monitoring system disclosed herein is a system for monitoring plant equipment including at least one of a load circuit, a main circuit, and a circuit breaker installed in a plurality of plants, and is equipped with a monitoring device having a signal receiving unit and a judgment unit, an electric quantity measuring instrument is installed in the load circuit and the main circuit, and an electric quantity measuring instrument or an operation signal detector is installed in the circuit breaker, the signal receiving unit receives at least one of an electric measurement signal including a current measured by the electric quantity measuring instrument and an operation signal of the circuit breaker detected by the operation signal detector, and the judgment unit compares at least one of the electric measurement signal and the operation signal between two or more plants among the plurality of plants, and judges that an abnormality exists in the load circuit, the main circuit, or the circuit breaker if the difference in the value of the signal is equal to or greater than a predetermined value.

This disclosure provides a function for automatic remote monitoring of abnormalities in electrical circuits, reducing the burden on operators and other personnel, while improving the reliability of the power system through early detection of failures.

FIG. 2 is a schematic configuration diagram showing a connection state of a plant according to an embodiment. FIG. 2 is a schematic diagram showing a load state and a plant mode of the plant. FIG. 1 is a schematic diagram showing an example of a configuration for comparing electrical measurement signals using a virtual plant created by simulation in a plant monitoring device. FIG. 13 is a schematic diagram showing an example of a configuration for comparing electrical measurement signals when plants connected to different systems are in the same plant mode. 1 is a schematic configuration diagram showing a plant monitoring device according to an embodiment; FIG. 2 is a flow diagram showing an abnormality determination method by the plant monitoring device of the embodiment.

The plant monitoring system according to the present disclosure includes a plurality of plants and a plant monitoring device. The plant monitoring system may further include one or more systems.

The plant monitoring system estimates the plant mode from the electrical quantities measured by electrical meters installed in the load circuits (hereinafter also referred to as "loads") and main circuits (hereinafter also referred to as "main circuits") within the plant, and from signals related to the open/closed state of the electrical circuits, and compares the current values of each circuit of the plant being evaluated with the current values of each circuit of other plants in the same plant mode, and if a difference between them that exceeds a certain threshold is found, it determines that an abnormality has occurred.

In this specification, a plant refers to equipment such as a power plant. The plant is equipped with plant equipment including at least one of a load, a main circuit, and a circuit breaker. The plant equipment is configured to be monitored by a plant monitoring device. In addition, a similar plant mode includes not only the same plant mode, but also plant modes that are nearly the same, i.e., have similar states.

The plant monitoring device (also simply referred to as "monitoring device") has a signal receiving unit (input unit) and a judgment unit (detection and judgment unit). Of the plant equipment, electric quantity measuring instruments are installed on the loads and main electric circuits. In addition, electric quantity measuring instruments or operation signal detectors are installed on the circuit breakers. The signal receiving unit of the monitoring device receives at least one of an electric measurement signal including a current value measured by the electric quantity measuring instrument, and an operation signal of the circuit breaker detected by the operation signal detector.

Embodiments of the present disclosure will be described below with reference to the drawings. Note that in each drawing, the same components are given the same reference numerals, and duplicate descriptions will be omitted as appropriate.

Figure 1 is a schematic diagram showing the connection state of a plant in an embodiment.

In this diagram, a first plant 104, a second plant 105, and a third plant 106 are connected to a first system 101. A fourth plant 107 is connected to a second system 102. The first system 101 and the second system 102 are connected by a connection bus 103. In this specification, the term "main electrical circuits" may include not only the main wiring within a plant, but also the connecting wiring and connection bus between the systems and the plants.

The first plant 104, the second plant 105, the third plant 106, and the fourth plant 107 are connected to the plant monitoring device 100. The plant monitoring device 100 acquires electrical measurement signals from each plant, performs predetermined calculation processing, determines whether or not there is an abnormality, and notifies operators, etc., as necessary.

Here, the first system 101 and the second system 102 are separate systems and are not identical in electrical quality. Therefore, even if the electrical equipment installed in each of the first plant 104, the second plant 105, the third plant 106, and the fourth plant 107 has the same specifications, the electrical measurement signals of the first plant 104, the second plant 105, and the third plant 106 and the electrical measurement signal in the fourth plant 107 are signals with different characteristics due to different system conditions.

Figure 2 is a schematic diagram showing the load state and plant mode of the plant.

In the example shown in this figure, the loads installed in each plant are three pumps. When all three pumps in one plant are operating (when all are ON), this is considered to be the first mode. When all three pumps are stopped (when all are OFF), this is considered to be the second mode. The first mode and second mode are examples of plant modes.

The plant monitoring device 100 (Figure 1) acquires signals from electrical quantity measuring instruments such as digital relays and ammeters installed in each load, as well as from circuit breaker on/off signals, to detect the operation or stop of the loads and estimate the plant mode.

When the plant monitoring device 100 detects the load state of the first plant 104, it estimates that the first mode is in progress since all loads are operating. When the plant monitoring device 100 detects the load state of the second plant 105, it estimates that the second mode is in progress since all loads are stopped. When the plant monitoring device 100 detects the load state of the third plant 106, it estimates that the first mode is in progress since all loads are operating. In this case, the magnitude of the current values of the first plant 104 and the third plant 106, which are both estimated to be in the first mode, are compared, and if the difference is equal to or greater than a certain value, it is determined that an abnormality has occurred.

