CN106849125B - Intelligent capacitance compensation device and capacitance switching method - Google Patents
Intelligent capacitance compensation device and capacitance switching method Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for AC mains or AC distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses an intelligent capacitance compensation device, which comprises an intelligent measurement and control unit, a capacitance switching switch, a controller and a compensation capacitor; the intelligent measurement and control unit is in communication connection with the controller, the output end of the controller is connected with the capacitor switching switch, the intelligent measurement and control unit, the capacitor switching switch and the compensation capacitor are installed and fixed in the insulation box, the capacitor switching switch comprises a detection circuit and a magnetic latching relay, the detection circuit comprises a voltage transformer, a current transformer and an anti-impact capacitor, and the input end of the voltage transformer, the input end of the current transformer and the anti-impact capacitor are mutually connected in series. According to the invention, the intelligent measurement and control unit is used for collecting the electric parameters of the power grid system and calculating the power factor, zero-crossing switching of the compensation capacitor is realized through the capacitor switching switch according to the actual value of the power factor, the inrush current and arcing phenomena of the traditional compensation device in the switching process are avoided, and the service life of the device is prolonged.
Description
Technical Field
The invention relates to the field of power circuits, in particular to an intelligent capacitance compensation device and a capacitance switching method.
Background
The power factor is a parameter used for measuring the efficiency of an electrical system in the electrical field, and the low power factor proves that the energy used for establishing an electric field and a magnetic field in the system is high, namely the reactive power in the system is high.
Conventionally equipped devices such as motors and transformers in a power grid system belong to inductive loads, and the power grid system therefore needs to supply reactive power to these inductive loads during operation.
The technical means of compensating the reactive power of the power grid system and improving the power factor of the system in the field mainly comprises the capacitor in parallel in principle, and in actual operation, the reactive power controller is used for controlling the switching quantity of the capacitance compensation device so as to realize reactive power compensation operation. However, the switching process of the existing capacitance compensation device is operated only by means of mechanical components, so that the existing capacitance compensation device and a compensation system formed by peripheral components of the existing capacitance compensation device have the defects of complex wiring, large occupied space and the like, meanwhile, the capacitance compensation device is more serious in that the phenomena of inrush current and electric arcs easily occur in the switching process, larger damage is brought to the device, the device is easy to fail, and the service life of the device is reduced.
Disclosure of Invention
In view of the above problems, the present invention provides an intelligent capacitance compensation device and a capacitance switching method thereof.
The invention solves the technical problems as follows:
An intelligent capacitance compensation device, comprising:
And an intelligent measurement and control unit: the power factor calculating device is used for detecting the electric parameters of the power grid system and calculating the power factor of the power grid system;
a capacitive switching switch: the switching operation is used for executing the compensation capacitor;
a controller and a compensation capacitor;
The intelligent measurement and control unit is in communication connection with the controller, the output end of the controller is connected with the capacitor switching switch, the intelligent measurement and control unit, the capacitor switching switch and the compensation capacitor are installed and fixed in the insulation box, the capacitor switching switch comprises a detection circuit and a magnetic latching relay for controlling the switching of the compensation capacitor, the detection circuit is connected between a live wire and a zero line in series, the detection circuit comprises a voltage transformer, a current transformer and an anti-impact capacitor, the input end of the voltage transformer, the input end of the current transformer and the anti-impact capacitor are connected in series, the output end of the voltage transformer and the output end of the current transformer are connected with the input end of the controller respectively, and the input end of the magnetic latching relay is connected with the output end of the controller.
As a further improvement of the technical scheme, the intelligent measurement and control unit comprises an acquisition chip, and the model of the acquisition chip is CS5460A.
As a further improvement of the technical scheme, the magnetic latching relay further comprises a protection unit, wherein the protection unit comprises a temperature detection module and a phase failure detection module, the output end of the temperature detection module is connected with the input end of the controller, and the phase failure detection module is connected with the input end of the magnetic latching relay.
As a further improvement of the above technical solution, the temperature detection module includes a model STLM75 temperature sensor.
