A method and system for adaptively switching the ratio of current transformers in power plants

Abstract

A method and system for adaptively switching the transformation ratio of a current transformer in a power plant, relating to the field of wiring of a metering device. The invention comprises a secondary circuit of a current transformer with a bypass, a signal acquisition and analysis module, a command decision module and a switch array. The secondary circuit of the current transformer with a bypass is connected to the input end of the signal acquisition and analysis module; the output end of the signal acquisition and analysis module is connected to the input end of the command decision module, and the current and power data in the secondary circuit of the current transformer with a bypass are collected to obtain the direction and magnitude of the power exchanged between the metering point and the power grid; the command decision module is connected to the switch array, and receives the current and power information returned by the signal acquisition and analysis module, analyzes and calculates the current and power information, and converts the calculation results into action instructions and sends them to the switch array. The invention ensures that the transformation ratio of the current transformer matches the overall operating state through adaptive switching of the transformation ratio of the current transformer, thereby improving the standardization and accuracy of the operation of the metering device.

Description

Technical Field

[0001] The invention relates to the technical field of metering device wiring, in particular to the wiring of an electric energy metering device of a power plant with switching between upper and lower grid states, and specifically to a method and system for adaptively switching the transformation ratio of a current transformer of a power plant. Background Art

[0002] Due to its own operating mode, resource limitations or dispatch instructions, the power generation of a power plant is an unstable variable, but its power consumption remains relatively stable. Therefore, in general, there are two possibilities for the direction of the power flow between the power plant and the power grid: ① When the power generation is greater than the power consumption of the power plant, the metering points of the power plant are generally in an online state; ② When the power generation is less than the power consumption of the power plant, the metering points of the power plant are generally in an offline state.

[0003] In the current power plant scenario, the upper and lower grid metering points are required to be set at the property boundary point. Therefore, a combined setting method is usually adopted, that is, the upper and lower grid metering points are merged, sharing the same set of transformers and secondary circuits, and only special electric energy meters for the upper and lower grids are set at the electric energy meters.

[0004] Although this metering device configuration method can meet the requirements of separately measuring the forward and reverse power in the on-grid and off-grid states, the shared transformer method is difficult to meet the requirements of the industry standard DL / T448-2016 "The selection of the transformer's rated secondary load should ensure that the actual load connected to its secondary circuit is within the range of 25% to 100% of the rated secondary load". Because the total off-grid load of the power plant will not exceed the total power consumption of the plant, and the total on-grid load usually depends on the installed capacity and the start-stop plan, and can be close to the total installed capacity at the maximum, the load difference between the on-grid and off-grid states is very large, usually tens, hundreds or even thousands of times. In order to ensure safety and take into account the power plant's tidal state under normal conditions, the current transformer ratio of the power plant is usually set according to the total installed capacity. Therefore, in the off-grid state, the secondary circuit of the current transformer is usually in a light-load state, which will lead to an increase in metering errors. In order to solve the above technical problems, the present invention provides a method and system for adaptive switching of the current transformer ratio of a power plant. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems raised in the background technology, and to provide a method and system for adaptively switching the transformation ratio of a current transformer in a power plant.

[0006] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0007] A power plant current transformer ratio adaptive switching system comprises a current transformer secondary circuit with bypass, a signal acquisition and analysis module, a command decision module and a switch array. The current transformer secondary circuit with bypass is connected to the input end of the signal acquisition and analysis module to realize the electrical connection between the current transformer and the electric energy meter. The output end of the signal acquisition and analysis module is connected to the input end of the command decision module to collect the wire current and power data flowing in the secondary circuit of the current transformer with bypass and obtain the direction and size of the power exchanged between the current customer metering point and the power grid. The command decision module is connected to the switch array to receive the current and power information returned by the signal acquisition and analysis module, analyze and calculate the current and power information, and convert the calculation results into action instructions and send them to the switch array.

[0008] Furthermore, the secondary circuit of the current transformer with bypass includes a secondary winding of the current transformer, an array switch and a terminal block of a metering panel / metering cabinet. The secondary winding of the current transformer is connected to the array switch and the terminal block of the metering panel / metering cabinet through a wire, and the output end of the array switch is connected to the terminal block of the metering panel / metering cabinet through a wire.

