CN209471196U - A kind of low-voltage electric energy quality detecting system - Google Patents
A kind of low-voltage electric energy quality detecting system Download PDFInfo
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- CN209471196U CN209471196U CN201920072786.6U CN201920072786U CN209471196U CN 209471196 U CN209471196 U CN 209471196U CN 201920072786 U CN201920072786 U CN 201920072786U CN 209471196 U CN209471196 U CN 209471196U
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Abstract
The utility model discloses a kind of low-voltage electric energy quality detecting system, including power grid simulation source, Three-phase harmonic source, idle simulation source, monitoring system, the central controller controlled to system, the host computer being connect with central controller；The utility model uses the low-voltage electric energy quality detecting system being made of power grid simulation source, Three-phase harmonic source, idle simulation source, monitoring system, the adaptability for realizing the normal abnormal characteristic of simulation power supply grid by power grid simulation source and examining sample to power supply grid；Power quality problem present on simulation power supply grid is realized by Three-phase harmonic source and idle simulation source, to examine sample to the compensation ability of power quality；The security monitoring to system is realized by monitoring system；The system has many advantages, such as strong antijamming capability, operation stability are high, data test is accurate and reliable, the speed of service is fast, work efficiency is high, wiring is simple and operation is convenient, operational process is safe.
Description
Technical Field
The utility model relates to a detecting system especially relates to a low pressure electric energy quality detecting system.
Background
In recent years, with the rapid development of power grid technology, the demand for diversified power utilization is continuously increased, and the large amount of intermittent distributed energy is accessed, so that the complexity of user-side equipment is higher and higher, the power quality becomes a main problem concerned by modern social power utilization manufacturers, and in order to improve the power quality, enterprises can use power compensation equipment in a power grid, so that the inspection of the compensation characteristics of the power compensation equipment is particularly important. Due to the fact that a plurality of power quality problems exist in a power supply grid, abnormal operation phenomena such as voltage sag, flicker, frequency fluctuation, harmonic interference and instantaneous overload easily occur, aging, failure and interference of severe environments of components are inevitable to occur in the long-time operation process of power quality detection system equipment, the fault rate of the system equipment is increased, the measurement accuracy is reduced, or invalid abnormal data are generated, the overall reliability of the system equipment is reduced, and therefore the three-phase imbalance problem and the grid harmonic problem are increasingly serious. At present, the main shortcomings of the existing low-voltage power quality detection system are as follows: on one hand, due to the lack of an effective power factor compensation mechanism or unreasonable power factor compensation setting, an under-compensation phenomenon and an over-compensation phenomenon are easily generated, so that system equipment cannot play due functions, electric equipment is damaged, even the safety of the system equipment and other electric facilities is endangered, and the service life of the system equipment is greatly shortened; on the other hand, due to the unreasonable design of a three-phase harmonic source and reactive compensation, the problems of voltage fluctuation flicker, voltage sag and rise, serious three-phase imbalance and the like easily caused by nonlinear load and impact load connected into a power grid system cannot be ensured, the accuracy and reliability of control logic cannot be ensured, the accurate control of harmonic frequency and amplitude is difficult to realize, the low-voltage power quality detection system equipment is easy to have abnormal operation state, and even the system is easy to have potential safety hazards such as failure, fire and the like, so that the alarm cannot be given in time; in addition, the problems of complex design, poor parallel capacity expansion capability, low operation stability, low data test accuracy, complex wiring, complex operation, unsafe operation process and the like exist.
SUMMERY OF THE UTILITY MODEL
The utility model solves the technical problem of overcoming the defects of the prior art and providing a low-voltage power quality detection system which comprises a power grid analog source, a three-phase harmonic source, a reactive analog source and a monitoring system, realizes the simulation of the normal abnormal characteristics of a power supply power grid through the power grid analog source and tests the adaptability of a tested sample to the power supply power grid; the problem of electric energy quality existing on a power supply network is simulated through a three-phase harmonic source and a reactive simulation source so as to check the compensation capability of a tested sample on the electric energy quality; the safety monitoring of the system is realized through the monitoring system; and the PWM controller is used for controlling the harmonic voltage which is simultaneously output by the three-phase harmonic generation module and superposed by various frequencies, so that the independent control of PWM rectification and inversion is realized, the accuracy and the reliability of control logic are further ensured, the accurate control of harmonic times and amplitude is realized, and the potential safety hazard in the operation process of the system is reduced.
