System and method for determining the position of a movable arm of a high voltage disconnect switch

Abstract

The present disclosure relates to a system for determining a position of a movable arm of a high voltage disconnect switch. The system includes a high voltage disconnect switch and a ToF sensor, the high voltage disconnect switch including a movable arm for opening and closing the high voltage disconnect switch, the ToF sensor configured to determine a distance value indicative of a distance from the high voltage disconnect switch to the movable arm. The system further includes a controller configured to determine whether the high voltage disconnect switch is in an open state or a closed state based on the distance value. Additionally, a method for determining a position of a movable arm of a high voltage disconnect switch is provided.

Description

Technical Field

[0001] The present disclosure discloses a system and method for determining the position of a movable arm of a high-voltage disconnecting switch.

[0002] Smart substations are building methods to improve operational safety and reduce outage time. Digitalization of asset status by smart sensors enables rapid error location and preventive maintenance. The Breaking-closing disconnecting switch (BCDS) is one of the most important components in today's substation equipment. The Breaking-closing disconnecting switch (BCDS) is also referred to as a high-voltage disconnecting switch in this specification. Such components have moving parts. Therefore, operating the BCDS can, of course, cause failure modes such as the following. That is, · The switch is mechanically blocked in a position that is neither "open" nor "closed". · Due to the relative positions of the male and female contacts, a complete "closed" state cannot be obtained (finger pressing pressure is low), resulting in a temperature rise of each contact and a possible low conduction current.

[0003] The IEC62271-102 standard describes an overall mandatory test for disconnecting the switch connection. According to the IEC, the device is expected to correctly indicate the position of the disconnect switch. Such a device is not specified in detail. According to Douillard et al., BCDS causes a major part of important events related to the safety of the electrical system (ESS) in substation facilities. For this, see S. Douillard et al., “Disconnectors reliability on the French grid and means to reduce the consequences of their failures on the electrical system”, Cigre 2018. The main problem that occurs is the loss of "open or closed" information. Such events limit topology changes, weaken the substation system, and require on-site intervention. Motivated by these facts, smart sensors for monitoring the state of the device have been developed. By using such sensors, insights into the health of the BCDS can be obtained through data logging and processing, and preventive measures can be initiated if necessary.

[0004] Currently, various methods are being considered to enable the monitoring of the switch state. Douillard et al. employ real-time monitoring of the operating torque of the circuit breaker. In this method, the movement of the switch can be compared with the minimum and maximum values. It has been reported that the operating torque value depends greatly on the ambient temperature. This needs to be corrected by an algorithm.

[0005] A good review of other monitoring techniques can be obtained from Bozhong et al., “Review on Breaking-closing Position Monitoring Method for Intelligent Disconnecting Switches”, IOP Conf. Ser.: Earth Environ. Sci. 223, 2018. The method being studied here is image recognition. The aim of this method is to extract features from the image region in order to derive the state of the BCDS. For this, see, for example, Wu et al., “An image recognition method of substation breakers state based on robot”, Power System Automation, Vol36, 2020 and Chen et al., Image recognition in online monitoring of power equipment, Int. J. o. Adv. Rob. Syst. 2020. The method can be carried out using a fixed camera or a moving camera for observing the switch. In addition to advantages such as high automation and scalability, this method has disadvantages such as being easily affected by weather conditions and being costly. Also, by using a camera for photography, this method is also easily affected by the magnetic field of the BCDS environment.

[0006] By Zhang et al., “Design and research on laser monitor device of intelligent high voltage disconnector position” Automation Application Vol 03, 2012 and Semedo et al., “Remote monitoring of High Voltage Disconnect Switches in Electrical Distribution Substations”, Int. Symp. On Ind. Electr. ISIE, 2014, an optical-based approach has been presented. In Zhang et al., a laser source and mirrors are used to determine whether the switch contacts are in the correct position. In Semedo et al., three subsystems are integrated into a single monitoring unit. Relative position sensing is performed using a single LED and 32 phototransistors. MEMS is used to enable vibration measurements during operation. A solar panel is used as the current source. The operating period of the monitoring unit depends on the data communication frequency. However, there is room for improvement regarding the spatial and / or temporal resolution of the measurements that enable preventive maintenance in each of the methods presented here. Furthermore, in the approach of Semedo et al., all of the subsystems used require the flow of current. It is unclear how to ensure the accurate calibration and stable operation of the electrically driven subsystems in the direct vicinity of a high magnetic field.

[0007] To address future challenges such as including renewable energy sources in the power grid despite their unpredictable production patterns and assisting the energy consumption peaks resulting from the integration of electromobility into the power grid, the achievement of grid stability is desired. Therefore, the digitization of substation equipment by smart sensors is desirable.