As a further improvement of the technical scheme, the open-phase detection module comprises a single-phase power supply sampling circuit, a reference power supply, a comparison circuit, a discharge circuit and a trigger circuit, wherein the input end of the single-phase power supply sampling circuit is connected with a single-phase power supply interface, the output end of the single-phase power supply sampling circuit is connected with the input end of the comparison circuit, the signal input interface is connected with the input end of the reference power supply, the output end of the reference power supply is respectively connected with the single-phase power supply sampling circuit and the comparison circuit, the output end of the comparison circuit is respectively connected with the input end of the trigger circuit and the input end of the discharge circuit, and the capacitor switching switch is respectively connected with the discharge circuit and the trigger circuit.
The beneficial effects of the invention are as follows: the intelligent measurement and control unit is used for collecting the electric parameters of the power grid system and calculating the power factor, zero-crossing switching of the compensation capacitor is realized through the capacitor switching switch according to the actual value of the power factor, the phenomenon of inrush current and arcing in the switching process of the traditional compensation device is avoided, the service life of the device is prolonged, in addition, the intelligent measurement and control unit is high in integration level and convenient to install wiring, and meanwhile, the intelligent measurement and control unit, the capacitor switching switch and the compensation capacitor are all installed in one insulation box, so that occupied space is reduced.
A capacitance switching method of an intelligent capacitance compensation device comprises the following steps:
step A: setting an input threshold and a cut-off threshold of a compensation capacitor, wherein the input threshold is smaller than the cut-off threshold, setting reactive power limit values of a power grid system under different apparent powers, and setting a detection period;
and (B) step (B): starting timing, wherein the timing time corresponds to the detection period;
step C: collecting electric parameters in a power grid system, and calculating the power factor, apparent power and reactive power of the power grid system, wherein the power factor and the reactive power are calculated by a collecting chip CS 5460A;
step D: judging whether the power factor of the power grid system is larger than 0 and smaller than an input threshold, if so, inputting a group of compensation capacitors, judging whether the power factor of the power grid system is larger than an ablation threshold or smaller than 0, and if so, cutting off one compensation capacitor; if the power factor of the power grid system is larger than the input threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, inputting a group of compensation capacitors, if the power factor of the power grid system is smaller than the cutoff threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, cutting off a group of compensation capacitors;
Step E: and (5) waiting for the end of the timing, and returning to the step B.
As a further improvement of the above technical solution, in the step a, a maximum temperature limit value of the compensation capacitor allowed to operate, an overvoltage protection threshold and an under-current blocking threshold are also required to be set.
As a further improvement of the above technical solution, the method further includes a step F, wherein the operation condition of the capacitance compensation device is self-detected, and the step F can be set at any position after the step a.
As a further improvement of the above technical solution, the step F includes:
f01: collecting the current temperature of the compensation capacitor, and cutting off the compensation capacitor if the current temperature of the compensation capacitor is greater than a temperature limit value;
f02: judging whether the power grid system is powered off, if so, cutting off all compensation capacitors;
f03: judging whether the voltage at two ends of the compensation capacitor is larger than an overvoltage protection threshold, and if so, cutting off the compensation capacitor;
F04: and judging whether the input current of the power grid system is smaller than an under-current blocking threshold, and if so, stopping the switching operation of the compensation capacitor.
As a further improvement of the above technical solution, the step D further includes collecting a voltage and current instantaneous value of the input end of the power grid system; if the compensation capacitor is put into operation, adding a first pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input voltage; if the compensation capacitor cutting operation is needed, adding a second pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input current; the first pulse electric signal and the second pulse electric signal have the same amplitude and opposite polarities, and the pulse width of the first pulse electric signal and the second pulse electric signal is larger than 1/4 period of the input voltage and the input current.
The compensation capacitor switching method has the beneficial effects that: according to the method, switching operation of the compensation capacitor is controlled according to the power factor and reactive power of the power grid system, switching is conducted only aiming at the power factor or reactive power in the prior art, the power grid system is enabled to run more stably, and lighting loss is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that are required to be used in the description of the embodiments will be briefly described below. It is evident that the drawings described are only some embodiments of the invention, but not all embodiments, and that other designs and drawings can be obtained from these drawings by a person skilled in the art without inventive effort.
