A Reactive Power Compensation System and Method Based on Cyclic Switching

Abstract

The present invention discloses a reactive power compensation system and method based on cyclic switching, belonging to the technical field of reactive power compensation. The system of the present invention includes: a master controller and a slave controller; the master controller is used to set the working mode. When the number of compensation branches of the power supply system is less than or equal to 16, the working mode is set to the independent working mode. In the independent working mode, the master controller controls the cyclic switching of the capacitor banks of the compensation branches. When the number of compensation branches of the power supply system is greater than 16, the working mode is set to the master-slave working mode. In the master-slave working mode, the master controller and the slave controller control the cyclic switching of the capacitor banks of the compensation branches through an expandable IO port based on serial communication. The present invention effectively improves the working efficiency and reduces the labor cost.

Description

Technical Field

[0001] The present invention relates to the technical field of reactive power compensation, and more specifically, to a reactive power compensation system and method based on cyclic switching. Background Art

[0002] The reactive power compensation power factor controller generally has 16 digital output ports. When the number of compensation branches is greater than 16, an extended IO output port scheme is usually adopted. For example, an IO port expansion module is used. The main controller samples signals, calculates and controls physical quantities, and uses serial communication to notify the expansion module to output IO combinations.

[0003] The expansion module is generally placed near the switch in the distribution cabinet, and it is not easy to observe the switching status indicator. To view the switching status through the controller on the cabinet door, the controller needs to specifically design a UI interface to display the switching status of the extended IO ports. Usually, electrical engineers will design switching indicators for the compensation branches on the cabinet door.

[0004] However, the situation where the number of compensation branches exceeds 16 is not common. Therefore, an external IO port expansion module needs to be purchased, which also brings new problems of adjustment interface or communication protocol compatibility, and may face the problem of secondary development of controller functions. Therefore, while wasting manpower and material resources, it cannot effectively solve the reactive power compensation problem when the number of compensation branches exceeds 16. If the above problems are solved, the input cost will increase and the efficiency will be low. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a reactive power compensation system based on cyclic switching, including: a main controller and a slave controller;

[0006] The main controller is used to set the working mode. When the number of compensation branches in the power supply system is less than or equal to 16, the working mode is set to the independent working mode. In the independent working mode, the main controller controls the cyclic switching of the capacitor banks of the compensation branches. When the number of compensation branches in the power supply system is greater than 16, the working mode is set to the master-slave working mode. In the master-slave working mode, the main controller and the slave controller control the cyclic switching of the capacitor banks of the compensation branches through the expandable IO ports of serial communication;

[0007] The main controller is used to set the capacitor capacity parameters of the main body and the slave controller. The set parameters include three groups of common compensation capacities of small, medium, and large, and each group of capacity corresponds to the port numbers of the main machine or the slave controller. Equal-capacity capacitors are used for cyclic switching.

[0008] Optionally, the main controller and the slave controller are connected through a serial communication port;

[0009] The communication mode of the serial communication port includes: RS485 communication mode.

[0010] Optionally, the main controller controls the cyclic switching of the capacitor bank of the compensation branch, including:

[0011] The main controller samples the electrical signals of the power supply system, calculates the parameter values of the power supply system based on the sampled electrical signals, determines the state quantity of the switching state switch of the compensation branch of the power supply system, and selects a cyclic switching method according to the parameter values and the state quantity;

[0012] If the cyclic switching method is selected, then according to the parameter values, the state quantity, and the cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups, the optimal switching scheme of the conventional switching method in the independent working mode is determined;

[0013] The preset cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups is specifically as follows:

[0014] For the input of cyclic switching:

[0015] When the large group capacitor bank in the reactive power demand compensation capacity lacking in the power supply system is sufficient for input, the large group capacitor bank is preferentially input;