[0008] Such sensors should be able to handle the high electromagnetic fields in substation equipment. Optical technology enables the operation of such sensors based on an optical approach while avoiding interference with the electromagnetic fields in the environment. However, for example, an evaluation by a camera functions only when a clear view of the movable arm of the switch is obtained and may be subject to interference, for example, by fog, rain, or snow.

[0009] In view of the above, an object of the present disclosure is to provide a system and method for determining the position of a movable arm of a high-voltage disconnect switch that overcomes at least one of the above problems of the prior art and / or other related problems.

[0010] According to a first aspect, a system for determining the position of a movable arm of a high-voltage disconnect switch is provided. The system includes a high-voltage disconnect switch and a ToF (Time of Flight) sensor. The high-voltage disconnect switch includes a movable arm for opening and closing itself, and the ToF sensor is configured to determine a distance value indicating the distance from itself to the movable arm. The system further includes a control device configured to determine whether the high-voltage disconnect switch is in an open state or a closed state based on the distance value.

[0011] In the following description, unless otherwise indicated, the expression "arm" refers to the "movable arm", the expression "switch" refers to the "high-voltage disconnect switch", and the expression "sensor" refers to the "ToF sensor".

[0012] The movable arm can be a metal arm configured to open and close an electrical connection. In the open state, current cannot flow through the movable arm and thus the switch. In the closed state, current can flow through the movable arm and thus the switch. There may be an intermediate state that passes while the movable arm moves from the open state to the closed state or vice versa from the closed state to the open state between the open state and the closed state. In such an intermediate state, a secure connection / disconnection cannot be guaranteed.

[0013] The movable arm can perform a rotational motion. The rotational motion is that the movable arm moves within a plane (hereinafter referred to as the rotational motion plane). In particular, the axis of rotation of the said motion can be arranged to pass through the first end of the movable arm. In this case, the motion of the movable arm can be regarded as a pivoting motion. A first contact portion can be arranged at the second end of the movable arm, and this first contact portion is configured to shift the switch to the closed state by making electrical contact with the second contact portion of the switch. In the closed state, current can flow from the first end of the arm, through the arm and the contact portion of the arm, to the second contact portion (or in the reverse direction). In the open state, since the first contact portion and the second contact portion are physically separated (by air), current cannot flow.

[0014] The second contact portion of the switch may be fixed or may be arranged at the end of another movable arm of the switch. In the latter case, the switch may have two movable arms, and these arms move closer to each other when the switch closes and move away from each other when the switch opens. The two arms can move as a rotational motion. The rotational motions of both may occur in the same plane. The first contact portion and the second contact portion can be configured as a male contact portion and a female contact portion in which the female contact portion surrounds the male contact portion in the closed state.

[0015] The motion of the movable arm can be actuated by an actuator (such as an electric motor) that is electrically driven under the control of a control device (such as the control device described in this specification). The said system can be integrated into the substation equipment or can be configured to be integrated into the substation equipment.

[0016] In the present disclosure, according to a common definition, a high voltage can be defined as more than 1 kV for AC RMS voltage and more than 1.5 kV for DC voltage.

[0017] The distance value may be any value indicating the distance from the ToF sensor to the movable arm. For example, the distance value may directly indicate the distance (e.g., in m or mm), or may be a time value indicating the travel time of a laser signal that travels from the ToF sensor to the movable arm and back (e.g., in s or ns). Also, a time-dependent distance value may be provided by the ToF sensor and recorded by the control device (e.g., in the memory of the control device). The ToF sensor can operate in pulse mode, and a corresponding distance value is formed for each pulse. The distance value may be the distance value of a specific pixel of the image sensor of the ToF sensor, or may be the average value of a predetermined subset of pixels. When a pixelated image sensor is used in the ToF sensor, each pixel of the detector has a predetermined detection direction (and corresponding detection area) within the entire field of view provided by the ToF sensor. The distance value for each pixel indicates the distance along the detection direction.

[0018] The control device can include at least one processor and at least one memory. Instructions for operating the processor according to one or more of the methods described herein may be stored in the memory. The control device may include components implemented within hardware and / or within software. One or more components of the control device may be physically separated from each other. For example, one or more components of the control device may be arranged in the cloud. The control device is configured to determine whether the high-voltage disconnect switch is in an open state or a closed state based on the distance value. For example, the memory of the control device may include instructions for causing the processor to determine whether the high-voltage disconnect switch is in an open state or a closed state based on the distance value. In this regard, the control device can also be considered to include a "determinator" or "determination unit" that performs the task of determination.

[0019] Furthermore, the control device can be configured to determine the position of the movable arm. In other words, it is also possible to determine an intermediate state of the movable arm between the open state and the closed state. For example, it may be possible to determine the opening angle of the movable arm (for example, 0° can be assumed to indicate the closed state, and 90° can be assumed to indicate the open state).

