Reactive compensation voltage regulation device and system for small low-voltage power grid

Abstract

The invention provides a reactive compensation voltage regulation device and system for a small low-voltage power grid, and belongs to the technical field of reactive compensation of power systems. The device comprises a microprocessor, a voltage sampling module and a plurality of capacitor branches connected in parallel; one path of the fuse of each capacitor branch is connected to the live wire of the confluence busbar, the other path of the fuse is connected to the input end of the voltage sampling module, one path of the capacitor of each capacitor branch is connected to the zero wire of the confluence busbar, and the other path of the capacitor is connected to the input end of the voltage sampling module; the microprocessor determines a phase voltage and a load reactive power according to the obtained incoming current and compensation current of the reactive compensation voltage regulation device and the total afflux voltage of each capacitor branch; and controlling a relay of the capacitor branch to execute switching according to the phase voltage and the load reactive power. Based on the device, the invention also provides a reactive compensation voltage regulation system. According to the invention, the requirements of reactive compensation precision and response speed in a low-voltage small power grid environment are met.

Description

Technical Field

[0001] The invention belongs to the technical field of reactive power compensation of electric power systems, and in particular relates to a reactive power compensation voltage regulating device and system for small low-voltage power grids. Background Art

[0002] Reactive power compensation equipment plays an extremely important role in releasing power capacity, improving system voltage and reducing active power loss in the power system. A small power grid refers to a small power generation and distribution system composed of distributed power sources, energy storage devices, energy conversion devices, related loads and monitoring and protection devices. The power sources in a small power grid are mostly distributed power sources with small capacity and small short-circuit capacity. The voltage difference before and after the reactive power compensation equipment is put into use is: ,in, is the voltage before reactive power compensation. It can be seen that the steady-state voltage increase value after installing reactive power compensation equipment is Short-circuit capacity on the power supply side of the small grid Inversely proportional to the compensation capacity of the reactive power compensation equipment Proportional to short-circuit capacity The smaller the small power grid, the more serious the system voltage fluctuation caused by reactive power fluctuation, and the more significant the boosting effect of reactive power compensation equipment. Therefore, the main functions of reactive power compensation equipment in small power grids are to reduce the reactive power output on the power supply side and release the maximum capacity of the active power of the power supply; the second is to adjust the reactive power balance between the power supply and the load, and control and stabilize the system voltage. Therefore, reactive power compensation equipment plays an extremely important role in releasing power supply capacity, improving system voltage and reducing active power loss in the power system.

[0003] However, conventional reactive power compensation equipment in power systems is generally used in distribution networks with large short-circuit capacity, and its control target cannot solve the reactive voltage problem. Conventional reactive power compensation equipment in power systems is directly used in small power grids with small short-circuit capacity. There are the following problems that need to be solved: First, the compensation accuracy is low. The power capacity of small power grids is small, and the power of their electrical equipment is less than the power capacity, and the types are complicated. The change range of reactive power during operation is large. Small power grids require reactive power compensation equipment to compensate reactive power as delicately as possible, on the one hand, to minimize the reactive output on the power supply side, and on the other hand, to make the voltage level of the system the most stable; while the number of groups of conventional reactive power compensation equipment in power systems is small, and the group capacity is large. Improper configuration can easily cause over-compensation or under-compensation, which cannot meet the reactive power compensation accuracy requirements in small power grid environments. Second, the compensation speed is slow. Since the system voltage of small power grids is very sensitive to reactive power, reactive power compensation equipment is required to achieve real-time reactive power balance. The primary control target of conventional reactive power compensation equipment in power systems is not to solve the reactive voltage problem. In addition, in order to avoid switching oscillation, delay processing is also performed on the control algorithm, and the response time does not meet the response speed requirements in small power grid environments. How to meet the requirements of reactive power compensation accuracy and response speed in low-voltage small power grid environments, prevent over-compensation or under-compensation in low-voltage small power grid environments, achieve reactive power compensation accuracy requirements suitable for small power grid environments, and prevent low-voltage disconnection caused by excessive reactive voltage fluctuations in small power grids are technical issues that need to be solved. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a reactive power compensation voltage regulation device and system for a small low-voltage power grid, which can meet the reactive power compensation accuracy and response speed requirements in a low-voltage small power grid environment, and prevent over-compensation or under-compensation operating conditions from occurring in a low-voltage small power grid environment.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A reactive power compensation voltage regulating device for a small low-voltage power grid comprises: a microprocessor, a voltage sampling module and a plurality of capacitor branches connected in parallel; One way of the fuse of each capacitor branch is connected to the live line of the busbar, and the other way of the fuse is connected to the input end of the voltage sampling module; one way of the capacitor of each capacitor branch is connected to the neutral line of the busbar, and the other way of the capacitor is connected to the input end of the voltage sampling module; The microprocessor is used to obtain the incoming line current on the voltage bus connected to the reactive compensation voltage regulating device, the compensation current on the connected compensation bus, and obtain the total incoming voltage of each capacitor branch by connecting to the output end of the voltage sampling module, and determine the output phase voltage and load reactive power according to the incoming line current, compensation current and total incoming voltage; The output end of the microprocessor is connected to the relay of each capacitor branch, and controls the relay of the capacitor branch to perform switching according to the value of the phase voltage and the value of the load reactive power.