Note that in this diagram, the load is a pump, but other loads related to this disclosure include a motor, etc.

In FIG. 1, the first plant 104, second plant 105, and third plant 106 connected to the first system 101 differ in electrical specifications, such as the system voltage, from the fourth plant 107 connected to the second system. For this reason, it is difficult to simply compare electrical measurement signals in plants with different systems. In addition, when there is no comparison target, for example, when there is no other plant in the connected system, such as the fourth plant 107, or when there is no plant with the same plant mode even if the system is the same, such as the second plant 105 in FIG. 2, it is difficult to compare electrical measurement signals.

Therefore, in such cases, a virtual plant is created through simulation and compared with the actual plant to determine whether there is an abnormality.

Figure 3 is a schematic diagram showing an example of a configuration for comparing electrical measurement signals using a virtual plant created by simulation in a plant monitoring device.

In this diagram, the plant monitoring device 100 performs an analysis (simulation) simulating the same plant mode (here, the third mode) as the fourth plant 107 to be evaluated, and judges whether there is an abnormality by comparing the measurement signal of the fourth plant 107 with the current value obtained by simulating the third mode of the fourth plant 107.

Figure 4 is a schematic diagram showing an example of a configuration for comparing electrical measurement signals when plants connected to different systems are in the same plant mode.

In this diagram, as in FIG. 1, the first system 101 having the first plant 104, the second plant 105, and the third plant 106 and the second system 102 having the fourth plant 107 have different power supply specifications and conditions, and also different voltage values. Assuming this as a prerequisite, even if the first plant 104, the third plant 106, and the fourth plant 107 are operating in the same plant mode (first mode), a change in voltage will cause a change in current due to the load characteristics (constant power characteristics and constant impedance characteristics). For this reason, a simple comparison of current values will result in a state in which differences always occur, making it difficult to determine an abnormality.

Here, the voltage values of the first system 101 and the second system 102 are input to the plant monitoring device 100 (Figure 1). Then, in the plant monitoring device 100, the system voltage value of the plant to be referenced of the two plants is replaced with the voltage value of the reference plant 407, and the load current value is estimated by simulation. By using the estimated current value, it becomes possible to compare the reference plant 407 even if the plant is a different system from the plant it references. In this case, the system may be an external power supply system or an on-site power supply system within the plant.

As a simple example, consider a case where the load is a resistive load with constant impedance characteristics under the conditions that the bus voltage of the first plant 104 is 6.90 kV and the bus voltage of the fourth plant 107 is 6.85 kV. The bus voltage of the fourth plant 107 is actually 6.85 kV, but the current value when it is set to 6.90 kV is estimated through simulation.

If the impedance characteristics are constant, the load currents increase at a ratio of 6.90 kV/6.85 kV. In this way, by aligning the voltage conditions between the first plant 104 and the fourth plant 107, it becomes possible to compare the current values.

Note that here, to simplify the explanation, we have focused only on voltage, but the same applies when conditions such as frequency change. Compared to Figure 3, this has the advantage that it is not necessary to build an entire system model, and only the conversion of current values is required.

When there are multiple plant modes to distinguish, it is possible to distinguish various operating modes based on the load energization sequence and the magnitude of the load current. For example, in a power generation plant, a startup sequence for supplying emergency power for emergency operations is determined for each event, so it is possible to assume the plant mode based on the load energization sequence.

In this example, we have mainly explained the comparison of current values, but by processing the current values and comparing other measurement signals, more detailed comparisons and analyses are possible. For example, by decomposing the measured current values into symmetrical components using the symmetric coordinate method, it becomes possible to monitor earth faults and unbalance rates, which cannot be determined by the magnitude of the current alone. By combining measurements such as voltage values and frequency, it becomes possible to monitor circuit losses, motor torque and slippage, etc.

The configuration and processing flow of the plant monitoring device of this embodiment are described below.

Figure 5 is a schematic diagram showing a plant monitoring device according to an embodiment.

In this diagram, the plant monitoring device 100 includes an input unit 151, a detection/determination unit 152, an analysis unit 153, an output unit 154, and a memory unit 160.

The input unit 151 receives electrical measurement signals from each plant. The detection and determination unit 152 performs a predetermined calculation process on the received electrical measurement signals to determine whether or not there is an abnormality. The analysis unit 153 performs the above simulation. The output unit 154 transmits notifications regarding the results of the determination and simulation to operators, etc. The memory unit 160 transmits necessary data to the detection and determination unit 152 and the analysis unit 153, and receives data that needs to be stored from the detection and determination unit 152 and the analysis unit 153.

Figure 6 is a flow diagram showing an anomaly determination method using a plant monitoring device according to an embodiment.