[0009] Furthermore, the signal acquisition and analysis module includes a micro power transformer / current transformer and a power direction relay. The front end is installed in a surrounding manner on the current conductor behind the lower terminal of the test junction box to measure the size and direction of the current signal in the metering circuit at this time. The back end is connected to the I / O interface of the command decision module by means of a signal line / wire.

[0010] Furthermore, the switch array includes a light-emitting diode, a light-sensitive sensing circuit, a signal line, a control line, and a controlled switch. The controlled switch is connected in series with the light-emitting diode. When the controlled switch is turned on, current flows, and the light-emitting diode emits a light signal. The light signal is sensed by the light-sensitive sensing circuit, and the sensing result is sent to the instruction decision module via the signal line.

[0011] Furthermore, the command decision module, the signal acquisition and analysis module and the switch array are all installed on the out-of-meter line that is required to be used in each ratio secondary circuit of the current transformer.

[0012] Furthermore, it also includes a state monitoring module, the input end of the state monitoring module is connected to the switch array, and the output end is connected to the instruction decision module. The state monitoring module is used to monitor the on and off state of each switch in the switch array and return the monitoring result to the instruction decision module.

[0013] Furthermore, it also includes an abnormal warning module, the input end of the abnormal warning module is connected to the instruction decision module by wireless communication, and is used to give warning information in the form of sound and light for the instruction sent by the instruction decision module.

[0014] Furthermore, the abnormal warning module is installed in the metering screen cabinet.

[0015] A method for adaptively switching the transformation ratio of a current transformer in a power plant comprises the following steps:

[0016] Step 1: Lay out and install the secondary circuit of the current transformer with bypass;

[0017] Step 2: The signal acquisition and analysis module collects the wire current and power data flowing in the secondary circuit of the current transformer through the current sensor and the power direction relay, and transmits the collected data to the command decision analysis module;

[0018] Step 3: The command decision analysis module determines and analyzes the current and power information uploaded by the signal acquisition analysis module, and determines whether the operation mode has changed;

[0019] Step 4: If the result of the judgment in step 3 is that the operation mode has not changed, then the process ends; otherwise, the command decision module analyzes and determines the applicable current transformer ratio, and the command decision module sends a closing command to the switch array according to the determined applicable current transformer ratio, and the switch array performs a closing operation;

[0020] Step 5: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful;

[0021] Step 6: If the switch array fails to perform the closing operation in step 5, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module ends after sending out an audible and visual warning message; otherwise, the instruction decision module sends a disconnection instruction to the switch array, and the switch array performs the disconnection operation;

[0022] Step 7: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful;

[0023] Step 8: If the result of step 7 is that the operation is successful, the process ends; otherwise, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module sends an audible and visual warning message and the process ends.

[0024] Working principle and beneficial effects of the present invention:

[0025] (1) The present invention realizes the identification and monitoring of the power plant and the power grid flow direction through the design of the secondary circuit of the current transformer with bypass, and takes targeted measures accordingly to ensure that the current transformer ratio matches the overall operating status, thereby improving the standardization and accuracy of the operation of the metering device; the stable and rapid switching of the wiring topology of the secondary circuit of the current transformer is realized through the switch array, and the switching of the transformer ratio is completed without ensuring that the current circuit is open. Compared with the traditional mode that requires power outage for ratio switching, the switching is more convenient and less likely to affect the customer's primary equipment.

[0026] (2) The present invention adopts a transition connection method to ensure that there is only one secondary circuit corresponding to the applicable transformation ratio connected to the electric energy meter during operation through the design of the secondary circuit of the current transformer with bypass. Without affecting the electrical parameters of the secondary circuit of the current transformer, the rapid switching of the transformation ratio of the current transformer for metering is successfully achieved through secondary side operation. Compared with the traditional switching method which often requires power outage to operate the current transformer wiring cabinet, the operation is greatly simplified and the risk is reduced, which makes it possible for the current transformer to be adaptively switched frequently according to the customer's operating status.