[0006] Furthermore, two insulating cross braces are fixed on the upper side of the inner shell of the reactive power compensation voltage regulating device for installing the busbar live wire and the busbar neutral wire.

[0007] Furthermore, the reactive power compensation voltage regulating device also includes an incoming line circuit breaker, a working power supply and a front panel; The inlet circuit breaker and the working power supply are installed and fixed on the top of the shell of the device body; multiple internal threaded columns are horizontally connected between the two side vertical plates of the shell of the device body to strengthen the structural strength of the shell of the device body; The front panel and the body shell are fastened together by screws, and grounding marks are provided at the mounting holes of the vertical plates on both sides of the body shell.

[0008] Furthermore, the capacitor branch specifically includes: a fuse, a relay, a diode, a capacitor and a discharge resistor; One end of the fuse is connected to the live wire of the busbar, and the other end is connected to one end of the normally open contact of the corresponding relay, the other end of the normally open contact is connected to one end of the corresponding capacitor, and the other end of the capacitor is connected to the neutral wire of the busbar; The two ends of the discharge resistor are respectively connected in parallel with the two ends of the capacitor; the bottom of the capacitor is provided with a fastening screw, which is laterally fastened inside the shell of the shell in sequence using nuts; The two ends of the diode are respectively connected in parallel with the two ends of the normally open contact of the relay.

[0009] Furthermore, the capacitor branch is a small-capacity capacitor branch whose capacity is smaller than a capacity threshold.

[0010] Furthermore, the microprocessor obtains the total incoming voltage of each capacitor branch by connecting to the output end of the voltage sampling module, and the process of determining the output phase voltage and load reactive power according to the incoming line current, the compensation current and the total incoming voltage includes: The voltage sampling module converts the incoming line current, compensation current and total incoming voltage from analog real-time signals into digital real-time signals and transmits them to the microprocessor to obtain the total incoming line current. , Phase voltage , Phase Angle and compensation current ; The calculation formula of load reactive power is: ;in, is the current transformer ratio; is the voltage transformer ratio; is the load reactive power.

[0011] Furthermore, according to the value of the phase voltage and the value of the load reactive power, the specific process of controlling the relay of the capacitor branch to perform switching includes: Set load reactive power Upper limit and upper limit , the upper limit of phase voltage and upper limit ; Utilize load reactive power Upper limit and upper limit , phase voltage Upper limit and upper limit Divide phase voltage and reactive power into preset areas; According to load reactive power The value and phase voltage The value of is used to determine the preset area, and the relay of the capacitor branch is controlled to perform switching according to the setting of the preset area.

[0012] Furthermore, the microprocessor first determines the phase voltage before controlling the capacitor branch relay to switch according to the setting of the preset area. The zero crossing point of the reactive power compensation voltage regulating device is determined, and then the time for issuing the input command is calculated according to the time when the relay contacts are closed or released, so as to control the electromagnetic coil of the relay to input or cut off the capacitor branch near the zero crossing point of the reactive power compensation voltage regulating device.

[0013] The present invention also proposes a reactive power compensation voltage regulation system for a small low-voltage power grid, comprising: a plurality of reactive power compensation voltage regulation devices, a first current transformer connected to a voltage bus, a main circuit breaker connected to a compensation bus, and a second current transformer; The A phase line, B phase line, C phase line and N neutral line of the compensation bus are respectively connected to the A phase line, B phase line, C phase line and N neutral line of the voltage bus in sequence through the main circuit breaker QF1; the first current transformer and the second current transformer are both connected to the microprocessor of each reactive power compensation voltage regulating device; and adjacent reactive power compensation voltage regulating devices are connected in communication; The compensation bus A phase line is connected with a plurality of reactive compensation voltage regulating devices; the compensation bus B phase line is connected with a plurality of reactive compensation voltage regulating devices; and the compensation bus C phase line is connected with a plurality of reactive compensation voltage regulating devices.