FIG. 1 is a schematic block diagram of a capacitance compensation device of the present invention;
FIG. 2 is a schematic diagram of a detection circuit of the present invention;
FIG. 3 is a schematic view of the appearance and structure of the insulation box of the present invention;
FIG. 4 is a schematic block diagram of a phase failure detection module of the present invention;
FIG. 5 is a circuit diagram of a phase failure detection module of the present invention;
FIG. 6 is a waveform diagram of a compensation capacitor input according to the present invention;
FIG. 7 is a waveform diagram of a compensation capacitor cut-out of the present invention;
FIG. 8 is a flowchart of a compensation capacitor switching method according to an embodiment of the invention.
Detailed Description
The conception, specific structure, and technical effects produced by the present invention will be clearly and completely described below with reference to the embodiments and the drawings to fully understand the objects, features, and effects of the present invention. It is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present invention based on the embodiments of the present invention. In addition, all coupling/connection relationships mentioned herein do not refer to direct connection of the components, but rather, refer to the fact that a more optimal coupling structure may be formed by adding or subtracting coupling aids depending on the particular implementation. The technical features in the invention can be interactively combined on the premise of no contradiction and conflict.
Referring to fig. 1, the present invention provides an intelligent capacitance compensation device, which aims at the technical problem that the current or arc phenomenon occurs in the switching process of the compensation capacitance due to the over mechanization of the existing capacitance compensation device.
The invention creates an intelligent capacitance compensation device which comprises an intelligent measurement and control unit, a capacitance switching switch, a controller and a compensation capacitance, wherein the intelligent measurement and control unit is mainly used for collecting electric parameters of a power grid system and calculating a power factor of the power grid system during operation, and the capacitance switching switch is used for detecting a zero-crossing signal of an input voltage of the power grid system and realizing switching operation of the compensation capacitance. The invention mainly intelligently controls the switching quantity of the compensation capacitors in the power grid system according to the power factor of the power grid system, and when the intelligent measurement and control unit detects that the power factor of the power grid system is too low, the compensation capacitors are input, so that even if the power grid system fluctuates, the invention can also adjust according to the current running condition of the power grid system; moreover, the capacitor switching switch can detect the zero-crossing signal of the input voltage and current of the power grid system, so that the switching operation of the compensation capacitor on the zero-crossing signal of the voltage and current can be performed, the phenomena of arc and inrush current are avoided as in the traditional capacitor compensation device, and the service life of the device is prolonged.
Referring to fig. 3, in the invention, the intelligent measurement and control unit is in communication connection with the controller, the output end of the controller is connected with the capacitor switching switch, the intelligent measurement and control unit, the capacitor switching switch and the compensation capacitor are installed and fixed in an insulation box 1, the separated structure of the traditional capacitor compensation device is changed, the installation and maintenance are convenient, a plurality of heat dissipation holes 2 are formed in the top of the insulation box 1, the heat dissipation of the compensation capacitor is facilitated, the service life of the compensation capacitor is prolonged, an air circuit breaker 3 is simultaneously arranged in the top of the insulation box 1, and the connection between the device and a power grid system can be rapidly cut off when an accident occurs, so that the device is prevented from being damaged.
Referring to fig. 2, specifically, the capacitor switching switch in the invention includes a detection circuit and a magnetic latching relay for implementing the switching operation of the compensation capacitor, where the detection circuit includes a voltage transformer, a current transformer and an anti-impact capacitor, the input end of the voltage transformer, the input end of the current transformer and the anti-impact capacitor are connected in series, the output end of the voltage transformer and the output end of the current transformer are respectively connected with the input end of the controller, and the input end of the magnetic latching relay is connected with the output end of the controller, and the connection is not direct, but can be indirectly connected with the input end of the controller through an analog-digital conversion circuit and a voltage-reducing current-limiting circuit. The voltage transformer and the current transformer are respectively used for detecting the voltage and current values input by the power grid system, and when the overvoltage input phenomenon occurs in the power grid system, the anti-impact capacitor can play a role in protection, and the property that the voltages at the two ends of the capacitor cannot be suddenly changed is utilized; the magnetic latching relay is consistent with the working principle of a general relay, but when the magnetic latching relay is switched in the switching state, a pulse electric signal with a certain width is required to be added into the input end, and the magnetic latching relay has stronger current carrying capacity than the general relay, has smaller volume and saves occupied space.
