A method for realizing overvoltage regulation in a low voltage circuit measurement and control terminal

Abstract

The present invention discloses a method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal. The method comprises the following steps: connecting the low-voltage circuit measurement and control terminal to the contactor control of the distributed power supply point of the low-voltage power grid, the data integration hub device of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device to obtain the time synchronization, after obtaining the time synchronization information, the local clock is synchronously updated and the "local time status mark" is recorded, and the low-voltage circuit measurement and control terminal analyzes and controls the contactor opening and closing according to the "local time status mark" signal and the distributed power supply point data, so as to timely respond to the overvoltage absorption. The gain effect of the present invention is that the present invention can realize the real-time monitoring of the power supply voltage in the low-voltage power grid area, the comprehensive regulation of the power supply voltage connected to the newly added power supply, and timely complete the absorption of the excess voltage, effectively solving the problem of overvoltage caused by the continuous connection of the newly added power supply to the low-voltage power grid, and ensuring the safety of the user's electricity use.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution and dispatching of power grid systems, and more specifically, to a method for implementing overvoltage regulation in a low-voltage loop measurement and control terminal. Background Art

[0002] The power system is an electric energy production and consumption system consisting of power generation, transmission, transformation, distribution and consumption. Its main function is to convert primary energy (such as coal, oil, natural gas, hydropower, wind power, solar energy, etc.) from nature into electric energy through power generation devices, and then transmit the electric energy to various users through transmission, transformation and distribution to meet people's demand for electric energy in production and life.

[0003] The power system includes transmission network and distribution network, among which the distribution network is mainly divided into high voltage network, medium voltage network and low voltage network.

[0004] The low-voltage power grid is the last link in the power system that connects users. It is responsible for converting medium-voltage power from substations into low-voltage power through step-down transformers and then distributing it to households, businesses, and industrial users, providing personalized power services for different types of users.

[0005] With the development of science and technology and the advancement of technology, the types of power supply points in low-voltage power grids are increasing, and the number of newly connected power supply points is also increasing, which effectively alleviates the power supply pressure of the power grid system.

[0006] However, since the newly added power sources of the low-voltage power grid (including energy storage power generation systems, distributed photovoltaic power generation systems, small wind power generation systems, etc.) are mainly connected to the low-voltage power grid by direct access, too many newly added power sources are connected to the substation for power supply, which will lead to overvoltage problems. If the output power consumption end cannot absorb the electric energy in time, it will easily cause the voltage of the low-voltage power grid to rise. If the power supply voltage exceeds the maximum operating voltage of the electrical equipment at the output power consumption end of the low-voltage power grid, it will cause the electrical equipment to overvoltage and burn, affecting the normal life of users and causing economic losses to users. In addition, there are safety hazards in electricity use, resulting in a bad electricity use experience.

[0007] At present, there are two main methods to deal with overvoltage caused by too many new power points in the low-voltage power grid:

[0008] 1) Choose a large-capacity transformer to replace the existing small-capacity transformer in the substation area. The larger the capacity of the replacement transformer, the smaller the internal resistance, and the stronger and more stable the external power supply capacity of the converted voltage. However, when the capacity of the distributed power supply is large, the low-voltage power grid will still have overvoltage problems, and the output capacity of the distributed power supply changes frequently and is difficult to predict, so it is impossible to fundamentally solve the current problems.

[0009] 2) Add a voltage stabilizer on the user side. The voltage stabilizer detects the voltage in real time through the voltage detection system. When an overvoltage occurs, the servo control system adjusts the internal coil ratio to stabilize the voltage. This method requires the user to install a voltage stabilizer. Currently, only users with strict requirements on voltage quality will invest in additional equipment. For ordinary users, the additional cost to solve the overvoltage problem increases the burden on users.

[0010] Although the above two methods can alleviate the problem of overvoltage caused by the access of new power supply points to the low-voltage power grid to a certain extent, the two methods still have great limitations in practical applications.

[0011] In view of this, there is an urgent need for a technical solution that can timely and safely complete the power supply regulation of the low-voltage power grid according to the actual power demand, so as to solve the problem of high absorption pressure of the power supply voltage after access caused by too many new power supply points in the current low-voltage power grid. Summary of the invention

[0012] The purpose of the present invention is to provide a method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal, which is used to solve the problem of high allocation and absorption pressure when connecting to power distribution applications due to too many new power supply points in the above-mentioned existing low-voltage power grid.

[0013] In order to achieve the above object, the present invention adopts the following technical solution:

[0014] A method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal comprises the following steps:

[0015] Step 1: Connect the low-voltage circuit measurement and control terminal to the contactor control of the distributed power source point of the low-voltage power grid. The contactor is set between the low-voltage power grid side and the distributed power source point. The low-voltage circuit measurement and control terminal is responsible for monitoring and obtaining data from each distributed power source point.

[0016] Step 2: The data integration hub device of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device to obtain time synchronization, so as to ensure the time consistency of data acquisition in the entire substation area, that is, the data acquisition time of all low-voltage circuit measurement and control terminals under the power supply range covered by the transformer is consistent, and after obtaining the synchronization information, the local clock is synchronously updated and the "local time status flag" is recorded.