[0020] The movable arm can be configured to rotate within the plane of rotation, and the ToF sensor can be arranged out of the plane and facing the plane such that at least a part of the movable arm is within the field of view of the ToF sensor during at least a part of the movement of the movable arm from the closed state to the open state.

[0021] For example, at least a part of the movable arm may be within the field of view of the sensor in the closed state, or in the open state, or in both the open and closed states. The sensor may be arranged on the floor surface and oriented upward toward the plane of movement of the movable arm. The field of view can be defined as the area within which the sensor can measure the distance. For example, if the sensor includes a two-dimensional pixelated image sensor, the field of view can be defined as the area within which the image sensor can measure the distance (by detecting the reflected laser pulses).

[0022] For example, the sensor can be arranged such that at least a part of the movable arm is located within the field of view of the sensor in the closed state. The sensor can be arranged such that the distance value determined in the closed state corresponds to a predetermined distance, and the distance value determined in the open state corresponds to a distance greater than the predetermined distance. For example, the control device can be configured to determine that the high-voltage cut-off switch is in the closed state when the determined distance value is less than or equal to a predetermined distance value, and to determine that the high-voltage cut-off switch is in the open state when the determined distance value is at least a predetermined amount greater than the predetermined value. For example, the predetermined distance value can be 2 m, and the control device can determine the open state when the sensor measures a distance value of at least 3 m (= 2 m + 1 m). The open state can also be determined when the distance cannot be measured by the sensor, that is, when the determined distance is at the maximum value predetermined by the sensor (for example, predetermined by the pulse length of the laser pulse used).

[0023] In an arrangement configuration where the sensor faces a plane, two or more pixels of the sensor can be evaluated. In this case, when a predetermined subset of pixels outputs a distance value less than or equal to a predetermined distance value, the control device can determine that the switch is in the closed state. Also, when another subset of pixels outputs a distance value less than or equal to a predetermined distance value, the control device can determine that the switch is in the safe position. Further, when none of the pixels outputs a distance value less than or equal to the predetermined distance value, the control device can determine that the switch is in the open position.

[0024] In some situations, the above arrangement configuration can be advantageous because it allows for a simple arrangement of the sensor (e.g., on the floor surface), and a clearly detectable change is formed in the distance signal when the arm moves out of the detection area of a specific pixel of the sensor. In other words, the gradient of the determined time-dependent distance value is large so that the time point when the movable arm passes through the detection area of a specific pixel can be accurately determined.

[0025] The movable arm can be configured to rotate within a rotational movement plane, and the ToF sensor can be arranged within the plane and oriented to face the movable arm such that at least a part of the movable arm is within the field of view of the ToF sensor in the closed state.

[0026] In this case, the observation direction of the sensor may be within the rotational movement plane. The observation direction of the sensor may correspond to the optical axis of the sensor. The observation direction may be oriented to face the movable arm of the switch. At least in the closed state, the movable arm may intersect the observation direction of the sensor.

[0027] The control device can be configured to determine that the high-voltage disconnect switch is in the closed state when the determined distance value is less than a predetermined first value, and to determine that the high-voltage disconnect switch is in the open state when the determined distance value is greater than a predetermined second value. Further, the control device can be configured to output an error when the determined distance value is between the predetermined first value and the predetermined second value and exceeds a predetermined time. Generally speaking, for all embodiments described herein, the control device can be configured to output an error when the determination that the switch is neither in the open state nor in the closed state is made beyond a predetermined time.

[0028] In some situations, the above-described arrangement can be advantageous because the movable arm can be tracked over a long distance, thereby enabling the position of the movable arm to be determined in a plurality of states (i.e., in the closed state and the intermediate state).

[0029] The ToF sensor can be arranged such that the movable arm is within the field of view of the ToF sensor in both the open state and the closed state.

[0030] In this case, the sensor can detect the distance to the movable arm whether in the closed state or the open state. The control device can be configured to determine that the high-voltage cut-off switch is in the closed state when the determined distance value is within a predetermined first range, and to determine that the high-voltage cut-off switch is in the open state when the determined distance value is within a predetermined second range.

[0031] In some situations, the above arrangement can be advantageous because the movable arm can be tracked over a long distance, thereby enabling the position of the movable arm to be determined in the open state, the closed state, and the intermediate state.

[0032] The control device can be configured to determine the speed of the movable arm based on the distance value.