[0027] (3) The present invention is aimed at power plant-type customers, that is, customers who have both online and offline operation modes. Without increasing the investment in transformers, the present invention can intelligently determine the applicable current transformer ratio based on the customer's current power direction, current size and other data, thereby increasing the proportion of operating load in the 25% to 100% segment, and effectively improving the accuracy of electricity metering.

[0028] (4) The present invention adopts a switch array method, using a "double insurance" method of command strategy and status monitoring to ensure that the secondary circuit of the current transformer does not open at any time during the switching process, and sends alarm information according to the severity of abnormal conditions such as failure of the switch array. Compared with the existing technical means for realizing wiring line selection, multi-head switches are mostly used. In the process of connecting line switching, there is inevitably a current circuit disconnection point. The only difference is the length of the open circuit time determined by the action speed and the contact spacing. The present invention can effectively reduce the operation risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a principle block diagram of the switching system of the present invention;

[0030] Figure 2 It is a principle block diagram of the secondary circuit of the current transformer with bypass of the present invention;

[0031] Figure 3 It is a flow chart of the switching method of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0035] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] Example 1

[0037] like Figure 1-3 As shown, a power plant current transformer ratio adaptive switching system includes a current transformer secondary circuit with bypass, a signal acquisition and analysis module, a command decision module and a switch array. The current transformer secondary circuit with bypass is connected to the input end of the signal acquisition and analysis module to realize the electrical connection between the current transformer and the electric energy meter. The output end of the signal acquisition and analysis module is connected to the input end of the command decision module to collect the wire current and power data flowing in the secondary circuit of the current transformer with bypass, and obtain the direction and size of the power exchanged between the current customer metering point and the power grid. The command decision module is connected to the switch array to receive the current and power information returned by the signal acquisition and analysis module, analyze and calculate the current and power information, and convert the calculation results into action instructions and send them to the switch array.

[0038] Preferably, the secondary circuit of the current transformer with bypass includes a secondary winding of the current transformer, an array switch and a terminal block of a metering panel / metering cabinet. The secondary winding of the current transformer is connected to the array switch and the terminal block of the metering panel / metering cabinet through a wire, and the output end of the array switch is connected to the terminal block of the metering panel / metering cabinet through a wire.

[0039] Preferably, the signal acquisition and analysis module includes a micro power transformer / current transformer and a power direction relay. The front end is installed in a surrounding manner on the current conductor behind the lower terminal of the test junction box, and is used to measure the magnitude and direction of the current signal in the metering circuit at this time. The rear end is connected to the I / O interface of the instruction decision module by means of a signal line / wire. When used, the current magnitude and direction information can be transmitted to the instruction decision module for further analysis and decision-making.

[0040] The signal acquisition and analysis module uses the current transformer to identify and monitor the current and power data of the conductors flowing in the secondary circuit to obtain the direction and size of the power exchange between the current customer metering point and the power grid. Considering that in the secondary circuit wiring of the current transformer, the meter input wiring may not be able to guarantee the current path due to the ratio switching, the signal acquisition and analysis module should be installed on the meter output line that must be used in all secondary circuits of the current transformer.

[0041] Preferably, the switch array includes a light-emitting diode, a photosensor circuit, a signal line, a control line and a controlled switch. The controlled switch is connected in series with the light-emitting diode. When the controlled switch is turned on, current flows, and the light-emitting diode will emit a light signal. The light signal is sensed by the photosensor circuit, and the sensing result is sent to the instruction decision module via the signal line. The controlled switch is controlled by an external signal, and the signal comes from the signal line.

[0042] One end of the controlled switch of the switch array is connected to the lead-out line of the metering panel / metering cabinet terminal block, and the other end is connected to a corresponding current transformer secondary winding lead-out line. The photosensitive sensing circuit and the control line are connected to the I / O interface of the instruction decision module.

[0043] The switch array quickly and accurately executes the specified actions under the instructions sent by the instruction decision module, implements the switching of the secondary circuit wiring topology of the current transformer, and switches the secondary circuit incoming line actually connected to the electric energy meter to another one in the bypass. In order to ensure the effect and avoid short circuit before the meter, the switch array should be installed on a section of the loop line connected to the incoming current terminal of the electric energy meter. A switch is installed on each optional secondary circuit line and the on and off state of each switch is independent.