Further as a preferred embodiment, the intelligent measurement and control unit comprises an acquisition chip, and the model of the acquisition chip is CS5460A. The acquisition chip with the model CS5460A is mainly used for acquiring electric parameters of a power grid system and mainly comprises voltage and current effective values input by each phase of the power grid system, the acquisition chip has the functions of measurement and calculation, and an analog-to-digital converter and an arithmetic unit are arranged in the acquisition chip, so that the intelligent measurement and control unit does not need to use intelligent chips such as a controller, the cost is effectively reduced, and the design is simplified.
Further as a preferred embodiment, the invention provides a fault protection mechanism, and the device comprises a protection unit, wherein the protection unit comprises a temperature detection module and a phase failure detection module, the output end of the temperature detection module is connected with the input end of the controller, and the phase failure detection module is connected with the input end of the magnetic latching relay; the temperature detection module is used for collecting the current temperature of the compensating capacitor which is input, and when the temperature of the compensating capacitor is too high, the controller controls the magnetic latching relay to cut off the compensating capacitor, so that the explosion phenomenon of the compensating capacitor caused by the too high temperature is prevented; the phase failure detection module is used for detecting whether a power failure and phase failure condition occurs in the power grid system, when the power failure and phase failure condition occurs in the power grid system, the magnetic latching relay is directly controlled to cut off all compensation relays, and the existing capacitance compensation device lacks a phase failure detection function, so that switching of compensation capacitance can be continuously carried out even if the phase failure condition occurs in the applied power grid system, unpredictable fluctuation occurs in the power grid system, and various unpredictable consequences are brought to electric equipment in the power grid system.
Further as preferred implementation mode, temperature detection module includes model STLM75 temperature sensor, temperature sensor can be directly with temperature signal's form output to the controller input, and the controller of being convenient for handles, be connected through I2C (integrated circuit bus) between temperature sensor and the controller, reduce the wiring number of temperature sensor and the controller, the temperature sensor detection resolution of this model is high simultaneously, and detection range is wide.
Referring to fig. 4, as a further preferred embodiment, the open-phase detection module includes a single-phase power supply sampling circuit, a reference power supply, a comparison circuit, a discharge circuit and a trigger circuit, where an input end of the single-phase power supply sampling circuit is connected to a single-phase power supply interface, an output end of the single-phase power supply sampling circuit is connected to an input end of the comparison circuit, a signal input interface is connected to an input end of the reference power supply, an output end of the reference power supply is connected to the single-phase power supply sampling circuit and the comparison circuit, an output end of the comparison circuit is connected to an input end of the trigger circuit and an input end of the discharge circuit, and the capacitor switching switch is connected to the discharge circuit and the trigger circuit. The signal input interface comprises a live wire zero line and a power supply end, and the voltage of the power supply end is converted into a voltage suitable for supplying power to each module of the circuit through a reference power supply. The specific working principle is as follows: the single-phase power supply sampling circuit is used for sampling the electric parameters of the single-phase power supply, and is used as a basis for judging whether the single-phase power supply fails or not, then the sampled electric parameters are input into the comparison circuit and are compared with preset parameters, and according to the obtained result, the work of the trigger circuit and the discharge circuit can be controlled in time when the single-phase power supply fails, and the connection of the capacitor switching circuit is cut off.
Referring to fig. 5, the single-phase power sampling circuit specifically includes a rectifier bridge U1 and a first optocoupler B1, where an input end of the rectifier bridge U1 is connected to the single-phase power interface, an output end of the rectifier bridge U1 is connected in parallel with an electrolytic capacitor C3 and a first voltage stabilizing tube ZD1, an output end of the rectifier bridge U1 is connected to an input end of the first optocoupler B1, and an output end of the first optocoupler B1 is connected to an input end of the comparison circuit. The rectifier bridge U1 is used for converting alternating current into direct current, the electrolytic capacitor C3 plays a role in filtering, the first voltage stabilizing tube ZD1 can play a role in voltage clamping, when the input voltage is too high, the first voltage stabilizing tube ZD1 breaks down reversely, the potentials at two ends are limited at a fixed value, the damage of a subsequent circuit is prevented, the first optocoupler B1 mainly plays a role in isolation and sampling, and the voltage at two ends of the input end of the first optocoupler B1 is too high and is not suitable for processing of the subsequent circuit, so that the single-phase power supply sampling circuit isolates and converts the input electric signal by using the first optocoupler B1, and the subsequent circuit processing is facilitated.