[0016] After the reactive power demand of the power supply system changes and the large group capacitor bank cannot be input and the medium group capacitor bank is sufficient for input, it is judged whether there are uninput capacitors in the large group. If not, the medium group capacitor bank is directly input. If there are, it is further judged whether there are already input medium group capacitors. If not, the medium group capacitor bank is directly input. If there are, one group of the medium group is cut off and one path of the large group is input. If the medium group capacitor bank cannot be input and the small group capacitor bank is sufficient for input, it is judged whether there are uninput capacitors in the medium group. If not, the small group capacitor bank is directly input. If there are, it is further judged whether there are already input small groups. If not, the small group capacitor bank is directly input. If there are, one group of the small group is cut off and one group of the medium group is input;

[0017] After the large group capacitor bank and the medium group capacitor bank are both input, the small group capacitor bank is directly switched according to the reactive power demand;

[0018] For the removal of cyclic switching:

[0019] When the over-compensation amount of the power supply system is greater than the large group capacitor bank, the large group capacitor bank is preferentially removed, then the medium group capacitor bank, and finally the small group capacitor bank;

[0020] The capacitor banks of each group are arranged arbitrarily, and do not have to be arranged closely according to the terminal numbers, and there is no gap in the middle. When re-inputting, it meets the two principles of cyclic switching and the delay time after removal, and the state is marked as the input state. After the removed capacitor bank passes through the discharge link and is marked as the uninput state, it can be input again.

[0021] Optionally, the electrical signals of the power supply system include voltage signals and current signals.

[0022] Optionally, the parameter values include reactive power values or power factor values.

[0023] Optionally, the status quantities include the switching status quantities of the compensation branches.

[0024] Optionally, the main controller and the slave controller control the cyclic switching of the capacitor banks of the compensation branches through expandable IO ports, including:

[0025] The main controller samples the electrical signals of the power supply system, calculates the parameter values of the power supply system based on the sampled electrical signals, determines the status quantities of the switching status switches of the compensation branches of the power supply system, and selects the cyclic switching method according to the switching control method;

[0026] According to the parameter values, status quantities and the preset cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups, determine the optimal switching scheme of the conventional switching method in the independent working mode.

[0027] Optionally, in the independent working mode, the main controller uses the conventional ports to control the cyclic switching of the compensation branches.

[0028] Optionally, the main controller generates a switching instruction according to the switching scheme in the master-slave working mode, sends the switching instruction to the slave controller through the serial communication port, and controls the expandable IO port of the slave controller according to the switching instruction to control the cyclic switching of the compensation branches.

[0029] On the other hand, the present invention also proposes a reactive power compensation method for a reactive power compensation system based on cyclic switching, including:

[0030] When the number of compensation branches of the power supply system is less than or equal to 16, set the working mode of the main controller to the independent working mode;

[0031] In the independent working mode, control the cyclic switching of the capacitor banks of the compensation branches through the main controller;

[0032] When the number of compensation branches of the power supply system is greater than 16, set the working mode of the main controller to the master-slave working mode;

[0033] In the master-slave working mode, control the main controller and the slave controller to control the capacitor banks of the compensation branches or cyclic switching through the expandable IO ports based on serial communication.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The present invention provides a reactive power compensation system based on a controller, comprising: a master controller and a slave controller; the master controller is used to set the working mode. When the number of compensation branches in the power supply system is less than or equal to 16, the working mode is set to the independent working mode. In the independent working mode, the master controller controls the cyclic switching of the capacitor banks of the compensation branches. When the number of compensation branches in the power supply system is greater than 16, the working mode is set to the master-slave working mode. In the master-slave working mode, the master controller and the slave controller control the cyclic switching of the capacitor banks of the compensation branches through the expandable IO ports of serial communication; the master controller is used to set the capacitor capacity parameters of the main body and the slave controller. The set parameters include three groups of common compensation capacities of small, medium and large, and each group of capacity corresponds to the port number of the local machine or the slave controller. Capacitors with equal capacity are used for cyclic switching. The present invention can complete the reactive power compensation with more than 16 compensation branches without using an IO port expansion module, which can be completed through the connection between controllers, avoiding the problems of requiring debugging interfaces and being difficult to be compatible when using an IO port expansion module. Moreover, using the controller for control improves the working efficiency, reduces the labor cost, and has relatively high benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a structural diagram of the system of the present invention;

[0037] Figure 2 is a flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Now, exemplary embodiments of the present invention will be introduced with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not limitations on the present invention. In the drawings, the same unit / element uses the same reference numeral.