[0014] Furthermore, when the adjacent reactive compensation voltage regulating devices are communicated with each other, any reactive compensation voltage regulating device is set as the master device, and other reactive compensation voltage regulating devices except the master device are slave devices; the master device uniformly controls the slave devices through internal communication lines.

[0015] The effects provided in the content of the invention are only the effects of the embodiments, not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects: The present invention proposes a reactive power compensation voltage regulating device and system for a small low-voltage power grid, belonging to the technical field of reactive power compensation of power systems. The device comprises: a microprocessor, a voltage sampling module and a plurality of parallel capacitor branches; the fuse of each capacitor branch is connected to the busbar live line through one path, and the fuse is connected to the input end of the voltage sampling module through another path; the capacitor of each capacitor branch is connected to the busbar neutral line through one path, and the capacitor is connected to the input end of the voltage sampling module through another path; the microprocessor is used to obtain the incoming line current on the voltage busbar connected to the reactive power compensation voltage regulating device, the compensation current on the connected compensation busbar, and the total incoming voltage of each capacitor branch is obtained by connecting with the output end of the voltage sampling module, and the phase voltage and load reactive power are determined according to the incoming line current, the compensation current and the total incoming voltage; the output end of the microprocessor is connected to the relay of each capacitor branch, and the relay of the capacitor branch is controlled to perform switching according to the value of the phase voltage and the value of the load reactive power. Based on a reactive power compensation voltage regulating device for a small low-voltage power grid, a reactive power compensation voltage regulating system for a small low-voltage power grid is also proposed. The present invention improves the control accuracy of reactive power compensation, achieves a millisecond-level response speed, meets the requirements for reactive power compensation accuracy and response speed in a low-voltage small power grid environment, prevents over-compensation or under-compensation in a low-voltage small power grid environment, achieves reactive power compensation accuracy requirements suitable for a small power grid environment, and prevents low-voltage disconnection of a small power grid due to excessive reactive voltage fluctuations.

[0016] The present invention provides a reactive power compensation voltage regulating device for a small low-voltage power grid, which has the advantages of simple structure, low operation loss, flexible combination configuration, convenient maintenance and repair, and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a hardware connection diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Embodiment 1 of the present invention; Figure 2 This is an internal wiring diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Embodiment 1 of the present invention; Figure 3 It is a regional division diagram of the voltage-reactive power nine-region diagram control method proposed in Example 1 of the present invention; Figure 4 This is an appearance diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Embodiment 1 of the present invention; Figure 5This is a connection diagram of a reactive power compensation voltage regulation system for a small low-voltage power grid proposed in Example 2 of the present invention. DETAILED DESCRIPTION

[0018] In order to clearly illustrate the technical features of the present solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings. The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. In addition, the present invention may repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. It should be noted that the components illustrated in the accompanying drawings are not necessarily drawn to scale. The present invention omits the description of known components and processing techniques and processes to avoid unnecessary limitations on the present invention.

[0019] Example 1 Embodiment 1 of the present invention proposes a reactive power compensation voltage regulating device for a small low-voltage power grid, which is used to solve the technical problems existing in reactive power compensation of small low-voltage power grids in the prior art. Embodiment 1 of the present invention proposes a reactive power compensation voltage regulating device for a small low-voltage power grid, comprising: a microprocessor, a voltage sampling module and a plurality of capacitor branches connected in parallel; One way of the fuse of each capacitor branch is connected to the live line of the busbar, and the other way of the fuse is connected to the input end of the voltage sampling module; one way of the capacitor of each capacitor branch is connected to the neutral line of the busbar, and the other way of the capacitor is connected to the input end of the voltage sampling module; The microprocessor is used to obtain the incoming line current on the voltage bus connected to the reactive compensation voltage regulating device, the compensation current on the connected compensation bus, and obtain the total incoming voltage of each capacitor branch by connecting to the output end of the voltage sampling module, and determine the output phase voltage and load reactive power according to the incoming line current, compensation current and total incoming voltage; The output end of the microprocessor is connected to the relay of each capacitor branch, and controls the relay of the capacitor branch to perform switching according to the value of the phase voltage and the value of the load reactive power.

[0020] Figure 1 This is a hardware connection diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Embodiment 1 of the present invention; The reactive power compensation voltage regulating device includes an incoming line circuit breaker, a working power supply and a front panel; the incoming line circuit breaker and the working power supply are installed and fixed on the top of the device body shell; 6 internal threaded columns are horizontally connected between the two side vertical plates of the device body shell to strengthen the structural strength of the device body shell; screws are used to fasten the front panel and the device body shell, and grounding marks are provided at the mounting holes of the vertical plates on both sides of the device body shell, which can safely ground the device body shell of the reactive power compensation voltage regulating device.

