Current mutual inductance type power line monitoring device

Abstract

The invention discloses a current mutual inductance type power line monitoring device which comprises a first winding, a second winding, a magnetic core, a first sampling module, a controllable bridge rectifier circuit, a second sampling module, a load and a control module. The magnetic core is sleeved on a power line to be monitored, and the first winding and the second winding are wound on the magnetic core; the first sampling module is used for collecting current and magnetic flux flowing through the second winding; the two ends of the first winding are electrically connected with the two ends of the load through the controllable bridge rectifier circuit; the second sampling module is used for collecting voltage at two ends of the load and current flowing through the load; the control module is used for adjusting the duty ratio of a switching device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module. According to the invention, it can be ensured that the power line monitoring device obtains sufficient power for power monitoring, and magnetic core saturation can be avoided.

Description

Technical Field

[0001] The present invention belongs to the field of electric power technology, and more specifically, relates to a current mutual inductance type power line monitoring device. Background Art

[0002] With the progress of society and the rapid development of the power industry, new technologies such as smart grids and distribution network automation are becoming increasingly popular. People's requirements for the stability, reliability, and quality of power transmission in power systems are constantly increasing. Therefore, it is necessary to monitor high-voltage transmission lines in real time and deploy various monitoring equipment and indicator equipment to improve the quality of power. However, since high-voltage transmission overhead lines are located above the towers and high-voltage cables are arranged underground, it is difficult to set up power supply, which limits the development of power grid monitoring organizations and intelligence.

[0003] There are several traditional power supply methods for power transmission monitoring equipment: battery power supply, solar power supply, electromagnetic field power supply, voltage transformer power supply and current transformer (CT) power supply. In principle, due to the large current of high-voltage transmission lines, the current transformer power supply method can achieve the maximum theoretical power under good coupling conditions. In addition, the current transformer power supply has the advantages of small size, low cost and easy installation, so it is a very potential power supply method for online equipment.

[0004] However, there are some obvious drawbacks in using current transformers to draw power: (1) Due to the fluctuation of the load of high-voltage transmission lines, the current fluctuation is large, and the ratio of the received current of the current transformer power taking device to the transmission line current is fixed. Therefore, when the transmission line current is low, the power obtained by the power taking device is insufficient. When the transmission line current is high, the magnetic flux in the magnetic core of the current transformer is large, causing the magnetic core to saturate and easily burn the entire device.

[0005] (2) Traditional control methods are not accurate. Since the power draw needs to be limited, the current on the receiving side is distorted and not proportional to the current of the power line. Therefore, it is impossible to infer the line current by measuring the output current of the power draw device, and it is impossible to realize the function of monitoring the power line current. Additional complex equipment is required. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a current mutual inductance power line monitoring device, which can ensure that the power line monitoring device obtains sufficient power for power monitoring and can also avoid core saturation.

[0007] To achieve the above object, the present invention provides a current mutual inductance power line monitoring device, comprising: a first winding, a second winding, a magnetic core, a first sampling module, a controllable bridge rectifier circuit, a second sampling module, a load and a control module; The magnetic core is sleeved on the power line to be monitored, and the first winding and the second winding are wound around the magnetic core; The first sampling module is used to collect the current and magnetic flux flowing through the second winding, which are respectively denoted as I 2 and B; The two AC input ends of the controllable bridge rectifier circuit are electrically connected to the two ends of the first winding respectively, the positive electrode of the controllable bridge rectifier circuit after rectification is electrically connected to the first end of the second sampling module, the negative electrode of the controllable bridge rectifier circuit after rectification is electrically connected to the second end of the second sampling module, and the first end and the second end of the second sampling module are electrically connected to the two ends of the load respectively; The second sampling module is used to collect the voltage across the load and the current flowing through the load, which are respectively denoted as U and I 1 ; The control module is used to adjust the duty cycle of the switch device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module, so that the collected U and I 1 During the process, B is not greater than the saturation magnetic flux of the magnetic core.