Further, the reference power supply comprises a three-terminal voltage stabilizer U2, capacitors are respectively connected between the input end of the three-terminal voltage stabilizer U2 and the ground end, between the output end of the three-terminal voltage stabilizer U2 and the ground end in parallel, the input end of the three-terminal voltage stabilizer U2 is connected with the signal input interface, and the output ends of the three-terminal voltage stabilizer are respectively connected with the single-phase power supply sampling circuit and the comparison circuit. The model of the three-terminal voltage stabilizer U2 is 78L05, the three-terminal voltage stabilizer U2 can convert the voltage of an input end into another stable voltage value and output the voltage value, and a first capacitor C1 and a second capacitor C2 are respectively connected between the input end and the grounding end and between the output end and the grounding end of the three-terminal voltage stabilizer U2 in parallel, so that the purpose of filtering high-frequency electric signals of the input end and the output end is achieved.
Further, the comparison circuit comprises a comparator integrated chip U3 and an NPN triode Q1, a first comparator and a second comparator are integrated in the comparator integrated chip U3, the output end of the first comparator and the output end of the second comparator are respectively connected to the cathodes of a first diode D1 and a second diode D2, the anodes of the first diode D1 and the second diode D2 are connected and are connected with the base electrode of the triode Q1 through a second voltage stabilizing tube ZD2, the collector electrode of the triode Q1 is connected with the input end of the trigger circuit, and the output end of the second comparator is also connected with the input end of the power generation circuit. The comparison circuit is the most critical part in the open-phase detection module, mainly plays a role in judgment and control, and is used for comparing the electric signal input by the single-phase power supply sampling circuit with preset parameters to obtain a result which is used for controlling the operation of the discharge circuit and the trigger circuit and controlling the connection or non-connection of the capacitor switching circuit according to a compared structure.
Further, the comparison circuit further comprises a first Light Emitting Diode (LED) 1 and a second Light Emitting Diode (LED) 2, wherein the cathode of the first Light Emitting Diode (LED) 1 is connected with the output end of the first comparator, and the cathode of the second Light Emitting Diode (LED) 2 is connected with the collector of the triode Q1. The open-phase detection module is also provided with an external prompt function, the prompt function is realized by utilizing the first light-emitting diode LED1 and the second light-emitting diode LED2, and different light-emitting diodes can be correspondingly lightened under the conditions of normal and fault of the single-phase power supply so as to represent whether the single-phase power supply is normal or not.
Further, the model of the comparator integrated chip U3 is LM393. The comparator integrated chip U3 of the model is internally integrated with two comparators, so that the integration level is high, and the circuit structure is effectively simplified.
Further, the discharging circuit includes a plurality of second optocouplers B2, the triggering circuit includes a plurality of third optocouplers B3, an output end of the second comparator is connected to an input end of the second optocouplers B2 of the discharging circuit, a collector of the triode Q1 is connected to an input end of the third optocouplers B3 of the triggering circuit, and the second optocouplers B2 and the third optocouplers B3 also play an isolating role.
Referring to fig. 8, a method for switching the capacitor of the intelligent capacitor compensation device includes the following steps:
step A: setting an input threshold and a cut-off threshold of a compensation capacitor, wherein the input threshold is smaller than the cut-off threshold, setting reactive power limit values of a power grid system under different apparent powers, and setting a detection period;
and (B) step (B): starting timing, wherein the timing time corresponds to the detection period;
step C: collecting electric parameters in a power grid system, and calculating the power factor, apparent power and reactive power of the power grid system, wherein the power factor and the reactive power are calculated by a collecting chip CS 5460A;
step D: judging whether the power factor of the power grid system is larger than 0 and smaller than an input threshold, if so, inputting a group of compensation capacitors, judging whether the power factor of the power grid system is larger than an ablation threshold or smaller than 0, and if so, cutting off one compensation capacitor; if the power factor of the power grid system is larger than the input threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, inputting a group of compensation capacitors, if the power factor of the power grid system is smaller than the cutoff threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, cutting off a group of compensation capacitors;
Step E: and (5) waiting for the end of the timing, and returning to the step B.