[0021] The reactive power compensation voltage regulating device also includes a power device circuit board, on which are welded corresponding fuses, small large-capacity relays, freewheeling diodes and discharge resistors for each capacitor switching operation. The power device circuit board is installed at the top of each capacitor and fixed to the top by capacitor leads. The internal main circuit of the reactive power compensation voltage regulating device proposed in the present application is composed of at least 10 groups of capacitor branches with a capacity not greater than 1kvar connected in parallel.

[0022] Figure 2 This is an internal wiring diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention; each capacitor branch is composed of a fuse (U1~Un), a relay (K1~Kn), a freewheeling diode (D1~Dn), a capacitor (C1~Cn) and a discharge resistor (R1~Rn). The capacitor branch in this application is a small-capacity capacitor branch, the relay adopts a small-capacity relay, and the capacitor adopts a small-capacity capacitor.

[0023] The connection method of the capacitor branch is: one end of the fuse is connected to the live wire of the busbar, the other end is connected to one end of the normally open contact of the corresponding relay, the other end of the normally open contact is connected to one end of the corresponding capacitor, and the other end of the capacitor is connected to the neutral wire of the busbar; The two ends of the discharge resistor are respectively connected in parallel with the two ends of the capacitor; the bottom of the capacitor is provided with a fastening screw, which is laterally fastened inside the shell of the shell in sequence using nuts; the two ends of the diode are respectively connected in parallel with the two ends of the normally open contacts of the relay.

[0024] The bottom of the capacitor is provided with a fastening screw, and at least 10 capacitors with the fastening screws at the bottom are transversely fastened in sequence to the mounting holes on the inner sides of the two side vertical plates of the body shell using nuts.

[0025] Two insulating cross braces are fixed on the upper side of the inner shell of the reactive power compensation voltage regulating device, which are used to install the busbar live wire and the busbar neutral wire, and the incoming line end is connected to the output of the incoming line circuit breaker.

[0026] The wiring terminals of each capacitor branch fuse are connected to the live wire of the busbar in turn, and the other end is connected to one end of the normally open contact of the corresponding relay. When a short circuit occurs inside the capacitor, the fuse will cut off the capacitor branch to provide short-circuit protection. The other end of the normally open contact of each capacitor branch relay is connected to one end of the corresponding capacitor, and the other end is connected to the neutral wire of the busbar in turn. The two ends of the discharge resistor of each capacitor branch are respectively connected in parallel with the two ends of the capacitor. When the capacitor branch is not powered, it is always in a discharged state, so that the capacitor cannot store charge inside. The two ends of the freewheeling diode of each capacitor branch are connected in parallel with the two ends of the normally open contact of the relay. The freewheeling diode always keeps the capacitor in a forward charging state. The capacitor is put into operation near the zero point of the positive half cycle to reduce the inrush current and operating overvoltage.

[0027] Combination Figure 1 , Figure 2 and Figure 4 Let me explain in detail. Figure 4 This is an appearance diagram of a reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention; the reactive power compensation voltage regulating device also includes a microcomputer measurement and control circuit board. The microcomputer measurement and control circuit board is fixed to the welding nut column set on the back of the front panel with screws, a display window is set in the middle and upper part of the front panel, the LED display part of the microcomputer measurement and control circuit board is installed directly below the display window of the front panel, and the internal wiring terminal I / O interface set on the microcomputer measurement and control circuit board is connected to the coil terminal of each relay using a plug-in connector; a 12P through-the-wall wiring terminal is installed on the upper and lower sides of the front panel, 2 system current terminals, 2 compensation current terminals and 4 AC voltage sampling signals, 4 spare terminals, connected to the microcomputer measurement and control circuit board by the upper 12P through-the-wall wiring terminal; 2 internal communication terminals, 2 external communication terminals, 2 fault alarm terminals, 2 protection locking terminals and 4 spare terminals are connected to the microcomputer measurement and control circuit board by the lower 12P through-the-wall wiring terminal; when the reactive power compensation voltage regulating device is in operation, its working status and operating parameters can be viewed through the display window on the panel.

[0028] The microcomputer measurement and control circuit board has an internal communication circuit, an external communication circuit, and a microprocessor. The microcomputer measurement and control circuit board can convert the analog real-time signals of the incoming current terminal, voltage terminal input and compensation current terminal connected to the reactive compensation voltage regulating device into digital real-time signals and transmit them to the microprocessor on the microcomputer measurement and control circuit board.