[0008] Furthermore, the duty cycle of the switch device in the controllable bridge rectifier circuit is adjusted according to the sampling data of the first sampling module and the second sampling module, so that the sampling data of U and I 1 The process, B is not greater than the saturation magnetic flux of the magnetic core, comprises the steps of: S1, controlling the first sampling module to perform sampling, and obtaining sampling data I of the first sampling module 2 and B; S2, the saturation magnetic flux of the magnetic core is recorded as B max , if B>B max , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit and return to S1. If B≤B max , then execute S3; S3, control the second sampling module to perform sampling, and obtain the sampling data U and I of the second sampling module 1 ; S4, the working voltage of the load is recorded as U set , if U>U set , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If U≤U set , then execute S5; S5, according to U and I 1 Calculate the power of the load, and record the sampling current of the second sampling module in step S3 in the previous cycle as I 1(t-1), the power of the load in step S5 of the previous cycle is recorded as P(t-1), and the sampling current of the second sampling module in step S3 of the current cycle is recorded as I 1 (t), the power of the load in step S5 in the current cycle is recorded as P(t); S6, calculate P(t)-P(t-1), I 1 (t)-I 1 (t-1); S7, if P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)>0, then reduce the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)≤0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)>0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)≤0, the duty cycle of the switching device in the controllable bridge rectifier circuit is reduced, and then the process returns to S1.

[0009] Further, the control module is also used to control the I 2 To calculate the current of the power line in each cycle, the current of the power line is recorded as I 3 , I 3 =I 2 ×N 2 , N 2 is the number of turns of the second winding.

[0010] Furthermore, the control module includes a GSM communication module, and the GSM communication module is used to transmit the current calculation value of the power line to a back-end monitoring system.

[0011] Furthermore, the number of turns and the wire diameter of the first winding are determined according to the working current of the load and the current range of the power line, and the working current of the load is recorded as I 4 , the current range of the power line is recorded as I min ~I max , the number of turns of the first winding is recorded as N 1 , N 1 =I min / I 4, the wire diameter of the first winding must satisfy the requirement that the maximum current that the first winding can withstand is greater than or equal to I max / N 1 .

[0012] Furthermore, the number of turns of the second winding is not less than the number of turns of the first winding, and the wire diameter of the second winding is not greater than that of the first winding.

[0013] Furthermore, the magnetic core includes at least one opening which can be switched between an open state and a closed state.

[0014] Furthermore, the surfaces on both sides of the opening of the magnetic core are flat surfaces.

[0015] Further, the control module includes a controller and a drive module, and the controllable bridge rectifier circuit includes a first diode, a second diode, a first switch tube and a second switch tube. The cathode of the first diode is electrically connected to the cathode of the second diode, forming a positive electrode of the controllable bridge rectifier circuit after rectification, the source or emitter of the first switch tube is electrically connected to the source or emitter of the second switch tube, forming a negative electrode of the controllable bridge rectifier circuit after rectification, the anode of the first diode is electrically connected to the drain or collector of the first switch tube, the anode of the second diode is electrically connected to the drain or collector of the second switch tube, forming two AC input ends of the controllable bridge rectifier circuit, the gate or base of the first switch tube and the gate or base of the second switch tube are both electrically connected to the control signal output end of the drive module, and the signal input end of the drive module is electrically connected to the controller.

[0016] Furthermore, the load is also used to supply power to the first sampling module, the second sampling module and the control module.

[0017] In general, the above technical solutions conceived by the present invention have beneficial effects compared with the prior art: (1) During the monitoring process, no matter how much current flows in the power line or how much power is drawn, the magnetic core will not be saturated during the power drawing process, and the magnetic flux will never exceed the saturation magnetic flux.

[0018] (2) When the power line current is low, the present invention can automatically track the maximum power and output power to the load as high as possible; when the line current is high, the present invention can automatically control the output voltage and power to protect the power line monitoring device and the load.