[0017] The multiple low-voltage circuit measurement and control terminals in the low-voltage power grid can be connected to the main control system through a data transmission media device (RS485 communication bus module) with a data integration hub device. The data integration hub device serves as the main transmission hub device and communicates with each of the low-voltage circuit measurement and control terminals through polling, and completes data reading or sending control instructions in combination with the "local time status flag".

[0018] When the low-voltage circuit measurement and control terminal obtains the time synchronization information and automatically completes the update of the local clock, it records "local time status flag = credible".

[0019] When the low-voltage circuit measurement and control terminal fails to complete time acquisition or restart for more than 48 hours, it records "local time status flag = untrustworthy";

[0020] Step 3: The data transmission medium device is set to monitoring mode. In monitoring mode, the data transmission medium device monitors the broadcast data of the entire station area, including data such as time synchronization and freezing. The data transmission medium device does not connect to the data integration hub device side. The data transmission medium device automatically locks the data interaction working frequency band of the data integration hub device. The data transmission medium device selects broadcast instructions such as time synchronization and freezing and forwards them to the low-voltage circuit measurement and control terminal;

[0021] Step 4: When the "local time status flag = untrustworthy" recorded by the low-voltage circuit measurement and control terminal, and at the same time, the low-voltage circuit measurement and control terminal detects through the data transmission medium device that the voltage of any phase of the three-phase voltage of the distributed power supply point is greater than the preset overvoltage (235V), the contactor is controlled to open and disconnect from the low-voltage power grid according to the preset time delay of 2 seconds;

[0022] Step 5: The low-voltage circuit measurement and control terminal monitors the phase voltages of the distributed power source point through the data transmission medium device. When the phase voltages of the distributed power source point are continuously less than the safety voltage (230V) within a preset safety time, such as 10 minutes, the low-voltage circuit measurement and control terminal controls the contactor to close.

[0023] After controlling the contactor to close, the low-voltage circuit measurement and control terminal continues to monitor the power P and the actual voltage value U of each phase of the distributed power source point through the data transmission medium device;

[0024] Step 6: Setting and regulating self-recording, when the "local time status flag = credible" of the low-voltage circuit measurement and control terminal, in the preset integer time period (every 8-19 o'clock), the low-voltage circuit measurement and control terminal randomly generates an execution control time (1-10 minutes) based on the preset minute interval at the hour of each hour, executes and controls the contactor to open and close once, and the low-voltage circuit measurement and control terminal records the measured current and the measured voltage, obtains the change △I between the measured current and the set current, obtains the change △U between the measured voltage and the set voltage, and obtains the linear relationship between △U and △I;

[0025] Step 7: The low-voltage circuit measurement and control terminal obtains the actual voltage value U, and controls the contactor to perform opening and closing adjustment actions according to the change △U between the actual voltage value U and the set voltage value.

[0026] The actual voltage value U is obtained at the low-voltage circuit measurement and control terminal, and the change range of the actual voltage value U obtained by the low-voltage circuit measurement and control terminal and the set voltage value △U and the change range of △I of the distributed power supply point are within the preset stable value range,

[0027] The low-voltage circuit measurement and control terminal controls the contactor to open. When the distribution network is over-voltage, the number of power points needs to be adjusted. The adjustment is completed by monitoring and shutting down the power points. The total overvoltage needs to be adjusted according to the relationship between the change in the set voltage △U and the change in the set current △I, and then determine how many power points need to be shut down. Unnecessary power points will not be connected to the low-voltage circuit measurement and control terminal for group control, so as to achieve the purpose of timely, accurate and rapid regulation of overvoltage. When △U is 10V, the change range caused by the corresponding △I of the monitored distributed power point is ±20% of △U being 10V, that is, the capacity △I of the distributed power point is reduced, and the overvoltage caused by the change in the set voltage value △U is reduced, which can reduce the range of regulation of the regulation method.

[0028] The number of power supply points P in the power grid is obtained, and the total overvoltage amount is used to control and adjust the number of power supply points P in the power grid using the relationship between △U and △I.

[0029] The relationship between ΔU and ΔI is as follows:

[0030] Using the node voltage method, we can get u d (s) The expression of u d (s) Performing an inverse Laplace transform, we get u d (t) The expression is as follows:

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] in, u d (t)It consists of two monotonically decaying components, two underdamped oscillating components and two steady-state components. and are the monotonic decay components with small slow variation and large fast variation, respectively. and is the underdamped oscillation component, oh is the voltage angular frequency, e d is the grid voltage, R g is the line resistance, K p is the current loop proportionality coefficient, K i is the current loop integral coefficient, L 1 is the inverter filter inductor, synchronously rotating coordinate system d The axis and terminal voltage vectors coincide, i d for d The shaft current component is the active current, Yes is the change between the measured current and the set current, e Is a constant.