[0029] The voltage sampling module converts the incoming line current, compensation current and total incoming voltage from analog real-time signals into digital real-time signals and transmits them to the microprocessor to obtain the total incoming line current. , Phase voltage , Phase Angle and compensation current ; The calculation formula of load reactive power is: ;in, is the current transformer ratio; is the voltage transformer ratio; is the load reactive power.

[0030] The strategy of switching capacitor branch is based on the principle of "balance reactive power locally to ensure voltage compliance". According to the new reactive voltage nine-domain diagram control method, the specific process of controlling the capacitor branch relay to perform switching according to the phase voltage value and the load reactive power value includes: setting the load reactive power Upper limit and upper limit , the upper limit of phase voltage and upper limit ; Utilize load reactive power Upper limit and upper limit , phase voltage Upper limit and upper limit Divide phase voltage and reactive power into preset areas; according to load reactive power The value and phase voltage The value of load reactive power The value and phase voltage The preset area where the capacitor is located controls the relay of the capacitor branch to perform switching according to the setting of the preset area.

[0031] Figure 3 This is a regional division diagram of the voltage reactive power nine-region diagram control method proposed in Example 1 of the present invention; the microprocessor on the microcomputer measurement and control circuit board is based on the reactive power of the load and phase voltage In the area where the load is located, the meter is checked or the instructions of the voltage and reactive power control system of the upper level are followed to control the switching action of the small-capacity capacitor branch to reduce the reactive power of the load. and phase voltage Running in area 0 (the shaded area in the figure), the control rules of each area are as follows: Area 0: voltage is qualified, reactive power is balanced; no action; Area 1: The voltage exceeds the upper limit and the reactive power is balanced; the previous level is downgraded first. If the distribution transformer is already at the lowest level, the small-capacity capacitor branches are removed one by one until the voltage is qualified; Area 2: The higher the voltage is, the lower the reactive power is. The previous level will be downgraded first. If the distribution transformer is already at the lowest level, the small-capacity capacitor branches will be removed one by one until the voltage is qualified. Area 3: The voltage is qualified, but the reactive power exceeds the lower limit; small-capacity capacitor branches are added one by one until the reactive power is qualified; Area 4: The lower the voltage limit, the lower the reactive power limit; small-capacity capacitors are added one by one until both the voltage and reactive power are qualified. If there is no capacitor to be added, the gear is upgraded to the next level; Area 5: The voltage is lower than the lower limit, and the reactive power is balanced; the previous level is upgraded first. If the distribution transformer is already at the highest level, small-capacity capacitor branches are added one by one until the reactive power is qualified; Area 6: The lower the voltage limit, the higher the reactive power limit; the previous level is upgraded first. If the distribution transformer is already at the highest level, small-capacity capacitor branches are added one by one until both the voltage and reactive power are qualified; Area 7: The voltage is qualified, but the reactive power exceeds the upper limit; small-capacity capacitor branches are removed one by one until the reactive power is qualified; Area 8: The higher the voltage limit, the higher the reactive power limit; cut off small-capacity capacitor branches one by one until both the voltage and reactive power are qualified. If there is no capacitor to cut, downgrade to the previous level.

[0032] The microprocessor on the microcomputer control circuit board detects the phase voltage before issuing a start-up instruction to the capacitor branch. The relay is controlled to detect the zero-crossing point of the voltage in the reactive compensation voltage regulating device, and then calculate the time to send out the input command according to the time when the relay contacts are closed or released, so as to control the electromagnetic coil of the relay to input or cut off the capacitor branch near the zero-crossing point of the voltage in the reactive compensation voltage regulating device, so as to reduce the input inrush current and operating overvoltage of the relay; and the control functions of first-in, first-out and cyclic input and output can be realized; A reactive compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention improves the control accuracy of reactive compensation, achieves a millisecond-level response speed, meets the reactive compensation accuracy and response speed requirements in a low-voltage small power grid environment, prevents over-compensation or under-compensation in a low-voltage small power grid environment, achieves reactive compensation accuracy requirements suitable for a small power grid environment, and prevents low-voltage disconnection of a small power grid due to excessive reactive voltage fluctuations.

[0033] The reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention has a simple structure, low operating loss, flexible combination configuration, convenient maintenance and repair, and low manufacturing cost.