[0019] (3) The power line monitoring device can collect the current of the power line in real time and send it remotely to the monitoring center of the power grid. The overall design has low cost and high reliability, and is easy to apply and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of the circuit structure of a power line monitoring device according to an embodiment of the present invention; Figure 2 is a schematic diagram of the control principle of a control module of a power line monitoring device according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the control principle of a control module of a power line monitoring device according to another embodiment of the present invention.

[0021] In all the drawings, the same reference numerals are used to denote the same elements or structures, wherein 1 is a first winding; 2 is a second winding; 3 is a power line; 4 is a magnetic core; D 1 - the first diode; D 2 - second diode; M 1 —The first switch tube; M 2 —Second switch tube; C—capacitor; R L —Load, R 1 —Sampling resistor. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] In the description of the embodiments of the present application, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. "Multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] Unless otherwise specified, "plurality" means two or more.

[0025] The terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or equipment comprising a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules not clearly listed or inherent to these processes, methods, products or equipment.

[0026] The naming or numbering of the steps in the embodiments of the present invention does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The execution order of the named or numbered process steps can be changed according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0027] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] The embodiment of the present invention provides a current mutual inductance power line monitoring device, comprising: a first winding, a second winding, a magnetic core, a first sampling module, a controllable bridge rectifier circuit, a second sampling module, a load and a control module; The magnetic core is sleeved on the power line to be monitored, and the first winding and the second winding are wound around the magnetic core.

[0029] The first sampling module is used to collect the current and magnetic flux flowing through the second winding, which are respectively denoted as I 2 and B; The two AC input ends of the controllable bridge rectifier circuit are electrically connected to the two ends of the first winding respectively, the positive pole of the controllable bridge rectifier circuit after rectification is electrically connected to the first end of the second sampling module, the negative pole of the controllable bridge rectifier circuit after rectification is electrically connected to the second end of the second sampling module, and the first end and the second end of the second sampling module are electrically connected to the two ends of the load respectively.

[0030] The second sampling module is used to collect the voltage across the load and the current flowing through the load, which are denoted as U and I respectively. 1 .

[0031] The control module is used to adjust the duty cycle of the switch device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module, so that the sampling U and I 1 During the process, B is not greater than the saturation magnetic flux of the magnetic core.

[0032] Figure 1 1 is a circuit diagram of a current mutual inductance power line monitoring device according to another embodiment of the present invention. The current mutual inductance power line monitoring device comprises a first winding 1, a second winding 2, a magnetic core 4, a first diode D 1 , the second diode D 2 , the first switch tube M 1 , the second switch tube M 2, capacitor C, voltage and current sampling module, load R L , controller, drive module, sampling resistor R 1 , flux sampling module, current sampling module, GSM communication module.

[0033] The first diode D 1 , the second diode D 2 , the first switch tube M 1 , the second switch tube M 2 A controllable bridge rectifier circuit is formed.

[0034] Sampling resistor R 1 , flux sampling module and current sampling module serve as the first sampling circuit.

[0035] The capacitor C and the voltage and current sampling module serve as the second sampling circuit.

[0036] The controller, drive module and GSM communication module constitute the control module.

[0037] The load is also used to supply power to the first sampling module, the second sampling module and the control module.

[0038] The power line 3 is a power transmission line of a power grid, which may be an overhead line or a cable. Since the power line monitoring device is installed online and is not connected to a tower or the ground, it forms an equipotential with the power line, so the voltage level of the power line is not limited.

[0039] The first winding 1 and the second winding 2 are wound by enameled wire or insulated wire. The number of turns and the wire diameter of the first winding are determined according to the working current of the load and the current range of the power line. Specifically, the working current of the load is recorded as I 4 , the current range of the power line is recorded as I min ~I max , the number of turns of the first winding 1 is recorded as N 1 , N 1 =I min / I 4 , then the wire diameter of the first winding 1 must satisfy the requirement that the maximum current that the first winding 1 can withstand is greater than or equal to I max / N 1 .