[0039] If the sum of the actual voltage value U obtained by the low-voltage circuit measurement and control terminal and the set value change △U of the distributed power supply point is less than the preset overvoltage setting value (235V), the low-voltage circuit measurement and control terminal controls the contactor to close;

[0040] Step 8: When the number of closing-opening-closing cycles of the contactor exceeds the preset number of cycles (20 times) within a continuous time period (24 consecutive hours), after the contactor is opened, the contactor is controlled not to close again until the voltage of each phase of the monitored distributed power supply point obtained by the low-voltage circuit measurement and control terminal is less than the preset safety voltage of 230V, and the contactor enters the next cycle counting period.

[0041] Step 9: When the total number of cycles recorded for the contactor exceeds the preset number of opening and closing cycles, the contactor is controlled to keep the contactor closed and a device replacement warning signal is issued to prompt the operator to replace the contactor in time to ensure the stability and safety of overvoltage control.

[0042] Preferably, the data integration hub device is a receiving concentrator or a gateway, and the data transmission medium device is a carrier module or an RS485 communication bus module.

[0043] Preferably, in step 3, in the monitoring mode, the data transmission medium device does not actively send network access messages and maintains the monitoring state. Responsible for monitoring the broadcast data of the entire area, including data such as time synchronization and freezing. Time synchronization data: In the low-voltage power grid, time synchronization refers to the synchronization and calibration of the clocks of the electric energy meters and related equipment in the entire area. Freeze data: Freezing refers to the fixed storage of certain data of the electric energy meter at a specific time point or under certain conditions.

[0044] Preferably, in step 4, the preset overvoltage is set to 235V, and the preset time is set to a 2-second delay.

[0045] Preferably, in step 5, the preset safety time is set to 10 minutes, the safety voltage is set to 230V, and if the power P of each phase of the distributed power supply point is monitored by the low-voltage circuit measurement and control terminal to be less than 1000W, no regulation is performed to keep the contactor in the closed state.

[0046] Preferably, in step 6, the preset integer time period is set to 8-19 o'clock every day, and the preset minute interval is set to 1-10 minutes.

[0047] Preferably, in step 7, the preset overvoltage setting value is set to 235V.

[0048] Preferably, in step 8, the continuous time period is set to 24 hours, the preset number of periodic cycles is set to 20 times, and the preset safety voltage is set to 230V.

[0049] Preferably, the preset number of opening and closing cycles in step 9 is 30,000 to 50,000 times, and the number of opening and closing cycles is recorded as 1 opening and closing cycle according to the closing-opening-closing action of the contactor. In order to better ensure the stable operation of the monitoring system of the low-voltage power grid, a lower preset number of opening and closing cycles, such as 30,000 times, can be selected to avoid the problem of premature aging of the contacts of some contactors due to burning after the opening and closing actions, ensure the accuracy of obtaining and recording the number of opening and closing cycles, and maintain the efficiency of monitoring and control of the low-voltage power grid overvoltage monitoring and control system.

[0050] Preferably, the low-voltage circuit measurement and control terminal is provided with a manual prohibition control operation port for implementing the overvoltage regulation method, and the manual prohibition control operation port is connected to the contactor of the distributed access point. The configurable manual prohibition control operation port for accessing the secure distributed power source point prohibits the system from performing comprehensive control to maintain the access stability of the secure distributed power source point.

[0051] Compared with the prior art, the present invention has the following advantages:

[0052] The present invention provides an overvoltage regulation method in a low-voltage circuit measurement and control terminal, thereby realizing real-time monitoring of the power supply voltage in the low-voltage power grid area, comprehensive regulation of the power supply voltage of the newly added power supply, and timely absorption of excess voltage, effectively solving the problem of overvoltage caused by the continuous connection of new power supplies to the low-voltage power grid, and ensuring the safety of users' electricity use.

[0053] By implementing the overvoltage regulation method in the low-voltage circuit measurement and control terminal provided by the present invention, there is no need to replace the transformer or other equipment of the low-voltage power grid, thus reducing production costs, and the connection is convenient and the regulation efficiency is high.

[0054] This patent realizes the rigid regulation method of overvoltage regulation method in the low-voltage circuit measurement and control terminal, that is, timely regulating the grid voltage in a nonlinear manner by cutting off the power supply point, so that the grid voltage in the substation area is guaranteed to be in a safe and effective area.

[0055] The overvoltage regulation method implemented in the low-voltage circuit measurement and control terminal provided by the present invention does not rely on daily strategy formulation and information collection of concentrators or gateways. It can automatically adjust the overvoltage by simply listening to the broadcast time of the existing acquisition system. It is not necessary to upload all data to the system platform. The main control system performs comprehensive management and control. The low-voltage circuit measurement and control terminal and the contactor are used to cooperate in the joint control to achieve automatic overvoltage control of distributed power supply points in the low-voltage power grid, thereby ensuring the power supply and electricity safety of the entire low-voltage power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of an overvoltage regulation method implemented in a low-voltage circuit measurement and control terminal provided by the present invention.

[0057] Figure 2 It is a linear schematic diagram of △U and △I of a power supply point of a low-voltage power grid for implementing an overvoltage regulation method in a low-voltage circuit measurement and control terminal provided by the present invention. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0059] In order to make the purpose, technical solution 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 used to limit the present invention.