[0039] Unless otherwise specified, the terms (including scientific and technical terms) used herein have the ordinary meaning understood by those skilled in the art. In addition, it can be understood that the terms defined in the commonly used dictionary should be understood to have a meaning consistent with the context of their related fields, and should not be understood as idealized or overly formal meanings.

[0040] Example 1:

[0041] The present invention proposes a reactive power compensation system 100 based on cyclic switching, as Figure 1 shown, comprising: a master controller 101 and a slave controller 102;

[0042] The main controller 101 is used to set the working mode. When the number of compensation branches in the power supply system is less than or equal to 16, the working mode is set to the independent working mode. In the independent working mode, the main controller 101 controls the cyclic switching of the capacitor banks of the compensation branches. When the number of compensation branches in the power supply system is greater than 16, the working mode is set to the master-slave working mode. In the master-slave working mode, the main controller 101 and the slave controller 102 control the cyclic switching of the capacitor banks of the compensation branches through the expandable IO ports of serial communication;

[0043] The main controller 101 is used to set the capacitor capacity parameters of the main body and the slave controller 102. The set parameters include three groups of common compensation capacities of small, medium and large. Each group of capacity corresponds to the port number of the local machine or the slave controller 102. Capacitors with equal capacity are used for cyclic switching.

[0044] Among them, the main controller 101 and the slave controller 102 are connected through a serial communication port;

[0045] The communication mode of the serial communication port includes: RS485 communication mode.

[0046] Among them, the main controller 101 controls the cyclic switching of the capacitor banks of the compensation branches, including:

[0047] The main controller 101 samples the electrical signals of the power supply system, calculates the parameter values of the power supply system according to the sampled electrical signals, determines the state quantity of the switching state switch of the compensation branches of the power supply system, and selects the cyclic switching mode according to the parameter values and the state quantity;

[0048] If the cyclic switching mode is selected, then according to the parameter values, the state quantity and the preset cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups, the optimal switching scheme of the conventional switching mode in the independent working mode is determined;

[0049] The preset cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups is specifically:

[0050] For the input of cyclic switching:

[0051] When the large group capacitor bank in the power supply system is sufficient to input the reactive power demand compensation capacity shortage, the large group capacitor bank is preferentially input;

[0052] After the reactive power demand of the power supply system changes and the large capacitor bank cannot be switched in, when the medium capacitor bank can be switched in, check whether there are any unswitched capacitors in the large capacitor bank. If not, directly switch in the medium capacitor bank. If there are, then check whether there are any medium capacitor banks that have been switched in. If not, directly switch in the medium capacitor bank. If there are, disconnect one group of the medium capacitor bank and switch in one path of the large capacitor bank. When the medium capacitor bank cannot be switched in and the small capacitor bank can be switched in, check whether there are any unswitched capacitors in the medium capacitor bank. If not, directly switch in the small capacitor bank. If there are, then check whether there is any small capacitor bank that has been switched in. If not, directly switch in the small capacitor bank. If there are, disconnect one group of the small capacitor bank and switch in one group of capacitors in the medium capacitor bank;

[0053] After the large capacitor bank and the medium capacitor bank are both switched in, the small capacitor bank is directly switched according to the reactive power demand;

[0054] Regarding the disconnection for cyclic switching:

[0055] When the over-compensation amount of the power supply system is greater than that of the large capacitor bank, the large capacitor bank is preferentially disconnected, then the medium capacitor bank, and finally the small capacitor bank;

[0056] The capacitor banks of each group are arranged arbitrarily. There is no need to arrange them closely according to the terminal numbers, and there is no gap in the middle. When switching in again, it meets the two conditions of the cyclic switching principle and the delay time after disconnection, and the status is marked as the switched-in state. After the disconnected capacitor bank goes through the discharge link and is marked as the unswitched state, it can be switched in again.