[0033] The speed can be determined based on the gradient of the time-dependent distance value. Further, when the sensor includes a two-dimensional pixelated image sensor, the distance values of a plurality of pixels can be considered. In this case, the speed can be determined based on the difference in the distance values of each pixel. For example, the speed can be determined based on the time difference between two events, where the first event corresponds to the movable arm leaving the detection area of the first pixel of the sensor, and the second event corresponds to the movable arm leaving the detection area of the second pixel of the sensor.

[0034] The speed can be used to determine whether the movable arm is moving in the normal mode or whether an error exists. When it is determined that the speed is outside a predetermined range, the control device can output an error signal.

[0035] The ToF sensor can include an image sensor having a plurality of pixels, and the image sensor is configured to output distance values for each one of the plurality of pixels. The control device can be configured to determine whether the high-voltage cut-off switch is in the open state or the closed state based on the distance values of the plurality of pixels.

[0036] For example, the outputs of a plurality of pixels can be used to improve the reliability of the distance value. In this case, the distance value can be determined as the average value of the individual distance values of the individual pixels. However, the individual distance values of the pixels can also be considered independently.

[0037] For example, a plurality of pixels can be used to more accurately determine the position of the movable arm. Each pixel can have its own detection area within the entire field of view of the sensor. In other words, each pixel can output a distance value in a specific predetermined detection area of the pixel. When the sensor is arranged such that the arm moves through the detection area, the individual distance values can be considered to determine which part of the detection area the movable arm is currently located in. For example, the movable arm can be located within a detection area where the distance value is below a predetermined threshold value and also within a detection area where the distance is greater than a predetermined threshold value, and it is determined that the movable arm is not currently located within these areas.

[0038] The ToF sensor can include an image sensor having a plurality of pixels, and the image sensor is configured to output a distance value for each one of the plurality of pixels, and the control device can be configured to determine the speed of the movable arm based on the plurality of distance values of the plurality of pixels.

[0039] The distance can be detected when, for example, the time between a first event detected by a first pixel and a second event detected by a second pixel is taken into account. The two events can be a change in the measured distance value. The two events can also be a change in the measured distance value having a gradient greater than a predetermined value. In this case, it is possible to determine the detection area from which the movable arm has just detached or entered.

[0040] The control device is further configurable to switch on at least one additional sensor in response to a ToF sensor that detects a change in the distance value.

[0041] The additional sensor may be another sensor arranged in the vicinity of the switch. The additional sensor can be configured to measure one or more physical properties and / or physical values in relation to the switching process of the switch. The additional sensor can include at least one of a camera, a light sensor, a temperature sensor, a vibration sensor, an acceleration sensor, a magnetic field sensor, or an acoustic sensor. Furthermore, two or more sensors from the above list may be provided and switched on by the control device. The additional sensor can be switched on to start recording data. In this way, it can be guaranteed that energy is not wasted during the time when the switching process is not executed. In other words, the additional sensor starts data collection and consumes energy only when the switching process is detected.

[0042] The control device is further configurable to switch off at least one additional sensor in response to the ToF sensor detecting that there is no change in the distance value for at least a predetermined time.

[0043] At least one additional sensor may be a sensor that is switched on in response to the ToF sensor detecting a change in the distance value. The predetermined time may be, for example, one day (i.e., 24 hours). If no change is detected in the distance value even after the predetermined time has elapsed, the additional sensor can be switched off to enter the sleep mode. In this mode, no energy is consumed or a reduced amount of energy is consumed. In the sleep mode, no data or a reduced amount of data is recorded by the additional sensor. By doing so, it is possible to ensure that energy is not wasted during the time when the switching process is not executed. In other words, after the predetermined time has elapsed since the end of the last switching process, the additional sensor stops data collection and energy consumption.

[0044] According to a second aspect, a method for determining the position of the movable arm of a high-voltage disconnect switch is provided. The method includes moving the movable arm of the high-voltage disconnect switch to open and close the high-voltage disconnect switch, and determining, by the ToF sensor, a distance value indicating the distance between the ToF sensor and the movable arm. The method further includes determining, based on the distance value, whether the high-voltage disconnect switch is in the open state or the closed state.

[0045] Each of the details and advantageous embodiments of the first aspect described above is also applicable to the method of the second aspect.

[0046] The movable arm can rotate within a plane of rotational motion, and the ToF sensor can be disposed out of the plane and oriented to face the plane such that at least a part of the movable arm is within the field of view of the ToF sensor during at least a part of the movement of the movable arm from the closed state to the open state.

[0047] The movable arm can rotate within a plane of rotational movement, and the ToF sensor can be arranged within the plane and oriented to face the movable arm such that at least a portion of the movable arm is within the field of view of the ToF sensor in the closed state.

[0048] The ToF sensor may be arranged such that the movable arm is within the field of view of the ToF sensor in both the open and closed states.