[0060] Specifically, the present invention is a method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal, comprising the following steps:

[0061] Step 1: Connect the low-voltage circuit measurement and control terminal to the contactor control of the distributed power source point of the low-voltage power grid. The contactor is set between the low-voltage power grid side and the distributed power source point. The low-voltage circuit measurement and control terminal is responsible for monitoring and obtaining data from each distributed power source point.

[0062] Step 2: The data integration hub device of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device to obtain time synchronization, so as to ensure the time consistency of data acquisition in the entire substation area, that is, the data acquisition time of all low-voltage circuit measurement and control terminals under the power supply range covered by the transformer is consistent, and after obtaining the synchronization information, the local clock is synchronously updated and the "local time status flag" is recorded.

[0063] The multiple low-voltage circuit measurement and control terminals in the low-voltage power grid can be connected to the main control system through a data transmission media device (RS485 communication bus module) with a data integration hub device. The data integration hub device serves as the main transmission hub device and communicates with each of the low-voltage circuit measurement and control terminals through polling, and completes data reading or sending control instructions in combination with the "local time status flag".

[0064] When the low-voltage circuit measurement and control terminal obtains the time synchronization information and automatically completes the update of the local clock, it records "local time status flag = credible".

[0065] When the low-voltage circuit measurement and control terminal fails to complete time acquisition or restart for more than 48 hours, it records "local time status flag = untrustworthy";

[0066] Step 3: The data transmission medium device is set to monitoring mode. In monitoring mode, the data transmission medium device monitors the broadcast data of the entire station area, including data such as time synchronization and freezing. The data transmission medium device does not connect to the data integration hub device side. The data transmission medium device automatically locks the data interaction working frequency band of the data integration hub device. The data transmission medium device selects broadcast instructions such as time synchronization and freezing and forwards them to the low-voltage circuit measurement and control terminal;

[0067] Step 4: When the "local time status flag = untrustworthy" recorded by the low-voltage circuit measurement and control terminal, and at the same time, the low-voltage circuit measurement and control terminal detects through the data transmission medium device that the voltage of any phase of the three-phase voltage of the distributed power supply point is greater than the preset overvoltage (235V), the contactor is controlled to open and disconnect from the low-voltage power grid according to the preset time delay of 2 seconds;

[0068] Step 5: The low-voltage circuit measurement and control terminal monitors the phase voltages of the distributed power source point through the data transmission medium device. When the phase voltages of the distributed power source point are continuously less than the safety voltage (230V) within a preset safety time, such as 10 minutes, the low-voltage circuit measurement and control terminal controls the contactor to close.

[0069] After controlling the contactor to close, the low-voltage circuit measurement and control terminal continues to monitor the power P and the actual voltage value U of each phase of the distributed power source point through the data transmission medium device;

[0070] Step 6: Setting and regulating self-recording, when the "local time status flag = credible" of the low-voltage circuit measurement and control terminal, in the preset integer time period (every 8-19 o'clock), the low-voltage circuit measurement and control terminal randomly generates an execution control time (1-10 minutes) based on the preset minute interval at the hour of each hour, executes and controls the contactor to open and close once, and the low-voltage circuit measurement and control terminal records the measured current and the measured voltage, obtains the change △I between the measured current and the set current, obtains the change △U between the measured voltage and the set voltage, and obtains the linear relationship between △U and △I;

[0071] Step 7: The low-voltage circuit measurement and control terminal obtains the actual voltage value U, and controls the contactor to perform opening and closing adjustment actions according to the change △U between the actual voltage value U and the set voltage value.

[0072] The actual voltage value U is obtained at the low-voltage circuit measurement and control terminal, and the change range of the actual voltage value U obtained by the low-voltage circuit measurement and control terminal and the set voltage value △U and the change range of △I of the distributed power supply point are within the preset stable value range,

[0073] The low-voltage circuit measurement and control terminal controls the contactor to open. When the distribution network is over-voltage, the number of power points needs to be adjusted. The adjustment is completed by monitoring and shutting down the power points. The total overvoltage needs to be adjusted according to the relationship between the change in the set voltage △U and the change in the set current △I, and then determine how many power points need to be shut down. Unnecessary power points will not be connected to the low-voltage circuit measurement and control terminal for group control, so as to achieve the purpose of timely, accurate and rapid regulation of overvoltage. When △U is 10V, the change range caused by the corresponding △I of the monitored distributed power point is ±20% of △U being 10V, that is, the capacity △I of the distributed power point is reduced, and the overvoltage caused by the change in the set voltage value △U is reduced, which can reduce the range of regulation of the regulation method.

[0074] The number of power supply points P in the power grid is obtained, and the total overvoltage amount is used to control and adjust the number of power supply points P in the power grid using the relationship between △U and △I.