As shown in this figure, in the plant monitoring device, the detection and judgment unit 152 detects the load state of the plant from the data received by the input unit 151 (step S610). Then, the detection and judgment unit 152 estimates the plant mode from the load state of the plant (step S620). Next, the detection and judgment unit 152 compares plants of the same mode (step S630). Then, the detection and judgment unit 152 judges whether there is an abnormality in the plant (step S640). If there is an abnormality, the output unit 154 notifies the operator or the like of the abnormality (step S650). If there is no abnormality, the process returns to step S610.

Below, we will summarize preferred embodiments of the plant monitoring system and plant monitoring device according to the present disclosure.

The determination unit estimates the plant mode from at least one of the electrical measurement signal and the operation signal, and compares two or more plants that are in the same plant mode among the multiple plants.

The determination unit estimates the plant mode of the actual plant from at least one of the measured electrical measurement signals and the detected operation signals. The analysis unit creates a virtual plant by simulating the plant mode. The determination unit then compares at least one of the electrical measurement signals and the operation signals between the actual plant and the virtual plant, and if the difference in the signal values is equal to or greater than a predetermined value, determines that there is an abnormality in the load circuit, main circuit, or breaker.

The determination unit estimates the plant mode based on at least one signal of the load circuit energization sequence and the magnitude of the current in the load circuit.

The judgment unit makes the comparison by matching the voltage or frequency conditions between two or more plants.

The load circuit has an electric motor, and the judgment unit compares the torque or slip of the electric motor between two or more plants based on the current and voltage values, and judges that the load circuit is normal if the difference in the torque or slip value is less than a predetermined value.

The power generation facilities that are subject to monitoring by the plant monitoring system according to the present disclosure include hydroelectric power plants, wind power generation facilities, solar power generation facilities, geothermal power plants, nuclear power plants, etc.

100: plant monitoring device, 101: first system, 102: second system, 103: connecting bus, 104: first plant, 105: second plant, 106: third plant, 107: fourth plant, 151: input unit, 152: detection and judgment unit, 153: analysis unit, 154: output unit, 160: memory unit, 407: comparison target plant.

Claims (6)

A system for monitoring plant equipment including at least one of a load circuit, a main circuit, and a breaker installed in a plurality of plants, comprising:
A monitoring device having a signal receiving unit and a determination unit,
An electric quantity measuring instrument is installed in the load circuit and the main circuit,
The circuit breaker is provided with an electric quantity measuring device or an operation signal detector,
The signal receiving unit receives at least one of an electrical measurement signal including a current measured by the electrical quantity measuring device and an operation signal of the circuit breaker detected by the operation signal detector,
the determination unit compares at least one of the electrical measurement signal and the operation signal between two or more plants among the plurality of plants, and when a difference between values of the signals is equal to or greater than a predetermined value , determines that an abnormality exists in the load circuit, the main circuit, or the breaker;
The determination unit estimates a plant mode from at least one of the electrical measurement signal and the operation signal, and performs the comparison between two or more plants in the same plant mode among the multiple plants . A system for monitoring plant equipment including at least one of a load circuit, a main circuit, and a breaker installed in a plant, comprising:
A monitoring device having a signal receiving unit, a determining unit, and an analyzing unit,
An electric quantity measuring instrument is installed in the load circuit and the main circuit,
The circuit breaker is provided with an electric quantity measuring device or an operation signal detector,
The signal receiving unit receives at least one of an electrical measurement signal including a current measured by the electrical quantity measuring device and an operation signal of the circuit breaker detected by the operation signal detector,
The determination unit estimates a plant mode of an actual plant from at least one of the measured electrical measurement signal and the detected operation signal,
the analysis unit creates a virtual plant by simulating the plant mode;
The judgment unit compares at least one of the electrical measurement signal and the operation signal between the actual plant and the virtual plant, and if a difference in the value of the signal is equal to or greater than a predetermined value, judges that an abnormality exists in the load circuit, the main circuit, or the breaker. 3. The plant monitoring system according to claim 2 , wherein the determining unit estimates the plant mode based on at least one signal of a current supply sequence of the load circuits and a magnitude of a current in the load circuits. The plant monitoring system of claim 1, wherein the determination unit performs the comparison by making the voltage or frequency conditions uniform between the two or more plants. The load circuit includes an electric motor.
5. The plant monitoring system according to claim 4, wherein the determination unit compares the torque or slip of the motor between the two or more plants from the current and voltage values, and determines that the load circuit is normal if a difference in the torque or slip value is less than a predetermined value. An apparatus for monitoring plant equipment including at least one of a load circuit, a main circuit, and a breaker installed in a plurality of plants, comprising:
A signal receiving unit;
A determination unit,
the signal receiving unit receives at least one of an electrical measurement signal including a current value measured by an electrical quantity measuring device installed in the load circuit and the main circuit, and an operation signal of the circuit breaker detected by an operation signal detector installed in the circuit breaker;
the determination unit compares at least one of the electrical measurement signal and the operation signal between two or more plants among the plurality of plants, and when a difference between values of the signals is equal to or greater than a predetermined value , determines that an abnormality exists in the load circuit, the main circuit, or the breaker;
The determination unit estimates a plant mode from at least one of the electrical measurement signal and the operation signal, and performs the comparison between two or more plants in the same plant mode among the multiple plants .

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