[0049] The method may further include determining a velocity of the movable arm based on the distance values.

[0050] The ToF sensor can include an image sensor having a plurality of pixels, the image sensor outputs a distance value for each one of the plurality of pixels, and the method may further include determining whether a high voltage disconnect switch is in an open state or a closed state based on the plurality of distance values of the plurality of pixels.

[0051] The ToF sensor can include an image sensor having a plurality of pixels, the image sensor outputs a distance value for each one of the plurality of pixels, and the method may further include determining a velocity of the movable arm based on the plurality of distance values of the plurality of pixels.

[0052] The method may further include switching on at least one additional sensor in response to the ToF sensor detecting a change in the distance value.

[0053] The method may further include switching off at least one additional sensor in response to the ToF sensor detecting no change in the distance value over at least a predetermined time.

[0054] The present disclosure will be further described with reference to the accompanying drawings. These drawings schematically illustrate the following.

Brief Description of the Drawings

[0055]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0056] In the following, in order to provide a complete understanding of the present disclosure, non-limiting specific details are provided. Those skilled in the art should understand that the present disclosure can also be realized in other embodiments that may be different from the details provided below. For example, in the following, specific configurations of high-voltage disconnect switches are described and illustrated, but these should not be understood as limitations. For example, different embodiments and configurations of switches are possible.

[0057] The core idea of the present disclosure is the use of a Time of Flight (ToF) sensor for determining the operating state (open state or closed state) of a high-voltage disconnect switch.

[0058] Time-of-flight ranging technology has led to the development of ToF sensors with a single pixel or multiple pixels. In the latter case, since a three-dimensional image (or depth image) can be recorded, the sensor may also be referred to as a ToF camera. Although the present disclosure will be described in relation to a ToF sensor having a two-dimensional pixelated image sensor (i.e., a sensor having multiple pixels), the present disclosure is not limited to this type of device, and a one-pixel sensor capable of recording only one distance value (i.e., the only time-dependent distance value) at a given time can also be used.

[0059] Commercially available devices enable free programming of multi-pixel ToF circuits for measuring distance and angle.

[0060] The sensor of the present disclosure is based on the time-of-flight (ToF) method, which is the measurement of the time t it takes for a laser pulse to travel a certain distance through a medium (e.g., air). Depending on the distance to the object, each pixel on the image sensor receives the reflected / scattered pulse with a delay. A microcontroller that evaluates the speed, path length D, or surface characteristics uses this information. t = 2 * D / c Here, c is the speed of light in the medium.

[0061] The pulse duration T defines the maximum measurable distance Dmax, i.e., Dmax = c * T / 2 is defined.

[0062] The ToF sensor can include an image sensor having multiple pixels, a laser diode, and a microcontroller. To minimize the influence from the environment, the laser and the image sensor are optimized at a wavelength of 850 nm.

[0063] Depending on the divergence angle α of the optical system of the sensor (including, for example, a lens), the sensor has a region A (field of view), i.e., A = Π * tan2 (α) * D 2 Here, D is the distance, can cover.

[0064] An overall schematic diagram of a system 1 for determining the position of the movable arm 3 of the high-voltage disconnector 5 is shown in FIG. 1. The system 1 includes a high-voltage disconnector 5 and a ToF sensor 7. The high-voltage disconnector 5 includes a movable arm 3 for opening and closing itself, and the ToF sensor 7 is configured to determine a distance value indicating the distance from itself to the movable arm 3. The system 1 further includes a control device 9 configured to determine whether the high-voltage disconnector 5 is in an open state or a closed state based on the distance value.

[0065] The system 1 is incorporated in a substation facility, and the switch 5 provides a disconnector function for the substation facility according to a known basic method. Further, the switch 5 is also operable by an electric actuator (for example, an electric motor) under the control of a control device of the substation facility. For example, the control device for the switch 5 may be the same as the control device 9 for the sensor 7.

[0066] As schematically shown in FIG. 1, when the switch 5 is opened and closed, the arm 3 performs a turning motion (or "rotation"). During such a turning motion, the arm 3 moves within a certain plane (hereinafter referred to as the rotation motion plane).

[0067] In the closed state of the switch 5, a first contact portion 11 provided at one end of the arm 3 physically and electrically contacts a second contact portion 13 of the switch, whereby current can flow through the switch 5. In the open state of the switch 5, the two contact portions 11, 13 are physically separated from each other by air, and current cannot flow. In the following discussion, whether the second contact portion 13 is fixedly provided or the second contact portion 13 itself is provided at the end of the second movable arm of the switch 5 is not very important. The following details are applicable to both situations.