[0075] The relationship between ΔU and ΔI is as follows:

[0076] Using the node voltage method combined with the inverse Laplace transform, we get u d (t) The expression is as follows:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] in, u d (t) It consists of two monotonically decaying components, two underdamped oscillating components and two steady-state components. and are the monotonic decay components with small slow variation and large fast variation, respectively. and is the underdamped oscillation component, oh is the voltage angular frequency, e d is the grid voltage, R g is the line resistance, K p is the current loop proportionality coefficient, K i is the current loop integral coefficient, L 1 is the inverter filter inductor, synchronously rotating coordinate system d The axis and terminal voltage vectors coincide, i d for d The shaft current component is the active current, Yes is the change between the measured current and the set current, e Is a constant.

[0085] If the sum of the actual voltage value U obtained by the low-voltage circuit measurement and control terminal and the set value change △U of the distributed power supply point is less than the preset overvoltage setting value (235V), the low-voltage circuit measurement and control terminal controls the contactor to close;

[0086] Step 8: When the number of closing-opening-closing cycles of the contactor exceeds the preset number of cycles (20 times) within a continuous time period (24 consecutive hours), after the contactor is opened, the contactor is controlled not to close again until the voltage of each phase of the monitored distributed power supply point obtained by the low-voltage circuit measurement and control terminal is less than the preset safety voltage of 230V, and the contactor enters the next cycle counting period.

[0087] Step 9: When the total number of cycles recorded for the contactor exceeds the preset number of opening and closing cycles, the contactor is controlled to keep the contactor closed and a device replacement warning signal is issued to prompt the operator to replace the contactor in time to ensure the stability and safety of overvoltage control.

[0088] Preferably, the data integration hub device is a receiving concentrator or a gateway, and the data transmission medium device is a carrier module or an RS485 communication bus module.

[0089] Preferably, in step 3, in the monitoring mode, the data transmission medium device does not actively send network access messages and maintains the monitoring state. Responsible for monitoring the broadcast data of the entire area, including data such as time synchronization and freezing. Time synchronization data: In the low-voltage power grid, time synchronization refers to the synchronization and calibration of the clocks of the electric energy meters and related equipment in the entire area. Freeze data: Freezing refers to the fixed storage of certain data of the electric energy meter at a specific time point or under certain conditions.

[0090] Preferably, in step 4, the preset overvoltage is set to 235V, and the preset time is set to a 2-second delay.

[0091] Preferably, in step 5, the preset safety time is set to 10 minutes, the safety voltage is set to 230V, and if the power P of each phase of the distributed power supply point is monitored by the low-voltage circuit measurement and control terminal to be less than 1000W, no regulation is performed to keep the contactor in the closed state.

[0092] Preferably, in step 6, the preset integer time period is set to 8-19 o'clock every day, and the preset minute interval is set to 1-10 minutes.

[0093] Preferably, in step 7, the preset overvoltage setting value is set to 235V.

[0094] Preferably, in step 8, the continuous time period is set to 24 hours, the preset number of periodic cycles is set to 20 times, and the preset safety voltage is set to 230V.

[0095] Preferably, the preset number of opening and closing cycles in step 9 is 30,000 to 50,000 times, and the number of opening and closing cycles is recorded as 1 opening and closing cycle according to the closing-opening-closing action of the contactor. In order to better ensure the stable operation of the monitoring system of the low-voltage power grid, a lower preset number of opening and closing cycles, such as 30,000 times, can be selected to avoid the problem of premature aging of the contacts of some contactors due to burning after the opening and closing actions, ensure the accuracy of obtaining and recording the number of opening and closing cycles, and maintain the efficiency of monitoring and control of the low-voltage power grid overvoltage monitoring and control system.

[0096] Preferably, the low-voltage circuit measurement and control terminal is provided with a manual prohibition control operation port for implementing the overvoltage regulation method, and the manual prohibition control operation port is connected to the contactor of the distributed access point. The configurable manual prohibition control operation port for accessing the secure distributed power source point prohibits the system from performing comprehensive control to maintain the access stability of the secure distributed power source point.

[0097] First embodiment:

[0098] The low-voltage circuit measurement and control terminal itself has the function of real-time collection of current and voltage data. By combining the low-voltage circuit measurement and control terminal with the contactor, real-time monitoring of new power supply points in the low-voltage power grid can be realized, and coordinated operation control of distributed power generation and the power grid can be achieved. The adverse effects of overvoltage on the operation of the power grid caused by the access of too many distributed power supply points can be avoided to the greatest extent, thereby improving the low-voltage power grid system's ability to absorb the access of new energy such as distributed photovoltaics.

[0099] Since the current power supply overvoltage problem is basically caused by too many newly added distributed power supply points and lack of timely and effective regulation of the newly added distributed power supply points, the present invention gradually cuts off the distributed power supply points from the perspective of overall layout regulation by controlling the opening and closing joint control of the distributed power supply points through contactors, and controls the number of newly added distributed power supply points while ensuring stable power supply. The purpose of ensuring voltage absorption and the output voltage of the newly added power supply points is achieved to achieve the purpose of controlling the overvoltage amplitude of the power supply voltage, thereby solving the problem of overvoltage in the low-voltage power grid caused by too many newly added power supply points and being unable to accurately regulate the number of access points.