[0044] Preferably, the command decision module and the switch array are both installed on the out-of-meter line that is required to be used in each ratio secondary circuit of the current transformer.

[0045] Preferably, it also includes a state monitoring module, the input end of the state monitoring module is connected to the switch array, and the output end is connected to the instruction decision module. The state monitoring module is used to monitor the on and off state of each switch in the switch array and return the monitoring result to the instruction decision module.

[0046] The status monitoring module ensures the safety and reliability of the secondary circuit line switching process, because the secondary circuit of the current transformer needs to always ensure the integrity of the current circuit, otherwise an open circuit will cause serious safety risks, pose hidden dangers to personnel and equipment, and also cause measurement errors. In order to ensure the safety and stability of the current transformer ratio adaptive switching process throughout the process, on the one hand, the command decision module uses delayed instructions to ensure that the switch to be closed is actuated first, and the disconnection instruction of the switch to be disconnected can be sent after waiting for a period of time; on the other hand, an LED is set for each switch in the corresponding switch array to indicate its on and off status, and the status monitoring module implements monitoring and transmits the monitoring results back to the command decision module, so as to take corresponding measures in abnormal conditions.

[0047] Preferably, it also includes an abnormal warning module, and the input end of the abnormal warning module and the instruction decision module are connected by wireless communication. The wireless communication method includes Bluetooth / WiFi / 4G, which are all existing technologies and will not be described separately here. It is used to give warning information in the form of sound and light for the instructions sent by the instruction decision module, reminding the operation and maintenance personnel to come for investigation and processing.

[0048] Preferably, the abnormal warning module is installed in the metering screen cabinet.

[0049] The command decision module is mainly responsible for receiving, analyzing and judging the signal. Its functions are divided into two aspects: first, receiving the power and current information sent back by the signal acquisition and analysis module, and converting the calculation results into action instructions and sending them to the switch array; second, receiving the switch array on-off status sent back by the status monitoring module, and judging whether the current switch array indicator light signal is consistent with the instruction. In order to shorten the signal transmission distance, shorten the action delay time and reduce the risk of introducing deviations during the input and output signal transmission process, the command decision module should adopt a miniaturized design, and be installed in the form of a microcircuit based on a single-chip computing circuit, the signal acquisition and analysis module, and the switch array as a whole at the outgoing line position in the secondary circuit of the current transformer.

[0050] A method for adaptively switching the transformation ratio of a current transformer in a power plant comprises the following steps:

[0051] Step 1: Lay out and install the secondary circuit of the current transformer with bypass;

[0052] Step 2: The signal acquisition and analysis module collects the wire current and power data flowing in the secondary circuit of the current transformer through the current sensor and the power direction relay, and transmits the collected data to the command decision analysis module;

[0053] Step 3: The command decision analysis module determines and analyzes the current and power information uploaded by the signal acquisition analysis module, and determines whether the operation mode has changed;

[0054] Step 4: If the result of the judgment in step 3 is that the operation mode has not changed, then the process ends; otherwise, the command decision module analyzes and determines the applicable current transformer ratio, and the command decision module sends a closing command to the switch array according to the determined applicable current transformer ratio, and the switch array performs a closing operation;

[0055] Step 5: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful;

[0056] Step 6: If the switch array fails to perform the closing operation in step 5, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module ends after sending out an audible and visual warning message; otherwise, the instruction decision module sends a disconnection instruction to the switch array, and the switch array performs the disconnection operation;

[0057] Step 7: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful;

[0058] Step 8: If the result of step 7 is that the operation is successful, the process ends; otherwise, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module sends an audible and visual warning message and the process ends.