[0068] The sensor 7 is positioned such that when the switch 5 transitions from the closed state to the open state or vice versa from the open state to the closed state, the distance value measured by the sensor 7 changes. For this purpose, at least a part of the arm 3 is within the field of view of the sensor 7 during at least a part of the movement from the closed state to the open state.

[0069] The control device 9 includes a processor 15 and a memory 17. In the memory 17, instructions for causing the processor 15 to execute at least one of the methods described in this specification are stored. In particular, the control device 9 is configured to determine whether the switch 5 is in the open state or the closed state based on the signal received by the sensor 7. At least a part of the control device 9 may be arranged at a location physically separated from the sensor 7 (for example, outside the substation equipment), such as in a server or in the cloud. The following figures focus on the structural arrangement of the switch 5 with respect to the sensor 7, and although the control device 9 is part of the system 1, it is not shown.

[0070] FIG. 2 shows a first embodiment of the arrangement of the sensor 7 with respect to the movable arm 3. The sensor 7 includes a microcontroller, a mount, a laser diode, an image sensor, and an optical system. As one method of clearance detection, as shown in FIG. 2, the sensor 7 can be arranged below the movable arm 3.

[0071] In the embodiment of FIG. 2, the movable arm 3 is configured to rotate within a plane of rotational movement, and the ToF sensor 7 is arranged outside of that plane. In the Cartesian coordinate system defined with respect to FIG. 2, the plane of rotational movement is parallel to the x - y plane. The left - hand part of FIG. 2 shows a side view of the system, and the right - hand part of FIG. 2 shows a plan view of the same system. As shown in FIG. 2, by way of example, the arm 3 (and thus the plane of rotational movement) is arranged 2 m above the floor level.

[0072] The sensor 7 is oriented to face a plane such that at least a part of the movable arm 3 is within the field of view 19 of the ToF sensor 7 during at least a part of the movement of the movable arm 3 from the closed state to the open state.

[0073] The left part of FIG. 2 shows the switch 5 in the closed state, and the right part of FIG. 2 shows the switch in the open state.

[0074] As shown in FIG. 2, the arm 3 performs a pivoting movement to move the switch from the closed state to the open state and vice versa from the open state to the closed state. In the example shown in FIG. 2, the field of view 19 of the sensor 7 is positioned such that a part of the arm 3 is within the field of view 19 in the closed state (see the left part of FIG. 2).

[0075] In the present embodiment and other embodiments discussed in this specification, the sensor 7 may continuously output laser pulses and thus continuously record the distance values evaluated by the control device 9. Accordingly, the control device 9 records the distance values that are time-dependent. When a plurality of pixels are considered, the control device 9 records the time-dependent distance values for each pixel.

[0076] Accordingly, the control device can determine whether the switch 5 is in the closed state or the open state as follows.

[0077] In the one-pixel embodiment, when the detected distance value is below a predetermined threshold, the control device 9 determines that the switch 5 is in the closed state. At all other times, the control device 9 determines that the switch 5 is in the open state.

[0078] In the multi-pixel embodiment, as shown in the right part of FIG. 2, within the field of view of sensor 7, various sub-regions can be defined such that each represents a specific state of switch 5. The sub-regions correspond to one or more detection regions of one or more pixels of sensor 7. When the pixels of each sub-region detect a distance value less than a predetermined threshold, control device 9 determines that arm 3 is located in that sub-region. In this way, for example, it can be determined that arm 3 of switch 5 is in the closed state, or in the spark gap region, or in the safe region, or in the open state. Thereby, an intermediate state between the open state and the closed state can be defined.

[0079] FIG. 3 shows a second embodiment, where sensor 7 is positioned at the same level as movable arm 3. In other words, ToF sensor 7 is arranged within the plane of rotational movement. Switch 5 and its arm 3 may be the same as those described with reference to FIG. 2. However, sensor 7 is positioned 2 m above the floor level within the plane of rotational movement of arm 3. The sensor is oriented to face movable arm 3 such that at least a part of movable arm 3 is within the field of view 19 of ToF sensor 7 in the closed state. In the embodiment of FIG. 3, the observation direction of sensor 7 is perpendicular to arm 3 in the closed state.

[0080] Both the left part and the right part of FIG. 3 are plan views of system 1 (i.e., views along the z direction). The left part of FIG. 3 shows that switch 5 is in the closed state, and the right part of FIG. 3 shows that switch 5 is in the intermediate state. In the open state, arm 3 is oriented along the y direction.

[0081] As shown in FIG. 3, sensor 7 can monitor the distance to arm 3 both when in the closed state and when arm 3 moves away from the closed state towards the open state.

[0082] Therefore, the control device 9 can determine whether the switch 5 is in the closed state or the open state as follows.