In order to solve the technical problem, the utility model discloses a following technical scheme can solve:
a low-voltage power quality detection system comprises a power grid simulation source, a three-phase harmonic source, a reactive simulation source, a monitoring system, a central controller and an upper computer, wherein the power grid simulation source is used for simulating normal and abnormal characteristics of a power supply grid and testing the adaptability of a tested sample to the power supply grid, the three-phase harmonic source is used for outputting harmonic voltage, the reactive simulation source is used for providing a reactive compensation signal, the monitoring system is used for monitoring the system, the central controller is used for controlling the system, the upper computer is connected with the central controller, the power grid simulation source is connected with the power supply grid, the tested sample is connected with the power grid simulation source through a first transformer, the three-phase harmonic source and the reactive simulation source are connected with the tested sample in parallel through a third transformer, and the power grid simulation source, the three-phase harmonic source, the reactive simulation source, the first transformer, the tested sample and the upper computer. The normal and abnormal characteristics of a power supply grid are simulated through a grid simulation source, and the adaptability of a tested sample to the power supply grid is checked; the problem of electric energy quality existing on a power supply network is simulated through a three-phase harmonic source and a reactive simulation source so as to check the compensation capability of a tested sample on the electric energy quality; the safety monitoring of the system is realized through the monitoring system.
Preferably, the power grid analog source is connected with a current detection module for sampling current of the power grid analog source and a voltage detection module for sampling voltage of the power grid analog source, and the current detection module and the voltage detection module are respectively connected to the central controller through a power factor compensation circuit. Through the arrangement of the power factor compensation circuit, the power factor can reach 0.95, the harmonic current content is lower than 3% FS, and the interference to a power supply grid is small; the dynamic power factor compensation is carried out on the tested sample through the power factor compensation circuit, so that the adaptability of the tested sample to the power supply grid can be tested, and the detection of the normal and abnormal characteristics of the power supply grid is realized.
Preferably, the power factor compensation circuit comprises a regulated power supply, a power factor compensation main circuit, a PWM pulse modulation and drive control circuit, and a phase current and voltage detection and comparison circuit, which are connected with each other, the regulated power supply supplies power to the circuit, the power factor compensation main circuit comprises a first filter inductor, a second filter inductor, a first filter capacitor, a second filter capacitor, a third filter capacitor, a charge and discharge capacitor, an absorption capacitor, a coupling capacitor, a second transformer, a current detection resistor, a first voltage detection resistor, a second voltage detection resistor, a first power switch element, and a second power switch element, one end of the first filter inductor is connected with an input end L of alternating current, the other end of the first filter inductor is connected with one end of the charge and discharge capacitor, the first voltage detection resistor, and the current detection resistor, the other end of the charge and discharge capacitor is connected with one end of a primary winding N1 of the second transformer, the other end of the primary winding N1 of the second transformer is connected with a first power switching element and a second power switching element which are connected in parallel, the cathode of the first power switching element and the anode of the second power switching element are connected to the common end N of the alternating current, and the cathode and the driving electrode of the first power switching element and the second power switching element are respectively connected to a first driving circuit and an isolation driving circuit of the PWM pulse modulation and driving control circuit; one end of the first filter capacitor is connected to an input end L of the alternating current, and the other end of the first filter capacitor is connected with a common end N of the alternating current; one end of the second filter capacitor is connected with the first filter inductor, and the other end of the second filter capacitor is connected to a common end N of the alternating current; the other end of the first voltage detection resistor is respectively connected with a voltage detection circuit of the phase current voltage detection and comparison circuit and one end of a second voltage detection resistor, and the other end of the second voltage detection resistor is connected to a common end N of the alternating current; the other end of the current detection resistor is connected to an output end LM of the alternating current through a second filter inductor; the absorption capacitor is connected with the secondary winding N2 of the second transformer in parallel, one end of the absorption capacitor is connected with the output end LM of the alternating current, the other end of the absorption capacitor is connected with one end of the coupling capacitor, and the other end of the coupling capacitor is connected with the common end N of the alternating current; one end of the third filter capacitor and one end of the sample to be measured are respectively connected with the output end LM of the alternating current, and the other ends of the third filter capacitor and the sample to be measured are respectively connected with the common end N of the alternating current. When the power factor compensation circuit works, alternating current AC is input at an input end L and a common end N of the power factor compensation main circuit, the alternating current AC is supplied to a circuit consisting of a charging and discharging capacitor, a primary winding N1 of a second transformer, a first power switching element and a second power switching element through a first filter capacitor, a first filter inductor and a second filter capacitor, and then is supplied to a sample to be detected after being filtered by a second filter inductor and a third filter capacitor through a current detection resistor;