[0040] For example, the working voltage and current required by the load are 5V and 1A respectively, with a total power consumption of 5W. The current of the transmission line is 100A-500A. Then the number of turns of the first winding 1 must ensure that sufficient power can still be obtained at the minimum current. Therefore, the number of turns of the first winding 1 = the minimum current of the second winding / the current required by the load = 100A / 1A = 100 turns. If the number of turns of the first winding 1 exceeds 100 turns, it will not be able to provide enough power for the load at the minimum current of the transmission line.

[0041] The wire diameter of the first winding 1 is designed according to the maximum current flowing through it. The maximum current of the first winding 1 = the maximum current of the transmission line / the number of turns of the second winding = 500A / 100 turns = 5A. Therefore, the first winding 1 needs to select a wire that can pass 5A current.

[0042] The number of turns of the second winding 2 is not less than that of the first winding 1, and the wire diameter of the second winding 2 is not greater than that of the first winding 1, for the following reasons.

[0043] First, the second winding 2 does not transmit power, so it does not require a large current, and the current flowing through it can be less than that of the first winding 1. Increasing the number of turns of the second winding 2 can reduce the current, thereby selecting a wire diameter with a lower current carrying capacity, thereby reducing cost and volume. Therefore, when the current of the transmission line is constant, the number of turns of the second winding 2 is not less than the number of turns of the first winding 1. For example, when the current of the transmission line is 100A-500A, the number of turns of the second winding 2 can be greater than the 100 turns of the first winding 1. Set to 500 turns, at this time the current variation range of the second winding 2 is 0.2A-1A, and a wire that can pass 1A current can be selected, and the wire diameter is thinner than the first winding 1.

[0044] Second, the second winding 2 has no discharge circuit, and to prevent the sampling resistor voltage of the winding from being too high, the current of the second winding 2 needs to be relatively small. This can be achieved by increasing the number of turns of the second winding 2, because the number of turns of the second winding = transmission line current / second winding current.

[0045] Furthermore, the magnetic core 4 includes at least one opening that can be switched between an open state and a closed state, so that the power line monitoring device can be inserted into the power line 3 without powering off.

[0046] Furthermore, the surfaces on both sides of the opening of the magnetic core are flat surfaces, and it can be considered that there is no magnetic leakage when pressed. The material of the magnetic core is not limited, but using a magnetic core material with high magnetic permeability will achieve better performance.

[0047] The first diode D 1 and the second diode D 2 They can all be conventional diodes with uncontrolled rectification characteristics. 1 and the second switch tube M 2 They can all be fully controlled devices, such as MOS tubes, triodes, IGBTs, etc. Capacitor C is a filter capacitor, which can be a polarized capacitor or a non-polarized capacitor. Usually, this capacitance value is very large, and it can be a capacitor array formed by connecting multiple independent capacitor elements in parallel. In order to stabilize the power supply voltage, the capacitance value should be greater than 30000uF, and 80000uF or more is recommended to achieve the best voltage stabilization effect.

[0048] The function of the voltage and current sampling module is to collect DC voltage and current and convert them into signals that can be accepted by the controller.

[0049] Load R L It is the part that receives energy, which can be any online device or a pure resistor.

[0050] The controller consists of a control chip and its peripheral circuits. It can be a conventional single-chip microcomputer, MCU, DSP, etc., but it must have input and output ports.

[0051] The driving module is responsible for receiving the signal from the controller and generating the first switch tube M 1 and the second switch tube M 2 The drive module has different implementation schemes depending on the switch tube model.

[0052] Sampling resistor R 1 The function of the controller is to convert the current signal into a voltage signal. The converted voltage signal is processed by the flux sampling module and the current sampling module. The specific processing circuit can be implemented by an operational amplifier or a chip, and the processed signal can be directly received by the controller.