[0083] In the single-pixel embodiment, when the detected distance value is less than a predetermined threshold value, the control device 9 determines that the switch 5 is in the closed state. When the distance value is greater than the predetermined threshold value, the control device 9 determines that the switch is in the intermediate state, and when the distance value is greater than a second predetermined threshold value, the control device 9 determines that the switch 5 is in the open position.

[0084] In the multi-pixel embodiment, more pixels can be evaluated, so the reliability of the method can be improved.

[0085] FIG. 4 shows a third embodiment similar to the second embodiment, where the sensor 7 is arranged in the plane of rotation of the arm 3. FIG. 4 shows a plan view along the z-axis. The difference in the arrangement configuration of FIG. 4 from FIG. 3 is that the observation direction of the sensor 7 is in the direction of 45° with respect to the arm 3 in the closed state. In such an arrangement configuration, it is ensured that the arm 3 is within the field of view of the sensor 7 in both the open state and the closed state (both states are shown in FIG. 4).

[0086] Therefore, when the measured distance is within a predetermined range, the control device 9 can determine that the switch 5 is in the closed state, and when the measured distance is within another predetermined range, the control device 9 can determine that the switch 5 is in the open state. The values between the respective ranges can be assigned to the intermediate state of the switch 5.

[0087] Since the switch arm 3 does not operate constantly, a large number of unnecessary data are generated. The ToF sensor 7 can be used in standby mode to acquire data only when there is movement within a predetermined time. This can also be used for triggering other sensors.

[0088] FIG. 5 shows a flowchart of possible interactions with other sensors. When the algorithm starts, the sensors do not form an output unless the ToF sensor 7 records the movement of the switch arm 3. With the first movement of the switch arm 3, all connected sensors are started / resumed, and the movement continues until the arm stops moving for a predetermined time in the off position. When the arm stops moving for a predetermined time in the off position, all sensors are paused again. As shown in FIG. 5, the predetermined time here may be, but is not limited to, one day (24 hours).

[0089] The above method can be regarded as master / slave operation. The ToF sensor 7 is the master sensor that triggers the on / off state of other sensors of the substation equipment. When the distance value measured by the sensor 7 changes, all other sensors (slave sensors) are switched on, and these other sensors record data and form an output. When the distance value measured by the sensor 7 does not change for a predetermined time or more, the other sensors can be switched off again. This can help save energy because the operation of other sensors may consume energy. An example of another sensor is a camera that can start acquiring images when switched on. The operation of FIG. 5 can be controlled by the control device 9. The data of other sensors 7 can be transmitted to the control device 9.

[0090] The stability of the ToF measurement for long-term measurement is shown in FIG. 6. The measurement was performed at about 60,000 measurement points on the metal arm 3 of the high-voltage disconnect switch 5. The sensor 7 continued the measurement for 40 minutes at a constant distance. A standard deviation of 0.0015 m can be derived from the measurement data. This is equal to a rate of 0.68%. The measurement in FIG. 6 shows that the available ToF sensor is sufficiently stable for the purposes described in this disclosure.

[0091] Figure 7 shows the measurements of the sensor 7 implemented with the configuration shown in Figure 2. In this measurement, the ToF sensor 7 was placed 2 m below the movable metal arm 3. While the ToF sensor 7 was taking measurements, the arm 3 moved from the left side (referred to here as TX) to the right side (referred to here as RX). Figure 7 plots the signals (i.e., time-dependent distance values) of three different pixels, namely r(4,2)71, r(5,2)73, and r(6,2)75. These pixels are arranged adjacent to each other on the sensor 7. Depending on which side the arm 3 is moving from, either pixel r(4,2) or r(6,2) supplies a signal first. In Figure 7, the movement from left to right (from TX to RX) and the movement from right to left (from RX to TX) can be observed. Based on the delay between the signal of r(4,2) and the signal of r(6,2), the speed of the arm 3 can be calculated by the control device 9.

[0092] Figure 8 shows the measurements of the sensor 7 implemented with the configuration shown in Figure 4. In this measurement, the sensor 7 was placed at the same level as the metal arm 3, and the distance towards the arm 3 was measured with respect to time. Similar to Figure 7, Figure 8 also shows the curves of three different adjacent pixels of the sensor 7, namely, the curves of r(3,2)81, r(4,2)83, and r(5,2)85.

[0093] For the first 40 seconds, the arm 3 moved away from the sensor 7 and then moved back towards the sensor 7. The three curves 81, 83, 85 represent different pixels, and since the detection areas of these pixels are different from each other, each pixel detects a slightly different part of the arm 3 from other pixels.

[0094] Based on the curves in Figure 8, the position of the arm 3 can be reliably determined. Furthermore, the speed can be determined based on the gradient of one of the curves.