[0100] This embodiment provides a method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal:

[0101] Step 1: Connect the low-voltage circuit measurement and control terminal to the contactor control of the distributed power source point of the low-voltage power grid. The contactor is set between the low-voltage power grid side and the distributed power source point. The low-voltage circuit measurement and control terminal is responsible for monitoring and obtaining data from each distributed power source point.

[0102] Step 2: The data integration hub device (receiving concentrator) of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device (RS485 communication bus module) to obtain the time synchronization information. After obtaining the time synchronization information, the local clock is synchronously updated and the "local time status flag" is recorded. In the monitoring mode, the RS485 communication bus module can monitor and analyze the communication data on the bus. It can capture all data frames transmitted on the bus and parse them to understand the communication status between various devices.

[0103] Among them, when the low-voltage circuit measurement and control terminal obtains the time synchronization information and automatically completes the update of the local clock, it records "local time status flag = credible".

[0104] If the low-voltage circuit measurement and control terminal fails to complete time acquisition or restart for more than 48 hours, "local time status flag = untrustworthy" will be recorded;

[0105] Step 3: The data transmission medium device is set to monitoring mode. In monitoring mode, the data transmission medium device monitors the broadcast data of the entire station area, including data such as time synchronization and freezing.

[0106] The RS485 communication bus module does not connect to the data integration hub equipment side. The RS485 communication bus module automatically locks the data interaction working frequency band of the receiving concentrator, and selects broadcast instructions such as synchronization and freezing and forwards them to the low-voltage circuit measurement and control terminal;

[0107] Step 4: When the "local time status flag = untrustworthy" recorded by the low-voltage circuit measurement and control terminal, and the voltage of any phase of the three-phase voltage of the distributed power supply point detected by the low-voltage circuit measurement and control terminal through the data transmission medium device is greater than 235V, the contactor is controlled to open and disconnect from the low-voltage grid after a delay of 2 seconds;

[0108] Step 5: The low-voltage circuit measurement and control terminal monitors the phase voltages of the distributed power source through the data transmission medium device. When the phase voltages of the distributed power source are continuously less than 230V for 10 minutes, the low-voltage circuit measurement and control terminal controls the contactor to close.

[0109] After the control contactor is closed, the low-voltage circuit measurement and control terminal continues to monitor the power P and actual voltage value U of each phase of the distributed power source point through the data transmission medium device;

[0110] Wherein, when the power P of each phase of the distributed power source point is monitored by the low-voltage circuit measurement and control terminal to be less than 1000W, no regulation is performed to keep the contactor in the closed state;

[0111] Step 6: Setting and controlling self-recording. When the "local time status flag = credible" of the low-voltage circuit measurement and control terminal is set at 8-19 o'clock every day, the low-voltage circuit measurement and control terminal randomly generates the execution control time based on 1-10 minutes at the hour of each hour, executes the control contactor opening and closing operation, and the low-voltage circuit measurement and control terminal records the measured current and the measured voltage, obtains the change △I between the measured current and the set current, obtains the change △U between the measured voltage and the set voltage, and obtains the linear relationship between △U and △I;

[0112] Step 7: The low-voltage circuit measurement and control terminal obtains the actual voltage value U, and controls the contactor to perform opening and closing adjustment actions according to the change △U between the actual voltage value U and the set voltage value. The actual voltage value U is obtained at the low-voltage circuit measurement and control terminal. The change range of the actual voltage value U and the set voltage value obtained by the low-voltage circuit measurement and control terminal and the △I of the distributed power source point are within the preset stable value range. When △U is 10V, the change range caused by the corresponding △I of the monitored distributed power source point is ±20% of △U being 10V, that is, the capacity △I of the distributed power source point is reduced, and the overvoltage caused by the change △U of the set voltage value is reduced, which can reduce the range of regulation of the regulation method. Then the low-voltage circuit measurement and control terminal controls the contactor to open.

[0113] If the sum of the actual voltage value U obtained at the low-voltage circuit measurement and control terminal and the set value change △U of the distributed power supply point is less than 235V, the low-voltage circuit measurement and control terminal controls the contactor to close;

[0114] Step 8: When the number of closing-opening-closing cycles of the contactor exceeds 20 times within 24 consecutive hours, the contactor will be controlled not to close after opening until the low-voltage circuit measurement and control terminal obtains that the voltage of each phase of the monitored distributed power source point is less than 230V, and the contactor enters the next cycle counting period.

[0115] Step 9: When the total number of contactor cycles recorded exceeds 50,000 times, the control contactor keeps the contactor closed and sends a warning signal for replacing the equipment, prompting the operator to replace the contactor in time.

[0116] Second embodiment:

[0117] This embodiment is similar to the first embodiment, except that an overvoltage regulation method is implemented in a low-voltage circuit measurement and control terminal provided in this embodiment:

[0118] Step 1: Connect the low-voltage circuit measurement and control terminal to the contactor control of the distributed power source point of the low-voltage power grid. The contactor is set between the low-voltage power grid side and the distributed power source point. The low-voltage circuit measurement and control terminal is responsible for monitoring and obtaining data from each distributed power source point.