The method for switching the capacitor is characterized in that the power factor and the reactive power of the power grid system are periodically and repeatedly detected and calculated in general, and the switching quantity of the compensation capacitor is controlled according to specific values of the power factor and the reactive power, so that the power factor of the power grid system is adjusted, and the reactive power of the power grid system is reduced. In the step A, basic parameters including an input threshold, an ablation threshold, reactive power limit values under different apparent powers of a power grid system and a detection period are firstly required to be set, wherein the input threshold is smaller than the ablation threshold, the input threshold and the ablation threshold divide a system power factor into 3 sections, and the power factor is between-1 and 1.
The switching operation of the compensation capacitor is controlled according to the power factor and the reactive power of the power grid system, and when the power factor is larger than 0 and smaller than a switching threshold, the power factor of the power grid system is too low, and the compensation capacitor is required to be switched in no matter what the reactive power value is; when the power is smaller than 0 or larger than the cut-off threshold, the absolute value of the power factor of the power grid system is too low, and the compensation capacitor needs to be cut off no matter what the reactive power is; when the power factor is larger than the input threshold, the current apparent power and reactive power of the power grid system need to be detected, because when the apparent power of the power grid system is higher, the reactive power of the power grid system is larger although the power factor is larger than the input threshold, and excessive electric quantity can be lost by the power grid system, therefore, the invention needs to detect the apparent power and the reactive power of the power grid system, judge whether the reactive power is larger than a set reactive power limit value, if the reactive power is larger than the set reactive power limit value, then the compensation capacitor needs to be input, and similarly when the power factor is smaller than the cut-off threshold, the compensation capacitor needs to be cut off if the reactive power is larger than the set reactive power limit value. In addition, the control method is compromised in that different reactive power limit values are required to be set according to different apparent powers when the reactive power limit values are set, and the reactive power limit values and the apparent powers are positively correlated.
The detection period in the step A is the switching operation delay time of the device, and is mainly used for avoiding the switching operation of the compensation capacitor of the device from being too frequent, so that the power grid system generates larger fluctuation; step C and step D are specific switching control processes of the compensation capacitor, firstly, electric parameters in the power grid system are collected, the electric parameters are input into a collection chip CS5460A to calculate power factors, apparent power and reactive power of the power grid system, if the power grid system is three-phase power input, the power factors, apparent power and reactive power of each phase are required to be calculated at the same time, and then corresponding switching operation of the compensation capacitor is carried out on each phase input.
Further, as an optimized implementation manner, the invention further comprises a step F in the capacitive switching control process, wherein the step F can be arranged at any position after the step A, namely, the device performs related processing immediately as long as one operation condition is disqualified in the operation process. The capacitance compensation device in the embodiment of the invention needs to detect a plurality of operation conditions, including detecting the temperature of the compensation capacitance, detecting whether the power failure and phase failure phenomenon exists in the power grid system, detecting the voltage at two ends of the compensation capacitance and detecting the input current of the power grid system, so that a plurality of reference parameters including the maximum temperature limit value, the overvoltage protection threshold and the under-current blocking threshold which allow the compensation capacitance to operate are additionally arranged in the step A. The step F comprises the following steps:
f01: collecting the current temperature of the compensation capacitor, and cutting off the compensation capacitor if the current temperature of the compensation capacitor is greater than a temperature limit value;
f02: judging whether the power grid system is powered off, if so, cutting off all compensation capacitors;
f03: judging whether the voltage at two ends of the compensation capacitor is larger than an overvoltage protection threshold, and if so, cutting off the compensation capacitor;
F04: and judging whether the input current of the power grid system is smaller than an under-current blocking threshold, and if so, stopping the switching operation of the compensation capacitor.
Of course, the sequence of the steps is not limited to the embodiment, and the person skilled in the art can make corresponding changes in the sequence based on the steps.