[0057] Among them, the electrical signals of the power supply system include voltage signals and current signals.

[0058] Among them, the parameter values include reactive power values or power factor values.

[0059] Among them, the status quantities include the switching status quantities of the compensation branches.

[0060] Among them, the main controller 101 and the slave controller 102 control the cyclic switching of the capacitor banks of the compensation branches through expandable IO ports, including:

[0061] The main controller 101 samples the electrical signals of the power supply system, calculates the parameter values of the power supply system based on the sampled electrical signals, determines the status quantities of the switching status switches of the compensation branches of the power supply system, and selects the cyclic switching method according to the switching control method;

[0062] According to the parameter values, status quantities and the preset cyclic switching strategy based on the intelligent automatic conversion control algorithm of large and small groups, determine the optimal switching scheme of the conventional switching method in the independent working mode.

[0063] Among them, in the independent working mode, the main controller 101 uses the conventional ports to control the cyclic switching of the compensation branches.

[0064] Among them, the main controller 101 generates switching instructions according to the switching scheme in the master-slave working mode, and sends the switching instructions to the slave controller 102 through the serial communication port. According to the switching instructions, it controls the expandable IO ports of the slave controller 102 to control the cyclic switching of the compensation branches.

[0065] For the system proposed by the present invention, the main controller 101 supports independent operation and master-slave operation modes. Usually, when the number of compensation branches is within 16, it is set to the independent working mode for normal switching. When the number of compensation branches is greater than 16, it is set to the master-slave working mode. At this time, two controllers are used to expand the IO ports, one as the host and the other as the slave. The two are connected through the serial communication port, such as: RS485 communication method. The host transmits the measurement data and switching status to the slave, and the slave displays the grid parameters and the switching status of each compensation branch of this controller.

[0066] The parameter settings of the main controller 101 during operation include: independent working or master-slave working mode (host mode or slave mode). When set to the independent working mode, the controller works independently. When setting the master-slave working mode, multiple controllers work in parallel and are connected through serial communication lines.

[0067] Capacity setting includes: supporting three types of common compensation capacities (small, medium, and large), and equal-capacity capacitors support cyclic switching; the capacity arrangement is arranged in ascending order of the terminal block numbers (small, medium, and large), and the same-capacity capacitors are adjacent to each other without gaps.

[0068] When the master-slave working mode is selected, the two controllers need to be configured according to the capacity selection and implemented according to the above arrangement principle.

[0069] Parameter settings include: the number of small groups of capacity, the number of medium groups of capacity, and the number of large groups of capacity.

[0070] In the system of the present invention, the main controller 101 is responsible for sampling the three-phase voltage and current signals of the power supply system, calculating parameters such as voltage, current, active power, reactive power, power factor, and grid frequency. Among them, reactive power or power factor can be used as a control physical quantity to participate in the switching control of the capacitor bank. In the master-slave working mode, the main controller transmits the above grid parameters and digital quantity status (switching status) to the slave through the serial communication port. The slave switches the connected capacitor bank according to the communication protocol (controls the digital quantity output), and the slave also real-time feedbacks its status through the serial communication port, including the switching status.

[0071] The main controller 101 is responsible for calculating the control physical quantity, switching the capacitor bank, cyclic switching of equal-capacity capacitors, and outputting the optimal matching scheme for the three compensation capacity combinations.

[0072] The controller 102 is only responsible for executing commands and switching and controlling the connected capacitor banks.