[0119] Step 2: The data integration hub device (gateway) of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device (carrier module) to obtain the time synchronization information. After obtaining the time synchronization information, the local clock is updated synchronously and the "local time status flag" is recorded. The gateway includes the following functions: protocol conversion, data aggregation and forwarding, network management, security protection, support for remote control and management. The gateway can collect data from these different terminals and forward them to the main control system after aggregation. The operation status of the terminal can be remotely monitored through the gateway, and faults can be discovered and processed in time. Users can remotely control and manage the low-voltage circuit measurement and control terminal without on-site operation, which is particularly important for low-voltage power distribution systems distributed in different locations, and can improve the convenience and efficiency of management. In the monitoring mode, the carrier module will focus more on the monitoring and analysis of communication signals. It not only receives and sends data, but also monitors the strength, quality, interference, etc. of the carrier signal in real time.

[0120] Among them, when the low-voltage circuit measurement and control terminal obtains the time synchronization information and automatically completes the update of the local clock, it records "local time status flag = credible".

[0121] If the low-voltage circuit measurement and control terminal fails to complete time acquisition or restart for more than 48 hours, "local time status flag = untrustworthy" will be recorded;

[0122] Step 3: The data transmission medium device is set to monitoring mode. In monitoring mode, the data transmission medium device monitors the broadcast data of the entire station area, including data such as time synchronization and freezing.

[0123] The carrier module does not access the data integration hub equipment side. The carrier module automatically locks the data interaction working frequency band obtained by the gateway, and selects broadcast instructions such as synchronization and freezing to forward to the low-voltage circuit measurement and control terminal;

[0124] Step 4: When the "local time status flag = untrustworthy" recorded by the low-voltage circuit measurement and control terminal, and the voltage of any phase of the three-phase voltage of the distributed power supply point detected by the low-voltage circuit measurement and control terminal through the data transmission medium device is greater than 235V, the contactor is controlled to open and disconnect from the low-voltage grid after a delay of 2 seconds;

[0125] Step 5: The low-voltage circuit measurement and control terminal monitors the phase voltages of the distributed power source through the data transmission medium device. When the phase voltages of the distributed power source are continuously less than 230V for 10 minutes, the low-voltage circuit measurement and control terminal controls the contactor to close.

[0126] After the control contactor is closed, the low-voltage circuit measurement and control terminal continues to monitor the power P of each phase and the actual voltage value U of the distributed power source point through the data transmission medium device. If the power P of each phase of the distributed power source point monitored by the low-voltage circuit measurement and control terminal is less than 1000W, no regulation is performed to keep the contactor in the closed state;

[0127] Step 6: Setting and controlling self-recording. When the "local time status flag = credible" of the low-voltage circuit measurement and control terminal is set at 8-19 o'clock every day, the low-voltage circuit measurement and control terminal randomly generates the execution control time based on 1-10 minutes at the hour of each hour, executes the control contactor opening and closing operation, and the low-voltage circuit measurement and control terminal records the measured current and the measured voltage, obtains the change △I between the measured current and the set current, obtains the change △U between the measured voltage and the set voltage, and obtains the linear relationship between △U and △I;

[0128] Step 7: The low-voltage circuit measurement and control terminal obtains the actual voltage value U, and controls the contactor to perform opening and closing adjustment actions according to the change △U between the actual voltage value U and the set voltage value. The actual voltage value U is obtained at the low-voltage circuit measurement and control terminal. If the change amplitude of the actual voltage value U and the set voltage value obtained by the low-voltage circuit measurement and control terminal and the △I of the distributed power source point are within the preset stable value range, the low-voltage circuit measurement and control terminal controls the contactor to open. If the sum of the actual voltage value U and the set value change △U of the distributed power source point obtained at the low-voltage circuit measurement and control terminal is less than 235V, the low-voltage circuit measurement and control terminal controls the contactor to close.

[0129] Step 8: When the number of closing-opening-closing cycles of the contactor exceeds 20 times within 24 consecutive hours, the contactor will be controlled not to close after opening until the low-voltage circuit measurement and control terminal obtains that the voltage of each phase of the monitored distributed power source point is less than 230V, and the contactor enters the next cycle counting period.

[0130] Step 9: When the total number of contactor cycles recorded exceeds 30,000 times, the control contactor keeps the contactor closed and sends a warning signal for replacing the equipment, prompting the operator to replace the contactor in time.

[0131] Furthermore, in this embodiment, a manual prohibition control operation port is also provided, and the manual prohibition control operation port is connected to the contactor of the distributed access point. A manual prohibition control operation port is added to the secure distributed power supply point to maintain a stable connection between the secure distributed power supply point and the low-voltage power grid, thereby preventing the secure distributed power supply point from being disconnected due to comprehensive control, thereby affecting the stable operation of the low-voltage power grid that meets daily needs.

[0132] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. 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 claims of the present invention.