[0053] The function of the GSM communication module is to convert the data sent by the controller into wireless communication and send it out. At this time, the monitoring center of the power grid can receive this data, thus realizing the long-distance transmission of power line information.

[0054] The connection mode and working principle between the modules in the embodiment of the present invention are as follows: The magnetic core 4 is sleeved on the power line 3 and locked. At this time, the power line 3 becomes the fourth winding on the magnetic core, and its number of turns is 1. The first winding 1 and the second winding 2 are wound on the same magnetic core. At this time, the three windings are tightly coupled. Therefore, induced current is generated in both the first winding 1 and the second winding 2.

[0055] The first diode, the second diode, the first switch tube, and the second switch tube form a controllable bridge rectifier circuit. Among them, the cathodes of the first diode and the second diode are electrically connected to form the positive electrode after rectification. The source or emitter of the first switch tube is electrically connected to form the negative electrode after rectification. The anode of the first diode is electrically connected to the drain or collector of the first switch tube, and the anode of the second diode is electrically connected to the drain or collector of the second switch tube, forming two AC input ends of the rectifier bridge, which are electrically connected to the first winding 1. The gate or base of the first switch tube and the gate or base of the second switch tube are electrically connected to the control signal output end of the drive module, and the signal input end of the drive module is electrically connected to the controller. The two ends of the capacitor are respectively connected to the positive and negative electrodes after rectification. The voltage and current sampling modules are respectively connected to the positive and negative electrodes after rectification, and the signal output end is connected to the controller. Load RL The positive and negative ends are electrically connected to the positive and negative ends of the rectified battery respectively.

[0056] The two ends of the second winding 2 are connected to the sampling resistor R 1 The input ends of the flux sampling module and the current sampling module are connected to the sampling resistor R 1 The power supply ends of the magnetic flux sampling module and the current sampling module are respectively connected to the positive and negative poles of the first winding 1 after rectification. The output signal ends of the magnetic flux sampling module and the current sampling module are connected to the controller. The input end of the GSM communication module is connected to the output end of the controller.

[0057] The control module is used to adjust the duty cycle of the switch device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module, so that the sampling U and I 1 During the process, B is not greater than the saturation magnetic flux of the magnetic core.

[0058] Specific control steps include Figure 2 As shown, including: S1, control the first sampling module to perform sampling, and obtain the sampling data I of the first sampling module 2 and B. Specifically, it is completed by the magnetic flux sampling module and the current sampling module respectively. The magnetic flux obtained by sampling is B and the current is I 2 .

[0059] S2, the saturation flux of the core is recorded as B max , if B>B max , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit and return to S1. If B≤B max , then execute S3. In this way, the subsequent steps collect U and I 1 During the process, B is not greater than the saturation magnetic flux of the magnetic core.

[0060] S3, control the second sampling module to perform sampling, and obtain the sampling data U and I of the second sampling module 1 The specific implementation is done by the voltage and current sampling module. The sampled load voltage is U and the load current is I 1 .

[0061] S4, the working voltage of the load is recorded as U set , if U>U set , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If U≤U set , then execute S5.

[0062] S5, according to U and I 1 Calculate the power of the load and record the sampling current of the second sampling module in step S3 in the previous cycle as I 1(t-1), the power of the load in step S5 of the previous cycle is recorded as P(t-1), and the sampling current of the second sampling module in step S3 of the current cycle is recorded as I 1 (t), the power of the load in step S5 in the current cycle is recorded as P(t). In other words, the power and load current values ​​of a cycle are retained, that is, "sample and hold".

[0063] S6, calculate P(t)-P(t-1), I 1 (t)-I 1 (t-1). Subtract the power of the two cycles and the current of the two cycles. The value of the previous cycle is used as the subtrahend and the real-time value is used as the minuend.