[0095] In one or more embodiments of the present disclosure, as soon as sensor 7 detects the movement of arm 3, sensor 7 starts its algorithm. Next, the microcontroller of sensor 7 stores the status request and the distance measurement values of a predetermined number of pixels in a temporary cache. Also, the distance measurement values may be stored directly in the memory of control device 9.

[0096] The distance is converted into the position of arm 3 in system 1 and its speed as an optional means. At the defined position, control device 9 can activate other sensors / algorithms. The data can be displayed on the screen, on the display of sensor 7 or on control device 9, or stored as a file (e.g., a.txt file) on control device 9 and / or in the cloud.

[0097] Additional lenses can be used to increase or decrease the divergence of sensor 7. Sensor 7 can also be coupled to an optical fiber. Thereby, the distance from the electrical sensor module to the electromagnetic field of switch 5 can be increased.

[0098] Each embodiment described herein provides a reliable technique for determining the state (open state or closed state) of a high-voltage disconnect switch.

Claims

1. A system (1) for determining the position of the movable arm (3) of a high-voltage disconnect switch (5), said system (1) comprising a high-voltage disconnect switch (5), a ToF sensor (7), and a control device (9), said high-voltage disconnect switch (5) comprising a movable arm (3) for opening and closing itself, said ToF sensor (7) being configured to determine a distance value indicative of the distance from itself to said movable arm (3), said control device (9) being configured to determine whether said high-voltage disconnect switch (5) is in an open state or a closed state based on said distance value, said movable arm (3) being configured to rotate within a plane of rotational movement, said ToF sensor (7) being arranged outside said plane and oriented to face said plane such that at least a part of said movable arm (3) is within the field of view of said ToF sensor (7) during at least a part of the movement of said movable arm (3) from said closed state to said open state, System (1).

2. said movable arm (3) being configured to rotate within a plane of rotational movement, said ToF sensor (7) being arranged within said plane and oriented to face said movable arm (3) such that at least a part of said movable arm (3) is within the field of view of said ToF sensor (7) in said closed state, The system (1) according to claim 1.

3. The system (1) according to claim 2, wherein said ToF sensor (7) is arranged such that said movable arm (3) is within the field of view of said ToF sensor (7) in both the open state and the closed state.

4. The system (1) according to any one of claims 1 to 3, wherein said control device (9) is configured to determine the speed of said movable arm (3) based on said distance value.

5. The ToF sensor (7) includes an image sensor having a plurality of pixels, and the image sensor is configured to output a distance value for each one of the plurality of pixels. The control device (9) is configured to determine whether the high-voltage cut-off switch (5) is in an open state or a closed state based on a plurality of distance values of the plurality of pixels. The system (1) according to any one of claims 1 to 4.

6. The ToF sensor (7) includes an image sensor having a plurality of pixels, and the image sensor is configured to output a distance value for each one of the plurality of pixels. The control device (9) is configured to determine the speed of the movable arm (3) based on a plurality of distance values for the plurality of pixels. The system (1) according to claim 4.

7. The control device (9) is further configured to switch on at least one additional sensor in response to the ToF sensor (7) detecting a change in the distance value, according to any one of claims 1 to 6 of the system (1).

8. The control device (9) is further configured to switch off at least one additional sensor in response to the ToF sensor (7) detecting that there is no change in the distance value for at least a predetermined time, according to any one of claims 1 to 7 of the system (1).

9. A method for determining the position of the movable arm (3) of the high-voltage cut-off switch (5), the method comprising: moving the movable arm (3) of the high-voltage cut-off switch (5) to open and close the high-voltage cut-off switch (5); Determining, by the ToF sensor (7), a distance value indicating the distance from the ToF sensor (7) to the movable arm (3); Determining, based on the distance value, whether the high-voltage cut-off switch (5) is in an open state or a closed state; Determining, based on the distance value, the speed of the movable arm (3); A method comprising the above steps.

10. The ToF sensor (7) includes an image sensor having a plurality of pixels, and the image sensor outputs a distance value for each one of the plurality of pixels; The method further includes determining, based on the plurality of distance values of the plurality of pixels, whether the high-voltage cut-off switch (5) is in an open state or a closed state. The method according to claim 9.

11. The ToF sensor (7) includes an image sensor having a plurality of pixels, and the image sensor outputs a distance value for each one of the plurality of pixels; The method further includes determining, based on the plurality of distance values of the plurality of pixels, the speed of the movable arm (3). The method according to claim 9.

12. The method according to any one of claims 9 to 11, further including switching on at least one additional sensor in response to the ToF sensor (7) detecting a change in the distance value.

13. The method according to any one of claims 9 to 12, further including switching off at least one additional sensor in response to the ToF sensor (7) detecting that there is no change in the distance value for at least a predetermined time.

Images