Claims

1. A method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal, characterized in that: The following steps are involved: Step 1: Connect the low-voltage circuit measurement and control terminal to the contactor of the distributed power source point of the low-voltage power grid, where the contactor is arranged between the low-voltage power grid side and the distributed power source point; Step 2: The data integration hub device of the low-voltage circuit measurement and control terminal communicates with the main control system through the data transmission medium device to obtain the time synchronization information, and after obtaining the time synchronization information, the local clock is synchronously updated and the "local time status flag" is recorded. When the low-voltage circuit measurement and control terminal obtains the time synchronization information and automatically completes the update of the local clock, it records "local time status flag = credible", When the low-voltage circuit measurement and control terminal fails to complete time acquisition or restart for more than 48 hours, "local time status flag = untrustworthy" is recorded; Step 3: The data transmission medium device is set to a monitoring mode. In the monitoring mode, the data transmission medium device monitors the broadcast data of the entire area. The data transmission medium device does not access the data integration hub device. The data transmission medium device automatically locks the data interaction working frequency band of the data integration hub device. The data transmission medium device screens the broadcast instructions and forwards them to the low-voltage circuit measurement and control terminal. Step 4: When the "local time status flag = untrustworthy" recorded by the low-voltage circuit measurement and control terminal, and at the same time, the low-voltage circuit measurement and control terminal detects through the data transmission medium device that the voltage of any phase of the three-phase voltage of the distributed power supply point is greater than the preset overvoltage, the contactor is controlled to open according to the preset time delay; Step 5: The low-voltage circuit measurement and control terminal monitors the phase voltages of the distributed power source point through the data transmission medium device. When the phase voltages of the distributed power source point are continuously less than the safety voltage within a preset safety time, the low-voltage circuit measurement and control terminal controls the contactor to close. After controlling the contactor to close, the low-voltage circuit measurement and control terminal continues to monitor the power P and the actual voltage value U of each phase of the distributed power source point through the data transmission medium device; Step 6: Setting and regulating self-recording. When the "local time status flag = credible" of the low-voltage circuit measurement and control terminal, the low-voltage circuit measurement and control terminal randomly generates an execution control time based on a preset minute interval at the hour of each hour in a preset integer time period, and executes a control operation of the contactor opening and closing. The low-voltage circuit measurement and control terminal records the measured current and the measured voltage, obtains the change △I between the measured current and the set current, obtains the change △U between the measured voltage and the set voltage, and obtains the linear relationship between △U and △I; Step 7: The low-voltage circuit measurement and control terminal obtains the actual voltage value U, and controls the contactor to perform opening and closing adjustment actions according to the change △U between the actual voltage value U and the set voltage value. The actual voltage value U is obtained at the low-voltage circuit measurement and control terminal, and the change amount △U between the actual voltage value U and the set voltage value obtained by the low-voltage circuit measurement and control terminal and the change amplitude of △I of the distributed power supply point are within the preset stable value range, then the low-voltage circuit measurement and control terminal controls the contactor to open; If the sum of the actual voltage value U obtained by the low-voltage circuit measurement and control terminal and the set value change △U of the distributed power source point is less than the preset overvoltage setting value, the low-voltage circuit measurement and control terminal controls the contactor to close; Step 8: When the number of closing-opening-closing cycles of the contactor exceeds the preset number of cycles in a continuous time period, after the contactor is opened, the contactor is controlled not to close again until the voltage of each phase of the distributed power source point monitored by the low-voltage circuit measurement and control terminal is less than the preset safety voltage, and the contactor enters the next cycle counting period; Step 9: When the total number of cycles of the contactor recorded exceeds the preset number of opening and closing cycles, the contactor is controlled to keep the contactor closed and a warning signal for replacing the equipment is issued.

2. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1 is characterized in that: The data integration hub device is a receiving concentrator or a gateway, and the data transmission medium device is a carrier module or an RS485 communication bus module.

3. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1 is characterized in that: In step 3, in the monitoring mode, the data transmission medium device does not actively send a network access message and maintains a monitoring state.

4. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: In step 4, the preset overvoltage is set to 235V, and the preset time is set to a 2-second delay.

5. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: In step 5, the preset safety time is set to 10 minutes, the safety voltage is set to 230V, and when the power P of each phase of the distributed power source point is monitored by the low-voltage circuit measurement and control terminal to be less than 1000W, no regulation is performed to keep the contactor in the closed state.

6. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: In step 6, the preset integer time period is set to 8-19 o'clock every day, and the preset minute interval is set to 1-10 minutes.

7. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: In step 7, the preset overvoltage setting value is set to 235V.

8. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: In step 8, the continuous time period is set to 24 hours, the preset number of cycle times is set to 20 times, and the preset safety voltage is set to 230V.

9. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: The preset number of opening and closing cycles in step 9 is 30,000 to 50,000 times, and the number of opening and closing cycles is recorded as one opening and closing cycle according to the closing-opening-closing action of the contactor.

10. The method for implementing overvoltage regulation in a low-voltage circuit measurement and control terminal according to claim 1, characterized in that: The low-voltage circuit measurement and control terminal is provided with a manual prohibition control operation port for implementing the overvoltage regulation method, and the manual prohibition control operation port is connected to the contactor of the distributed access point.

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