[0034] The components used in the reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention are all common components in the domestic market. No special components that are imported or difficult to purchase are used. The market prices of all components are basically stable. Compared with power electronic reactive power compensation equipment, the production cost is lower and it has a good cost-effectiveness advantage.

[0035] Example 2 Based on the reactive power compensation voltage regulating device for a small low-voltage power grid proposed in Example 1 of the present invention, Example 2 of the present invention further proposes a reactive power compensation voltage regulating system for a small low-voltage power grid. The system comprises: a plurality of reactive power compensation voltage regulating devices proposed in Example 1 of the present invention, a first current transformer connected to the voltage bus, a main circuit breaker connected to the compensation bus, and a second current transformer; The A-phase line, B-phase line, C-phase line and N-neutral line of the compensation bus are respectively connected to the A-phase line, B-phase line, C-phase line and N-neutral line of the voltage bus in sequence through the main circuit breaker QF1; the first current transformer and the second current transformer are both connected to the microprocessor of each reactive power compensation voltage regulating device; and adjacent reactive power compensation voltage regulating devices are connected in communication; A plurality of reactive compensation voltage regulating devices are connected to the A phase line of the compensation bus; a plurality of reactive compensation voltage regulating devices are connected to the B phase line of the compensation bus; a plurality of reactive compensation voltage regulating devices are connected to the C phase line of the compensation bus.

[0036] The reactive power compensation voltage regulating device comprises: a microprocessor, a voltage sampling module and a plurality of capacitor branches connected in parallel; One way of the fuse of each capacitor branch is connected to the live line of the busbar, and the other way of the fuse is connected to the input end of the voltage sampling module; one way of the capacitor of each capacitor branch is connected to the neutral line of the busbar, and the other way of the capacitor is connected to the input end of the voltage sampling module; The microprocessor is used to obtain the incoming line current on the voltage bus connected to the reactive compensation voltage regulating device, the compensation current on the connected compensation bus, and obtain the total incoming voltage of each capacitor branch by connecting to the output end of the voltage sampling module, and determine the phase voltage and load reactive power according to the incoming line current, compensation current and total incoming voltage; The output end of the microprocessor is connected to the relay of each capacitor branch, and controls the relay of the capacitor branch to perform switching according to the value of the phase voltage and the value of the load reactive power.

[0037] Two insulating cross braces are fixed on the upper side of the inner shell of the reactive power compensation voltage regulating device for installing the busbar live wire and the busbar neutral wire.

[0038] The reactive power compensation voltage regulating device also includes an incoming line circuit breaker, a working power supply and a front panel; the incoming line circuit breaker and the working power supply are installed and fixed on the top of the device body shell; a plurality of internal threaded columns are horizontally connected between the two side vertical plates of the device body shell to strengthen the structural strength of the device body shell; the front panel and the device body shell are fastened with screws, and grounding marks are provided at the mounting holes of the vertical plates on both sides of the device body shell.

[0039] The capacitor branch specifically includes: a fuse, a relay, a diode, a capacitor and a discharge resistor; one end of the fuse is connected to the live wire of the busbar, and the other end is connected to one end of the normally open contact of the corresponding relay, the other end of the normally open contact is connected to one end of the corresponding capacitor, and the other end of the capacitor is connected to the neutral wire of the busbar; the two ends of the discharge resistor are respectively connected in parallel with the two ends of the capacitor; the bottom of the capacitor is provided with a fastening screw, which is laterally fastened inside the shell of the shell in sequence using nuts; the two ends of the diode are respectively connected in parallel with the two ends of the normally open contact of the relay.

[0040] The capacitor branch is a small-capacity capacitor branch whose capacity is smaller than the capacity threshold.

[0041] The microprocessor is connected to the output end of the voltage sampling module to obtain the total input voltage of each capacitor branch. The process of determining the output phase voltage and load reactive power according to the incoming line current, compensation current and total input voltage includes: The voltage sampling module converts the incoming line current, compensation current and total incoming voltage from analog real-time signals into digital real-time signals and transmits them to the microprocessor to obtain the total incoming line current. , Phase voltage , Phase Angle and compensation current ; The calculation formula for load reactive power is: ;in, is the current transformer ratio; is the voltage transformer ratio; is the load reactive power.

[0042] According to the value of the phase voltage and the value of the load reactive power, the specific process of controlling the capacitor branch relay to perform switching includes: setting the load reactive power Upper limit and upper limit , the upper limit of phase voltage and upper limit ; Utilize load reactive power Upper limit and upper limit , phase voltage Upper limit and upper limit Divide phase voltage and reactive power into preset areas; according to load reactive power The value and phase voltage The value of is used to determine the preset area, and the relay of the capacitor branch is controlled to perform switching according to the setting of the preset area.