[0064] S7, determine whether P(t)-P(t-1) is greater than 0, and determine whether I 1 (t)-I 1 (t-1) is greater than 0. If P(t)-P(t-1)>0, it means that the power has increased, otherwise the power has not increased. 1 (t)-I 1 (t-1)>0, it means that the current has increased, otherwise the current has not increased. If P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)>0, then reduce the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)≤0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)>0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)≤0, the duty cycle of the switching device in the controllable bridge rectifier circuit is reduced, and then returns to S1 to enter the next cycle.

[0065] The key to executing the above control steps is to adjust the duty cycle of the switch device in the bridge rectifier circuit. Its principle is that the direction of current flow can be controlled according to the full control characteristics of the switch device. When the first switch tube and the second switch tube are both in the off state, the current will flow through their anti-parallel diodes. At this time, the first diode, the second diode, the first switch tube, and the second switch tube form a controllable bridge rectifier circuit. Therefore, the current flows directly to the load side, causing the voltage on the load side to rise. When the first switch tube and the second switch tube are both in the on state, the current no longer flows through the anti-parallel diode, but flows through the two switch tubes at the same time, so that the current forms a loop in the first winding. At this time, the current is no longer output to the load side, thereby reducing the voltage on the load side. Controlling the duty cycle of the two switch devices is to control their on and off time, thereby controlling the voltage and power of the load, and then controlling the load to work in the maximum power power-taking state, while ensuring that the magnetic core works in an unsaturated state.

[0066] The control module is also used to adjust the I 2 To calculate the current of the power line in each cycle. The current calculation of the power line will be processed by the controller and sent out through the GSM module.

[0067] The current of the power line is denoted as I 3 , I 3 =I 2 ×N 2 , N 2 is the number of turns of the second winding.

[0068] In another embodiment, the distance between the two side surfaces of the opening of the magnetic core is adjustable. The magnetic core is composed of two arc-shaped magnetic cores, and the distance between the two side surfaces of the opening of the magnetic core is adjusted by driving one of the arc-shaped magnetic cores to move through a motor. Increasing the distance between the two side surfaces of the opening of the magnetic core can weaken the coupling between the windings, thereby limiting the power drawn by the load, and can also limit the magnetic flux of the magnetic core. Therefore, increasing the distance between the two side surfaces of the opening of the magnetic core has a similar effect to increasing the duty cycle of the switching device. In this embodiment, increasing the duty cycle of the switching tube in the aforementioned steps can be replaced by increasing the distance between the two side surfaces of the opening of the magnetic core, and reducing the duty cycle of the switching tube can be replaced by reducing the distance between the two side surfaces of the opening of the magnetic core.

[0069] During the monitoring process, the distance between the surfaces on both sides of the opening or the duty cycle of the switching device in the controllable bridge rectifier circuit can be adjusted.

[0070] In another embodiment, a control process is provided by combining adjusting the distance between the two side surfaces of the opening and adjusting the duty cycle of the switching device in the controllable bridge rectifier circuit.

[0071] like Figure 3As shown, the specific control steps include: S1, control the first sampling module to perform sampling, and obtain the sampling data I of the first sampling module 2 and B. Specifically, it is completed by the magnetic flux sampling module and the current sampling module respectively. The magnetic flux obtained by sampling is B and the current is I 2 .

[0072] S2, the saturation flux of the core is recorded as B max , if B>B max , then continue to determine whether B is greater than B max 110% of B / B max >110%, the distance between the two sides of the opening of the core is increased, so that B decreases rapidly and returns to S1. If 100% max >110%, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit and return to S1. If B≤B max , then execute S3. In this way, the subsequent steps collect U and I 1 During the process, B is not greater than the saturation magnetic flux of the magnetic core.

[0073] S3, control the second sampling module to perform sampling, and obtain the sampling data U and I of the second sampling module 1 The specific implementation is done by the voltage and current sampling module. The sampled load voltage is U and the load current is I 1 .