specifically, a voltage detection circuit of the phase current and voltage detection and comparison circuit detects the terminal voltage of a detected sample after voltage division is carried out by a first voltage detection resistor and a second voltage detection resistor in a power factor compensation main circuit; the current detection circuit detects the current flowing through the detected sample through the current detection resistor, processes the detected voltage and current waveforms, transmits the processed voltage and current waveforms to the current and voltage comparison circuit for comparison, controls the PWM pulse modulation circuit in the PWM and drive control circuit to control the drive circuit and the isolation drive circuit through control voltage, and respectively controls the switching of the first power switch element and the second power switch element; the voltage waveform detected by the voltage detection circuit is processed by the phase detection circuit and then transmitted to a phase and automatic power factor control circuit in the PWM pulse modulation and drive control circuit, the switching-on and switching-off sequence of a first power switching element and a second power switching element is controlled by the phase and automatic power factor control circuit through the PWM pulse modulation circuit, a first drive circuit and an isolation drive circuit, a charge-discharge capacitor is subjected to pulse charging in a 0-pi/2 period by a primary winding N1 of a second transformer, and the charge-discharge capacitor is subjected to pulse discharging in a 3 pi/2-2 pi period; carrying out pulse type discharge on the charge and discharge capacitor in a pi/2-pi period, and carrying out pulse type charge on the charge and discharge capacitor in a pi-3/2 pi period; when the power factor is lower than 1, the current and voltage comparison circuit in the phase current and voltage detection and comparison circuit outputs a constant voltage to control a PWM pulse modulation circuit in the PWM pulse modulation and driving control circuit, the first driving circuit and the isolation driving circuit respectively control the on-off time of the first power switching element and the second power switching element, and further control the on-off time of a primary winding N1 of the second transformer and the charging and discharging capacitor; when the alternating current is switched on and off in a pulse mode within the periods of 0-pi/2 and pi-3/2 pi, the first power switch element and the second power switch element adjust the charging quantity of the charge and discharge capacitor by adjusting the PWM pulse width, namely the on-off time; when the pulse is switched on and off in the periods of the alternating current pi/2-pi and 3/2 pi-2 pi, the first power switch element and the second power switch element adjust the discharge capacity of the charge-discharge capacitor by adjusting the PWM switching-on and switching-off time; the adjustment of the charge and discharge amount of the compensation charge and discharge capacitor is equivalent to the adjustment of the capacitance value of the compensation charge and discharge capacitor, so that dynamic compensation is realized; when the first power switch element and the second power switch element are respectively conducted, electric energy is stored in the first filter inductor when current passes through the first filter inductor, the charge-discharge capacitor and the primary winding N1 of the second transformer, and at the moment of switching off, the electric energy stored in the first filter inductor is released after being filtered by the second filter inductor and the third filter capacitor, so that power factor correction is carried out on a tested sample; on the other hand, the electric energy stored in the second transformer is discharged through the secondary winding N2, the absorption capacitor, and the coupling capacitor, and the power factor of the sample to be measured is corrected again.
Preferably, the three-phase harmonic source comprises a detection module, a harmonic generator for outputting harmonic voltage, and a PWM controller for controlling the voltage frequency and amplitude of the harmonic voltage output by the harmonic generator, wherein the harmonic generator is connected with the PWM controller, and the PWM controller is connected with an upper computer; the harmonic generator comprises a first communication module, a relay output module, an analog quantity output module and a three-phase harmonic generation module, wherein the input end of the detection module is connected with a power supply grid, the output end of the detection module is connected with an upper computer, the upper computer is respectively connected with the input end of the relay output module and the input end of the analog quantity output module through the first communication module, the output end of the relay output module and the output end of the analog quantity output module are respectively connected with the three-phase harmonic generation module, and the three-phase harmonic generation module is connected with the power supply grid; the three-phase harmonic source is used for outputting harmonic voltage, the three-phase harmonic source can output 2-50 times of higher harmonics of three-phase harmonics, multiple sets of harmonic sources can be operated in parallel, the capacity of parallel capacity expansion is achieved, and the three-phase harmonic source has the advantages of being strong in anti-interference capacity, high in operation stability, accurate and reliable in data test, high in operation speed, high in working efficiency, simple in wiring, convenient to operate, safe in operation process and the like.