[0073] Among them, cyclic switching only occurs within groups of the same capacity. Grouping is based on the capacitor capacity, usually in a multiple relationship, such as: 30, 60, 120, etc. In fact, it is the difference in the number of parallel capacitors, and the number of groups generally does not exceed 3 groups, such as: it can be divided into three groups of "small, medium, and large". Cyclic switching can occur within the same group. Purpose: To prevent the situation where individual capacitors are continuously connected while other groups of capacitors are not used, so as to evenly distribute the connection time of the capacitors and prevent their service life from being shortened due to continuous connection. Cyclic switching occurs when the controller detects a change in the reactive power of the power grid and executes the switching control of the capacitor bank.

[0074] Designing cyclic switching has the following advantages:

[0075] Evenly distribute the connection time of each capacitor in the group of the same capacity, and prevent the service life of individual capacitors from being shortened due to continuous connection.

[0076] In the system where the contactor is used as the capacitor switching switch, after the capacitor is disconnected, it must go through a discharge process, which lasts about 3 - 5 minutes. Only when the voltage across both ends drops below the safe value (50V) can it be connected again. Otherwise, a serious impact current superposition will occur, resulting in damage to the capacitor, and in severe cases, even directly causing the capacitor to explode.

[0077] Capacitors of equal capacity are usually grouped into one group, and cyclic switching is supported within the group. For example: divided into three groups of "small, medium, and large". Each group in cyclic switching corresponds to a circular queue, which stores which group of capacitors is connected. The queue includes: queue size (≥ the maximum number of controller output ports, which is 32), head pointer Head, and tail pointer Tail, and the remaining quantity (Head - Tail). Head points to the last connected capacitor, Tail points to the first connected capacitor group, Tail chases Head, and the remaining quantity refers to the number of connected capacitor groups.

[0078] When Head > Tail, the connected quantity is Head – Tail; when Head < Tail, the connected quantity is (Head – Tail) + MAX_LEN;

[0079] When Head == Tail, it is the judgment condition for the circular queue to be empty;

[0080] (Head + 1) % MAX_LEN == Tail is the judgment condition for the circular queue to be full;

[0081] A total of 3 queues are used, corresponding to the three groups of "small, medium, and large", to record the connected channel numbers and quantities.

[0082] Specific implementation method:

[0083] In the controller parameter settings, the attributes of each group of capacitors include: capacitance (occupying 8 bits), large / medium / small grouping number (occupying 2 bits, 0 - 2), controller output port number (occupying 5 bits, 0 - 31), local / external (occupying 1 bit, 0 / 1), and the storage space occupies a total of one word (16 bits). Advantages: Equal-capacitance capacitors can be arranged without being adjacent to each other, providing sufficient flexibility, avoiding the impact on use caused by damage to the controller ports, and providing freedom and flexibility for the arrangement of capacitors in the cabinet. When determining the capacity of a group of capacitors to be put into a certain grouping, when the controller works in the independent mode, it directly outputs through the port; in the master-slave mode, it is necessary to obtain the information of whether the capacitor of this circuit is local or external. If it is a local port, it directly outputs. On the external slave, the port number is output to the slave through the serial port, and the slave executes the IO port output operation.

[0084] When the number of compensation branches designed in the reactive power compensation system exceeds the actual output port number of a single controller, two controllers adopting the invention technology of this patent can be considered. The two machines are connected by a communication line and work in the master-slave mode.

[0085] The switching strategy of the present invention is specifically as follows:

[0086] A strategy is formed by combining cyclic switching and the intelligent automatic conversion control algorithm of large and small groups;

[0087] The intelligent automatic conversion control algorithm of large and small groups aims to prevent the situation where the combined compensation capacity of the capacitor bank of the reactive power compensation device (the capacitors that have been put into operation and the capacitor groups that have not been put into operation) does not form the best match with the reactive power demand of the power grid due to the change of the reactive power load of the power grid. It will calculate the total reactive power demand of the system (detected by the controller + the compensated capacity of the capacitors that have been put into operation), and determine a reasonable output combination scheme according to the pre-generated switching combination table (Appendix Material 1: Reactive Power Compensation Cyclic Switching Output Combination Table). (How many large groups to put into operation, how many medium groups to put into operation, small groups).