[0074] S4, the working voltage of the load is recorded as U set , if U>U set , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If U≤U set , then execute S5.

[0075] S5, according to U and I 1 Calculate the power of the load and record the sampling current of the second sampling module in step S3 in the previous cycle as I 1 (t-1), the power of the load in step S5 of the previous cycle is recorded as P(t-1), and the sampling current of the second sampling module in step S3 of the current cycle is recorded as I 1 (t), the power of the load in step S5 in the current cycle is recorded as P(t). In other words, the power and load current values ​​of a cycle are retained, that is, "sample and hold".

[0076] S6, calculate P(t)-P(t-1), I 1 (t)-I 1 ​(t-1). Subtract the power of the two cycles and the current of the two cycles. The value of the previous cycle is used as the subtrahend and the real-time value is used as the minuend.

[0077] S7, determine whether P(t)-P(t-1) is greater than 0, and determine whether I 1 (t)-I 1 (t-1) is greater than 0. If P(t)-P(t-1)>0, it means that the power has increased, otherwise the power has not increased. 1 (t)-I 1 (t-1)>0, it means that the current has increased, otherwise the current has not increased. If P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)>0, then reduce the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)>0, and I 1 (t)-I 1 (t-1)≤0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)>0, then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If P(t)-P(t-1)≤0, and I 1 (t)-I 1 (t-1)≤0, the duty cycle of the switching device in the controllable bridge rectifier circuit is reduced, and then returns to S1 to enter the next cycle.

[0078] The control module is also used to adjust the I 2 To calculate the current of the power line in each cycle, the current of the power line is recorded as I 3 , I 3 =I 2 ×N 2 ×(d+k),N 2 is the number of turns of the second winding, d is the distance between the two sides of the opening of the magnetic core, the default value is 0, and k is the adjustment coefficient of the magnetic core opening distance, the default value is 1. If the magnetic core opening is not adjusted, the calculation formula can also be expressed as I 3 =I 2 ×N 2 If there is a distance between the two sides of the opening of the magnetic core, the coupling between the second winding and the power line is weakened, and the I 2 Computation I 3 The core opening distance adjustment coefficient k is needed for conversion. The value of k depends on the specific type and size of the core selected. Before use, you can test it first, determine k by curve fitting, and write it into the control module.

[0079] In another embodiment, a current mutual inductance power line monitoring device is integrated with a positioning module and a gravity sensor, the positioning module is used to collect the position information of the power line, and the gravity sensor is used to collect the acceleration information of the power line. The power line monitoring device transmits the information of the positioning module and the gravity sensor to the back-end monitoring system, and the back-end monitoring system can calculate the inclination angle of the tower where the power line is located based on the position information and the acceleration information.

[0080] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A current mutual inductance power line monitoring device, characterized in that: include: A first winding, a second winding, a magnetic core, a first sampling module, a controllable bridge rectifier circuit, a second sampling module, a load and a control module; The magnetic core is sleeved on the power line to be monitored, and the first winding and the second winding are wound around the magnetic core; The first sampling module is used to collect the current and magnetic flux flowing through the second winding, which are respectively denoted as I2 and B; The two AC input ends of the controllable bridge rectifier circuit are electrically connected to the two ends of the first winding respectively, the positive electrode of the controllable bridge rectifier circuit after rectification is electrically connected to the first end of the second sampling module, the negative electrode of the controllable bridge rectifier circuit after rectification is electrically connected to the second end of the second sampling module, and the first end and the second end of the second sampling module are electrically connected to the two ends of the load respectively; The second sampling module is used to collect the voltage across the load and the current flowing through the load, which are respectively denoted as U and I1; The control module is used to adjust the duty cycle of the switch device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module, so that during the collection of U and I1, B is not greater than the saturation magnetic flux of the magnetic core.

2. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The step of adjusting the duty cycle of the switch device in the controllable bridge rectifier circuit according to the sampling data of the first sampling module and the second sampling module so that B is not greater than the saturation magnetic flux of the magnetic core during the process of collecting U and I1 comprises the following steps: S1, controlling the first sampling module to perform sampling, and obtaining sampling data I2 and B of the first sampling module; S2, the saturation magnetic flux of the magnetic core is recorded as B max , if B>B max , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit and return to S1. If B≤B max , then execute S3; S3, controlling the second sampling module to perform sampling, and obtaining sampling data U and I1 of the second sampling module; S4, the working voltage of the load is recorded as U set , if U>U set , then increase the duty cycle of the switch device in the controllable bridge rectifier circuit. If U≤U set , then execute S5; S5, calculating the power of the load according to U and I1, recording the sampling current of the second sampling module in step S3 in the previous cycle as I1(t-1), recording the power of the load in step S5 in the previous cycle as P(t-1), recording the sampling current of the second sampling module in step S3 in the current cycle as I1(t), recording the power of the load in step S5 in the current cycle as P(t); S6, calculate P(t)-P(t-1), I1(t)-I1(t-1); S7, if P(t)-P(t-1)>0, and I1(t)-I1(t-1)>0, then reduce the duty cycle of the switching device in the controllable bridge rectifier circuit; if P(t)-P(t-1)>0, and I1(t)-I1(t-1)≤0, then increase the duty cycle of the switching device in the controllable bridge rectifier circuit; if P(t)-P(t-1)≤0, and I1(t)-I1(t-1)>0, then increase the duty cycle of the switching device in the controllable bridge rectifier circuit; if P(t)-P(t-1)≤0, and I1(t)-I1(t-1)≤0, then reduce the duty cycle of the switching device in the controllable bridge rectifier circuit, and then return to S1.

3. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The control module is also used to calculate the current of the power line in each cycle according to I2 of each cycle, and record the current of the power line as I3, I3=I2×N2, N2 is the number of turns of the second winding.

4. A current mutual induction power line monitoring device as claimed in claim 3, characterized in that: The control module includes a GSM communication module, and the GSM communication module is used to transmit the current calculation value of the power line to the back-end monitoring system.

5. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The number of turns and the wire diameter of the first winding are determined according to the working current of the load and the current range of the power line. The working current of the load is recorded as I4, and the current range of the power line is recorded as I min ~I max , the number of turns of the first winding is recorded as N1, N1=I min / I4, the wire diameter of the first winding must satisfy the requirement that the maximum current that the first winding can withstand is greater than or equal to I max / N1.

6. A current mutual induction power line monitoring device as claimed in claim 5, characterized in that: The number of turns of the second winding is not less than the number of turns of the first winding, and the wire diameter of the second winding is not greater than that of the first winding.

7. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The magnetic core includes at least one opening that can be switched between an open state and a closed state.

8. A current mutual induction power line monitoring device as claimed in claim 7, characterized in that: The surfaces on both sides of the opening of the magnetic core are flat surfaces.

9. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The control module includes a controller and a drive module. The controllable bridge rectifier circuit includes a first diode, a second diode, a first switch tube and a second switch tube. The cathode of the first diode is electrically connected to the cathode of the second diode, forming a positive electrode of the controllable bridge rectifier circuit after rectification. The source or emitter of the first switch tube is electrically connected to the source or emitter of the second switch tube, forming a negative electrode of the controllable bridge rectifier circuit after rectification. The anode of the first diode is electrically connected to the drain or collector of the first switch tube, and the anode of the second diode is electrically connected to the drain or collector of the second switch tube, forming two AC input ends of the controllable bridge rectifier circuit. The gate or base of the first switch tube and the gate or base of the second switch tube are both electrically connected to the control signal output end of the drive module, and the signal input end of the drive module is electrically connected to the controller.

10. A current mutual induction power line monitoring device as claimed in claim 1, characterized in that: The load is also used to supply power to the first sampling module, the second sampling module and the control module.

Images