The utility model discloses an in, the sample of being surveyed is connected on harmonic generator through the third transformer, and the third transformer carries out voltage transformation and transmission electric energy to the harmonic voltage of harmonic generator output, has improved the adaptability of three-phase harmonic source at the sample of being surveyed to electric energy quality's compensation ability in-process.
Preferably, the three-phase harmonic generation module comprises an A-phase harmonic generation module, a B-phase harmonic generation module and a C-phase harmonic generation module which are completely the same in structure, the A-phase harmonic generation module, the B-phase harmonic generation module and the C-phase harmonic generation module are respectively provided with a three-phase harmonic generation circuit, the three-phase harmonic generation circuit comprises a state monitor, an alternating current contactor, a relay, a monotonic harmonic elimination circuit, a high-pass harmonic elimination circuit and an anti-parallel thyristor, the input end of the state monitor is connected with a power supply grid through a circuit breaker, the output end of the state monitor is connected with one end of a relay contact through the alternating current contactor, the other end of the relay contact is connected with one end of the monotonic harmonic elimination circuit or the high-pass harmonic elimination circuit, the other end of the monotonic harmonic elimination circuit or the high-pass harmonic elimination circuit is connected with one end, the trigger signal input end of the anti-parallel thyristor is connected with the analog quantity output module, the coil of the relay is connected with the relay output module, and the communication port of the state monitor is connected with the first communication module. The state monitor is mainly used for realizing the state monitoring, the interlocking function and the detection of zero-crossing signals of all branches, and ensuring the correct attraction and inrush-free switching of the relay and the alternating current contactor.
The utility model discloses an in, monotonous harmonic elimination circuit includes series connection's first resistance, first reactor, first condenser.
The utility model discloses an in, high pass harmonic elimination circuit includes second resistance, second reactor, second condenser, third condenser, and the third condenser forms the branch road that connects in parallel with the second reactor again after establishing ties with the second resistance, and the branch road that connects in parallel establishes ties with the second condenser again.
The utility model discloses an in, three-phase harmonic generation module is equipped with the preceding wave filter that connects gradually, harmonic power module, back filter, harmonic power module is including the PWM rectifier that is used for establishing stable direct current voltage, direct current side energy storage electric capacity, the PWM dc-to-ac converter that is used for generating given voltage signal, PWM rectifier, direct current side energy storage electric capacity, PWM inverter connect gradually, the output of preceding wave filter is connected with the input of PWM rectifier, the output of PWM inverter is connected with back filter, the output of PWM controller is connected with PWM rectifier, PWM inverter respectively; setting and displaying a three-phase current waveform interface, a state monitoring display interface and a harmonic generation frequency setting interface by an upper computer; the three-phase harmonic generation module formed by combining the front filter, the harmonic power module and the rear filter is adopted, and the PWM controller is used for controlling the three-phase harmonic generation module to simultaneously output harmonic voltages with multiple frequencies for superposition, so that the independent control of PWM rectification and inversion is achieved, the accuracy and reliability of control logic are ensured, and the accurate control of harmonic times and amplitude is realized.
Specifically, the front filter and the rear filter both adopt an RLC filtering mode, wherein the front filter and the rear filter both comprise a filter inductor, a filter resistor and a filter capacitor which are connected with each other, the filter inductor is connected in series on the PWM rectifier, and the filter resistor and the filter capacitor are connected in series and then connected in parallel on the PWM rectifier.