[0059] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for adaptively switching the ratio of current transformers in power plants. It is characterized in that The invention comprises a current transformer ratio adaptive switching system of a power plant, which comprises a secondary circuit of a current transformer with a bypass, a signal acquisition and analysis module, a command decision module, a switch array, a state monitoring module and an abnormal warning module. The secondary circuit of the current transformer with a bypass is connected to the input end of the signal acquisition and analysis module to realize the electrical connection between the current transformer and the electric energy meter. The output end of the signal acquisition and analysis module is connected to the input end of the command decision module to collect the current and power data of the conductor flowing in the secondary circuit of the current transformer with a bypass, and obtain the direction and magnitude of the power exchanged between the current customer metering point and the power grid. The command decision module is connected to the switch array to receive the current and power information returned by the signal acquisition and analysis module, analyze and calculate the current and power information, and convert the calculation results into action instructions and send them to the switch array; the output end of the state monitoring module is connected to the input end of the command decision module to return the state of the switch array to the command decision module; the output end of the command decision module is connected to the input end of the abnormal warning module to instruct the abnormal warning module, and the abnormal warning module ends after sending out an audible and visual warning information; When switching using this system, the following steps are included: Step 1: Lay out and install the secondary circuit of the current transformer with bypass; Step 2: The signal acquisition and analysis module collects the wire current and power data flowing in the secondary circuit of the current transformer through the current sensor and the power direction relay, and transmits the collected data to the command decision analysis module; Step 3: The command decision analysis module determines and analyzes the current and power information uploaded by the signal acquisition analysis module, and determines whether the operation mode has changed; Step 4: If the result of the judgment in step 3 is that the operation mode has not changed, then the process ends; otherwise, the command decision module analyzes and determines the applicable current transformer ratio, and the command decision module sends a closing command to the switch array according to the determined applicable current transformer ratio, and the switch array performs a closing operation; Step 5: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful; Step 6: If the switch array fails to perform the closing operation in step 5, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module ends after sending out an audible and visual warning message; otherwise, the instruction decision module sends a disconnection instruction to the switch array, and the switch array performs the disconnection operation; Step 7: The state monitoring module transmits the state of the switch array back to the command decision module, and the command decision module determines whether the closing operation of the switch array is successful; Step 8: If the result of step 7 is that the operation is successful, the process ends; otherwise, the instruction decision module sends an instruction to the abnormal warning module, and the abnormal warning module sends an audible and visual warning message and the process ends.

2. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that In the current transformer ratio adaptive switching system of a power plant, the secondary circuit of the current transformer with bypass includes a current transformer secondary winding, an array switch and a metering panel / metering cabinet terminal block. The current transformer secondary winding is connected to the array switch and the metering panel / metering cabinet terminal block through a wire, and the output end of the array switch is connected to the metering panel / metering cabinet terminal block through a wire.

3. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that In the adaptive switching system of current transformer ratio in power plants, the signal acquisition and analysis module includes a micro power transformer / current transformer and a power direction relay. The front end is installed in a surrounding manner on the current conductor behind the lower terminal of the test junction box to measure the size and direction of the current signal in the metering circuit at this time. The back end uses a signal line / cable to access the I / O interface of the command decision module.

4. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that In the adaptive switching system of current transformer ratio in power plants, the switch array includes a light-emitting diode, a photosensitive sensing circuit, a signal line, a control line and a controlled switch. The controlled switch is connected in series with the light-emitting diode. When the controlled switch is turned on, current flows, and the light-emitting diode will emit a light signal. The light signal is sensed by the photosensitive sensing circuit, and the sensing result is sent to the command decision module via the signal line.

5. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that In the adaptive switching system of current transformer ratio in power plants, the command decision module, signal acquisition and analysis module and switch array are all installed on the out-of-meter line that is required to be used in the secondary circuits of each ratio of the current transformer.

6. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that The power plant current transformer ratio adaptive switching system also includes a state monitoring module, the input end of the state monitoring module is connected to the switch array, and the output end is connected to the instruction decision module. The state monitoring module is used to monitor the on-off state of each switch in the switch array and return the monitoring result to the instruction decision module.

7. A method for adaptively switching the current transformer ratio of a power plant according to claim 1, It is characterized in that The power plant current transformer ratio adaptive switching system also includes an abnormal warning module, the input end of the abnormal warning module and the instruction decision module are connected by wireless communication, and is used to give warning information in the form of sound and light for the instructions sent by the instruction decision module.

8. A method for adaptively switching the current transformer ratio of a power plant according to claim 7, It is characterized in that In the adaptive switching system of current transformer ratio in power plants, the abnormal warning module is installed in the metering panel cabinet.

Images