Specifically, in step F01, the temperature of the compensating capacitor that has been put into is detected by using the temperature detection module, the temperature is an important parameter that affects whether the capacitor can be used normally, if the temperature of the compensating capacitor is too high, the service life of the compensating capacitor is easily reduced, and meanwhile, the probability of explosion of the compensating capacitor in the use process is also improved; in the step F02, the phase interruption detection module is utilized to detect the phase interruption and phase interruption phenomenon of the power grid system, and the existing capacitance compensation device still performs switching operation of the compensation capacitance when the phase interruption and phase interruption situation occurs due to the lack of detection of the phase interruption and phase interruption phenomenon, so that the power grid system has unpredictable fluctuation and has great influence on electric equipment in the power grid system; in the step F03, the voltages at two ends of the input compensation capacitor are detected, and when the voltages at two ends of the compensation capacitor are too high, the explosion of the compensation capacitor is possibly caused; in step F04, it is determined whether the input current of the power grid system is smaller than the undercurrent blocking threshold, so that when the input current is low, it is proved that the power grid system is not connected to any load, and therefore switching operation of the compensation capacitor is not needed.
Further as a preferred embodiment, the present invention creates the specific input or cut-out operation of the compensation capacitor in the step D as follows: collecting a voltage and current instantaneous value of an input end of a power grid system; if the compensation capacitor is put into operation, adding a first pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input voltage, so that the compensation capacitor can be put into operation at the zero crossing point of the input voltage; if the compensation capacitor cutting operation is needed, adding a second pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input current, so that the compensation capacitor can know that the zero crossing point of the input current is cut; the first pulse electric signal and the second pulse electric signal have the same amplitude and opposite polarities, and the pulse width of the first pulse electric signal and the second pulse electric signal is larger than 1/4 period of the input voltage and the input current.
Based on the step D, the device can realize the zero-crossing switching function of the compensation capacitor so as to avoid the occurrence of arc or inrush current. Referring to fig. 6 and fig. 7, specifically, when the compensation capacitor input operation is performed, the voltage transformer detects an instantaneous value of the input voltage of the power grid, and a first pulse electric signal is added to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input voltage, so that the output end of the magnetic latching relay is closed at the zero crossing point of the input voltage, the compensation capacitor input operation is completed, and the inrush current phenomenon is avoided; when the compensation capacitor cutting operation is carried out, the current transformer detects the instantaneous value of the input current of the power grid, and then a second pulse electric signal is added to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input current, so that the output end of the magnetic latching relay is disconnected at the zero crossing point of the input current, the compensation capacitor cutting operation is completed, and the arcing phenomenon is avoided. The first pulse electric signal and the second pulse electric signal have the same amplitude and opposite polarity, and the specific signal is positive and the specific signal is negative, and the pulse width of the first pulse electric signal and the second pulse electric signal is larger than 1/4 period of the input voltage and the input current depending on the peripheral circuit structure.
Of course the compensation capacitor investment and the cut-off operation in other steps are similar.
Referring to fig. 8, a specific embodiment of a capacitor switching method of an intelligent capacitor compensation device of the present invention includes the following steps:
s01: setting an input threshold, a cutting threshold and a detection period of the compensation capacitor;
s02: setting a maximum temperature limit value, an overvoltage protection threshold and an under-current blocking threshold;
S03: starting timing;
S04: judging whether the temperature of the added compensation capacitor is greater than a temperature limit value, and if so, cutting off the compensation capacitor;
S05: judging whether the power grid system has the phenomenon of power failure and phase failure, and if so, cutting off all compensation capacitors;
S06: judging whether the voltage at two ends of the input compensation capacitor is larger than an overvoltage protection threshold, and if so, cutting off the compensation capacitor;
s07: judging whether the input current of the power grid system is smaller than an under-current blocking threshold, and if so, stopping switching operation of the compensation capacitor;
s08: collecting electric parameters of a power grid system, calculating a power factor, and collecting an input voltage and current instantaneous value of the power grid system;
S09: if the power factor is larger than 0 and smaller than the input threshold, adding a first pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input voltage, wherein a plurality of power factors are smaller than 0 or larger than the cutting threshold, adding a second pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input current, and otherwise, no operation is needed;
S10: the waiting timing ends, and the process advances to step S03.
While the preferred embodiment of the present application has been described in detail, the application is not limited to the embodiments, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the application, and these modifications and substitutions are intended to be included in the scope of the present application as defined in the appended claims.