[0088] When the large group is sufficient to be put into operation for the reactive power demand compensation capacity lacking in the power grid, the large group is put into operation first. The large group has the highest compensation priority, and by analogy: the medium group is the second, and the small group has the lowest priority.

[0089] When the reactive power demand of the system changes and the large group cannot be put into operation, but the medium group is sufficient to be put into operation: At this time, it is judged whether there are unput capacitors in the large grouping. If not, the medium group is directly put into operation; if there are, it is further judged whether there is an already put-in medium group. If not, the medium group is directly put into operation. If there is, one group of the medium grouping is cut off and one large grouping is put into operation. (The numbers change from 5 -> 6 and from 9 -> 10)

[0090] By analogy, when the medium group cannot be put into operation and the small group is sufficient to be put into operation: At this time, it is judged whether there are unput capacitors in the medium grouping. If not, the small group is directly put into operation; if there are, it is further judged whether there is an already put-in small group. If not, the small group is directly put into operation. If there is, one group of the small grouping is cut off and one group of the medium grouping is put into operation.

[0091] After the large groups and medium groups are all put into operation, the small groups are directly switched on and off according to the reactive power demand (the numbers change from 14 to 15, 16, 17, 18);

[0092] The cut-off operation is the same: if the over-compensation amount is greater than the capacity of the large group, the large group is preferentially cut off, and then the medium group and the small group. The priority order is: large group, medium group, small group;

[0093] When the capacitors in each switching group are put into operation again, they follow the principle of cyclic input, and the state is recorded as put into operation. The cut-off capacitors will not be put into operation immediately and must go through the discharge link. The capacitor state is marked as discharge delay until the delay time arrives and the voltage across the capacitor drops below the safe voltage value, and the state changes to the non-put-in state.

[0094] Example 2:

[0095] The present invention proposes a reactive power compensation method S200 for a reactive power compensation system based on cyclic switching, as Figure 2 shown, including:

[0096] S201. When the number of compensation branches in the power supply system is less than or equal to 16, set the working mode of the main controller to the independent working mode;

[0097] S202. In the independent working mode, through the main controller, control the cyclic switching of the capacitor banks of the compensation branches;

[0098] S203. When the number of compensation branches in the power supply system is greater than 16, set the working mode of the main controller to the master-slave working mode;

[0099] S204. In the master-slave working mode, control the main controller and the slave controller to control the capacitor banks of the compensation branches or cyclic switching through the expandable IO ports based on serial communication.

[0100] The present invention can complete the reactive power compensation with more than 16 compensation branches without using an IO port expansion module, which can be completed through the connection between controllers, avoiding the problems of requiring debugging interfaces and being difficult to be compatible when using an IO port expansion module. Moreover, using the controller for control improves the working efficiency, reduces the labor cost, and has relatively high benefits.

[0101] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript, etc.