[0043] The microprocessor first determines the phase voltage before controlling the capacitor branch relay to switch according to the preset area settings. The zero crossing point of the reactive power compensation voltage regulating device is determined, and then the time for issuing the input command is calculated according to the time when the relay contacts are closed or released, so as to control the electromagnetic coil of the relay to input or cut off the capacitor branch near the zero crossing point of the reactive power compensation voltage regulating device.

[0044] For the corresponding structure of a reactive compensation voltage regulation device for a small low-voltage power grid included in a reactive compensation voltage regulation system for a small low-voltage power grid proposed in Example 2 of the present application, reference can be made to the detailed description in Example 1 of the present invention.

[0045] Figure 5 A connection diagram of a reactive compensation voltage regulation system for a small low-voltage power grid proposed in Example 2 of the present invention; an incoming current detection transformer (TA1-TA3) connected to the voltage bus, a main circuit breaker (QF1) connected to the compensation bus, and a compensation current detection transformer (TA4-TA6) connected to the compensation bus, the voltage bus and the compensation bus respectively have an A phase line, a B phase line, a C phase line, and an N neutral line, and also include 1 to n reactive compensation voltage regulation devices connected to the compensation bus A phase line, 1 to n reactive compensation voltage regulation devices connected to the compensation bus B phase line, and 1 to n reactive compensation voltage regulation devices connected to the compensation bus C phase line.

[0046] The A-phase line, B-phase line, C-phase line and N-neutral line of the compensation bus are connected to the A-phase line, B-phase line, C-phase line and N-neutral line of the voltage bus in sequence through the main circuit breaker QF1 respectively. 3×1~n reactive compensation voltage regulating devices are connected between the A-phase line, B-phase line, C-phase line and N-neutral line of the compensation bus respectively, forming a star connection mode of phase compensation; each reactive compensation voltage regulating device is internally subdivided into at least 10 groups of small-capacity capacitor branches with a grouping capacity of no more than 1kvar to form a primary circuit. The smaller the grouping capacity and the more the number of groups, the higher the reactive compensation accuracy.

[0047] According to the reactive compensation capacity required by the reactive compensation voltage regulating device, a corresponding number of the reactive compensation voltage regulating devices of the present invention are connected in parallel to expand the capacity, any one of the reactive compensation voltage regulating devices of the present invention is connected to the incoming current and compensation current of the reactive compensation voltage regulating system and is set as the master device, and all other reactive compensation voltage regulating devices of the present invention are set as slave devices. The intelligent and precise reactive compensation voltage regulating unit of the present invention as the master device can rely on its internal communication line to connect all other intelligent and precise reactive compensation voltage regulating units of the present invention together, transmit operating data and control instructions, and perform unified regulation.

[0048] The working power input voltage of 85V-250V can operate normally. The working power is connected to the microcomputer measurement and control circuit board using a screw connector.

[0049] Embodiment 2 of the present invention proposes a reactive compensation voltage regulation system for a small low-voltage power grid, in which the connected reactive compensation voltage regulation devices are fully compatible with each other, redundancy can be reserved for hot standby during design, and spare devices can also be purchased to directly replace faulty devices. Each reactive compensation voltage regulation system of the present invention has a fault alarm indication, which greatly facilitates the maintenance of the reactive compensation voltage regulation system.

[0050] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment that includes a series of elements are inherent to the elements. In the absence of more restrictions, the elements limited by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment that includes the elements. In addition, the above-mentioned technical solution provided in the embodiment of the present application is consistent with the corresponding technical solution in the prior art in principle, and the part is not described in detail, so as not to repeat too much.

[0051] Although the above describes the specific implementation of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. For those skilled in the art, other different forms of modifications or deformations can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. On the basis of the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A reactive power compensation voltage regulating device for a small low-voltage power grid, characterized in that: include: A microprocessor, a voltage sampling module and a plurality of capacitor branches connected in parallel; One way of the fuse of each capacitor branch is connected to the live line of the busbar, and the other way of the fuse is connected to the input end of the voltage sampling module; one way of the capacitor of each capacitor branch is connected to the neutral line of the busbar, and the other way of the capacitor is connected to the input end of the voltage sampling module; The microprocessor is used to obtain the incoming line current on the voltage bus connected to the reactive compensation voltage regulating device, the compensation current on the connected compensation bus, and obtain the total incoming voltage of each capacitor branch by connecting to the output end of the voltage sampling module, and determine the phase voltage and load reactive power according to the incoming line current, compensation current and total incoming voltage; The output end of the microprocessor is connected to the relay of each capacitor branch, and controls the relay of the capacitor branch to perform switching according to the value of the phase voltage and the value of the load reactive power.

2. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 1, characterized in that: Two insulating cross braces are fixed on the upper side of the inner part of the shell of the reactive power compensation voltage regulating device, and are used to install the busbar live wire and the busbar neutral wire.

3. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 2, characterized in that: The reactive power compensation voltage regulating device also includes an incoming line circuit breaker, a working power supply and a front panel; The inlet circuit breaker and the working power supply are installed and fixed on the top of the shell of the device body; multiple internal threaded columns are horizontally connected between the two side vertical plates of the shell of the device body to strengthen the structural strength of the shell of the device body; The front panel and the body shell are fastened together by screws, and grounding marks are provided at the mounting holes of the vertical plates on both sides of the body shell.

4. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 1, characterized in that: The capacitor branch specifically includes: a fuse, a relay, a diode, a capacitor and a discharge resistor; One end of the fuse is connected to the live wire of the busbar, and the other end is connected to one end of the normally open contact of the corresponding relay, the other end of the normally open contact is connected to one end of the corresponding capacitor, and the other end of the capacitor is connected to the neutral wire of the busbar; The two ends of the discharge resistor are respectively connected in parallel with the two ends of the capacitor; the bottom of the capacitor is provided with a fastening screw, which is laterally fastened inside the shell of the shell in sequence using nuts; The two ends of the diode are respectively connected in parallel with the two ends of the normally open contact of the relay.

5. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 1, characterized in that: The capacitor branch is a small-capacity capacitor branch whose capacity is smaller than a capacity threshold.

6. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 1, characterized in that: The microprocessor is connected to the output end of the voltage sampling module to obtain the total input voltage of each capacitor branch. The process of determining the output phase voltage and load reactive power according to the incoming line current, compensation current and total input voltage includes: The voltage sampling module converts the incoming line current, compensation current and total incoming voltage from analog real-time signals into digital real-time signals and transmits them to the microprocessor to obtain the total incoming line current. , Phase voltage , Phase Angle and compensation current ; The calculation formula of load reactive power is: ;in, is the current transformer ratio; is the voltage transformer ratio; is the load reactive power.

7. A reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 6, characterized in that: According to the value of the phase voltage and the value of the load reactive power, the specific process of controlling the relay of the capacitor branch to perform switching includes: Set load reactive power Upper limit and upper limit , the upper limit of phase voltage and upper limit ; Utilize load reactive power Upper limit and upper limit , phase voltage Upper limit and upper limit Divide phase voltage and reactive power into preset areas; According to load reactive power The value and phase voltage The value of is used to determine the preset area, and the relay of the capacitor branch is controlled to perform switching according to the setting of the preset area.

8. The reactive power compensation voltage regulating device for a small low-voltage power grid according to claim 7, characterized in that: The microprocessor first determines the phase voltage before controlling the capacitor branch relay to switch according to the preset area settings. The zero crossing point of the reactive power compensation voltage regulating device is determined, and then the time for issuing the input command is calculated according to the time when the relay contacts are closed or released, so as to control the electromagnetic coil of the relay to input or cut off the capacitor branch near the zero crossing point of the reactive power compensation voltage regulating device.

9. A reactive power compensation voltage regulation system for a small low-voltage power grid, characterized in that: include: A plurality of reactive power compensation voltage regulating devices, a first current transformer connected to the voltage bus, a main circuit breaker connected to the compensation bus, and a second current transformer; The A phase line, B phase line, C phase line and N neutral line of the compensation bus are respectively connected to the A phase line, B phase line, C phase line and N neutral line of the voltage bus in sequence through the main circuit breaker QF1; the first current transformer and the second current transformer are both connected to the microprocessor of each reactive power compensation voltage regulating device; and adjacent reactive power compensation voltage regulating devices are connected in communication; A plurality of reactive power compensation voltage regulating devices are connected to the compensation bus phase A; A plurality of reactive compensation voltage regulating devices are connected to the compensation bus B phase line; a plurality of reactive compensation voltage regulating devices are connected to the compensation bus C phase line.

10. A reactive power compensation voltage regulation system for a small low-voltage power grid according to claim 9, characterized in that: When the adjacent reactive compensation voltage regulating devices are communicated with each other, any reactive compensation voltage regulating device is set as the master device, and other reactive compensation voltage regulating devices except the master device are slave devices; the master device uniformly controls the slave devices through internal communication lines.

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