Claims (1)
1. The utility model provides a capacitance switching method of intelligent capacitance compensation device, characterized in that is applied to an intelligent capacitance compensation device, the device includes:
And an intelligent measurement and control unit: the power factor calculating device is used for detecting the electric parameters of the power grid system and calculating the power factor of the power grid system;
a capacitive switching switch: the switching operation is used for executing the compensation capacitor;
a controller and a compensation capacitor;
The intelligent measurement and control unit is in communication connection with the controller, the output end of the controller is connected with the capacitor switching switch, the intelligent measurement and control unit, the capacitor switching switch and the compensation capacitor are installed and fixed in the insulation box, the capacitor switching switch comprises a detection circuit and a magnetic latching relay for controlling the switching of the compensation capacitor, the detection circuit is connected between a live wire and a zero line in series, the detection circuit comprises a voltage transformer, a current transformer and an anti-impact capacitor, the input end of the voltage transformer, the input end of the current transformer and the anti-impact capacitor are connected in series, the output end of the voltage transformer and the output end of the current transformer are respectively connected with the input end of the controller, and the input end of the magnetic latching relay is connected with the output end of the controller;
The intelligent measurement and control unit comprises an acquisition chip, wherein the model of the acquisition chip is CS5460A;
the protection unit comprises a temperature detection module and a phase failure detection module, wherein the output end of the temperature detection module is connected with the input end of the controller, and the phase failure detection module is connected with the input end of the magnetic latching relay;
the top of the insulating box is provided with a heat dissipation hole and an air circuit breaker, and the air circuit breaker is used for cutting off the connection between the device and a power grid system;
The method comprises the following steps:
step A: setting an input threshold and a cut-off threshold of a compensation capacitor, wherein the input threshold is smaller than the cut-off threshold, setting reactive power limit values of a power grid system under different apparent powers, and setting a detection period;
and (B) step (B): starting timing, wherein the timing time corresponds to the detection period;
step C: collecting electric parameters in a power grid system, and calculating the power factor, apparent power and reactive power of the power grid system, wherein the power factor and the reactive power are calculated by a collecting chip CS 5460A;
step D: judging whether the power factor of the power grid system is larger than 0 and smaller than an input threshold, if so, inputting a group of compensation capacitors, judging whether the power factor of the power grid system is larger than an ablation threshold or smaller than 0, and if so, cutting off one compensation capacitor; if the power factor of the power grid system is larger than the input threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, inputting a group of compensation capacitors, if the power factor of the power grid system is smaller than the cutoff threshold, judging whether the reactive power of the power grid system is larger than the reactive power limit value under the current apparent power condition, if so, cutting off a group of compensation capacitors;
step E: b, waiting for the end of timing, and returning to the step B;
in the step A, the highest temperature limit value, the overvoltage protection threshold and the under-current lockout threshold of the compensation capacitor which are allowed to run are also required to be set;
The method further comprises a step F, wherein the running condition of the capacitance compensation device is detected automatically, and the step F can be arranged at any position after the step A;
the step F comprises the following steps:
f01: collecting the current temperature of the compensation capacitor, and cutting off the compensation capacitor if the current temperature of the compensation capacitor is greater than a temperature limit value;
f02: judging whether the power grid system is powered off, if so, cutting off all compensation capacitors;
f03: judging whether the voltage at two ends of the compensation capacitor is larger than an overvoltage protection threshold, and if so, cutting off the compensation capacitor;
f04: judging whether the input current of the power grid system is smaller than an under-current blocking threshold, and if so, stopping switching operation of the compensation capacitor;
in the step D, the method further comprises the step of collecting the voltage and current instantaneous value of the input end of the power grid system; if the compensation capacitor is put into operation, adding a first pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input voltage; if the compensation capacitor cutting operation is needed, adding a second pulse electric signal to the input end of the magnetic latching relay at the highest point of the instantaneous value of the input current; the first pulse electric signal and the second pulse electric signal have the same amplitude and opposite polarities, and the pulse width of the first pulse electric signal and the second pulse electric signal is larger than 1/4 period of the input voltage and the input current.
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| CN113036778A (en) * | 2021-03-14 | 2021-06-25 | 德威特智能电气(深圳)有限公司 | Intelligent circuit breaker for impact load current compensation and control method thereof |
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