[0102] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0103] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means realizes the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0104] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0105] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concepts. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A reactive power compensation system based on cyclic switching, characterized in that: include: Master controller and slave controller; The main controller is used to set the working mode. When the compensation branches of the power supply system are less than or equal to 16, the working mode is set to an independent working mode. In the independent working mode, the main controller controls the cyclic switching of the compensation branch capacitor group. When the compensation branches of the power supply system are greater than 16, the working mode is set to a master-slave working mode. In the master-slave working mode, the main controller and the slave controller control the cyclic switching of the compensation branch capacitor group through an expandable IO port of serial communication. The master controller is used to set the capacitor capacity parameters of the main body and the slave controller. The set parameters include three groups of small, medium and large common compensation capacities. Each group of capacity corresponds to the port number of the main body or the slave controller. Capacitors of equal capacity are used for cyclic switching. The main controller controls the cyclic switching of the compensation branch capacitor bank, including: The main controller samples the electrical signal of the power supply system, calculates the parameter value of the power supply system according to the sampled electrical signal, determines the state quantity of the compensation branch switching state switch of the power supply system, and selects the cyclic switching mode according to the parameter value and the state quantity; If the cyclic switching mode is selected, the optimal switching scheme of the conventional switching mode under the independent working mode is determined according to the parameter value, the state quantity and the preset cyclic switching strategy based on the large and small group intelligent automatic conversion control algorithm; The preset cyclic switching strategy based on the large-group intelligent automatic conversion control algorithm is specifically: For the input of cyclic switching: When the power supply system lacks reactive demand compensation capacity and the large group of capacitors is sufficient to be put into use, the large group of capacitors will be put into use first; After the reactive power demand of the power supply system changes, the large capacitor group cannot be put into operation, and the medium capacitor group can be put into operation, it is judged whether there are unused capacitors in the large group. If not, the medium capacitor group is directly put into operation. If yes, it is judged whether there are already put into operation medium capacitors. If not, the medium capacitor group is directly put into operation. If yes, one group of the medium group is cut off and one large group is put into operation. If the medium capacitor group cannot be put into operation and the small capacitor group can be put into operation, it is judged whether there are unused capacitors in the middle group. If not, the small capacitor group is directly put into operation. If yes, it is judged whether there are already put into operation small groups. If not, the small capacitor group is directly put into operation. If yes, one group of the small group is cut off and one group of capacitors is put into operation in the middle group. After the large capacitor group and the medium capacitor group are switched on, the small capacitor group is switched on directly according to the reactive power demand; Resection for cyclic cutting: When the overcompensation amount of the power supply system is greater than that of the large capacitor group, the large capacitor group is removed first, then the medium capacitor group, and finally the small capacitor group; The capacitor groups do not have to be arranged closely according to the terminal numbers, with no space in between. When they are put back into operation, they must meet the two requirements of the cyclic switching principle and the delay time after removal, and the status is marked as the put-in-operation state. After the capacitor group after removal goes through the discharge link, it is marked as the not-put-in-operation state and can be put into operation again.

2. The reactive power compensation system according to claim 1, characterized in that: The master controller and the slave controller are connected via a serial communication port; The communication mode of the serial communication port includes: RS485 communication mode.

3. The reactive power compensation system according to claim 1, characterized in that: The electrical signal of the power supply system includes: a voltage signal and a current signal.

4. The reactive power compensation system according to claim 1, characterized in that: The master controller and the slave controller control the cyclic switching of the compensation branch capacitor group through an expandable IO port, including: The main controller samples the electrical signal of the power supply system, calculates the parameter value of the power supply system according to the sampled electrical signal, determines the state quantity of the switching state switch of the compensation branch of the power supply system, and selects the cyclic switching mode according to the switching control mode; According to the parameter values, state quantities and a preset cyclic switching strategy based on a large-group intelligent automatic conversion control algorithm, an optimal switching scheme for the conventional switching method in the independent working mode is determined.

5. The reactive power compensation system according to claim 1, characterized in that: In the independent working mode, the main controller uses the conventional port to control the cyclic switching of the compensation branch.

6. The reactive power compensation system according to claim 1, characterized in that: The master controller generates a switching instruction according to the switching scheme in the master-slave working mode, sends the switching instruction to the slave controller through the serial communication port, and controls the expandable IO port of the slave controller according to the switching instruction to control the cyclic switching of the compensation branch.

7. The reactive power compensation system according to claim 1, characterized in that: The parameter value includes: reactive power value or power factor value; The state quantity includes: the switching state quantity of the compensation branch.

8. A reactive power compensation method using any one of the reactive power compensation systems based on cyclic switching according to claims 1 to 7, comprising: When the number of compensation branches of the power supply system is less than or equal to 16, the main controller working mode is set to independent working mode; In the independent working mode, the main controller is used to control the cyclic switching of the compensation branch capacitor group; When the number of compensation branches of the power supply system is greater than 16, the main controller is set to work in master-slave mode; In the master-slave working mode, the master controller and the slave controller are controlled through an expandable IO port based on serial communication to control the cyclic switching of the compensation branch capacitor group.

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