Preferably, the PWM controller adopts a single chip microcomputer, the single chip microcomputer is provided with a dual-port parallel port RAM, the dual-port parallel port RAM is provided with a data input port, a data output port, an address input port and an address scanning port, and the data input port and the address input port of the dual-port parallel port RAM are connected to the single chip microcomputer;
preferably, the single chip microcomputer is connected with a first 8-bit parallel port analog-to-digital converter and a second 8-bit parallel port analog-to-digital converter which are used for regulating the amplitude, a data port of the first 8-bit parallel port analog-to-digital converter and a data port of the second 8-bit parallel port analog-to-digital converter are both connected with the single chip microcomputer, and a REF port of the first 8-bit parallel port analog-to-digital converter and a REF port of the second 8-bit parallel port analog-to-digital converter are connected with the output of the reference module;
preferably, the single chip microcomputer is further connected with a third 8-bit parallel port analog-to-digital converter and a fourth 8-bit parallel port analog-to-digital converter which are used for controlling output waveforms, and the third 8-bit parallel port analog-to-digital converter and the fourth 8-bit parallel port analog-to-digital converter are connected to the single chip microcomputer through a data output port of the dual-port parallel port RAM;
preferably, the output ports of the first 8-bit parallel port analog-to-digital converter and the second 8-bit parallel port analog-to-digital converter are respectively connected with the first operational amplifier array, the output end of the first operational amplifier array is respectively connected with the REF port of the third 8-bit parallel port analog-to-digital converter and the REF port of the fourth 8-bit parallel port analog-to-digital converter, the output ends of the third 8-bit parallel port analog-to-digital converter and the fourth 8-bit parallel port analog-to-digital converter are respectively connected with the second operational amplifier array, and the output end of the second operational amplifier array is connected with the harmonic generator.
The utility model discloses an in, the singlechip with waveform data through data input port and address input port write in dual port and mouthful RAM, establish the waveform table, the address difference of writing in can realize shifting the phase. The single chip microcomputer transmits the high 8 bits and the low 8 bits of the amplitude signal to a first 8-bit parallel port analog-to-digital converter and a second 8-bit parallel port analog-to-digital converter respectively, the first 8-bit parallel port analog-to-digital converter and the second 8-bit parallel port analog-to-digital converter calculate output voltage through a reference module and transmit the output voltage to a first operational amplifier array, the first operational amplifier array transmits an output value to REF ports of a third 8-bit parallel port analog-to-digital converter and a fourth 8-bit parallel port analog-to-digital converter through proportional accumulation, and therefore the amplitude of an output waveform is regulated.
The utility model discloses an in, the singlechip writes into double-port parallel port RAM with the waveform data of output, writes into third 8 bit parallel port analog to digital converter and fourth 8 bit parallel port analog to digital converter with the data of every moment point, and third 8 bit parallel port analog to digital converter and fourth 8 bit parallel port analog to digital converter pass through the reference voltage of the REF mouth of self, calculate output voltage, send the second fortune to put the array to the waveform phase place that the output needs.
The utility model discloses an in, detection module includes current transformer, analog to digital converter, and current transformer's input is connected with the power supply electric wire netting, and current transformer's output is connected with analog to digital converter's input, analog to digital converter's output and host computer connection.
Preferably, the reactive power simulation source is provided with a reactive power generator, the reactive power generator comprises a first reactor for storing energy and filtering high-frequency switch ripple current, a PWM (pulse-width modulation) converter for providing a reactive power compensation signal in a three-phase fully-controlled bridge topology form and a second driving circuit, the first reactor is connected with a power supply grid through a third transformer, the AC side of the PWM converter is connected with the first reactor, the DC side of the PWM converter is connected with the energy storage capacitor, and the PWM converter is connected to the central controller through the second driving circuit; the three-phase harmonic source and the reactive simulation source are connected in parallel with the tested sample through the third transformer, the third transformer performs voltage transformation on harmonic voltage output by the harmonic generator and transmits electric energy, and the adaptability of the three-phase harmonic source in the process of checking the compensation capacity of the tested sample on the electric energy quality is improved; the PWM converter is composed of an insulated gate bipolar transistor, the insulated gate bipolar transistor is driven to generate a compensation current waveform through a voltage space vector modulation technology, and an energy storage capacitor stores direct current energy generated by the insulated gate bipolar transistor; the second driving circuit receives a control signal sent by the central controller, drives a semiconductor power device of the PWM converter and also has a protection function on the semiconductor power device; the reactive simulation source can compensate reactive power, adjust unbalanced three phases and suppress harmonic waves, avoids the problem of mutual interference, can flexibly configure reactive power on line, effectively realizes reasonable compensation of the reactive power, and provides safety guarantee for system equipment installed in extremely limited space.
The utility model discloses an in, harmonic generator establishes in the harmonic source cabinet, the singlechip is established in the harmonic control cabinet, first transformer, the third transformer is established respectively in each transformer cabinet, the electric wire netting simulation source, the harmonic source cabinet, the harmonic control cabinet, reactive simulation source, the transformer cabinet is all established on being surveyed the sample next door, the sample of being surveyed is established on the test jig, the test jig is established on the wall, the test jig is equipped with the wiring frame, the wiring frame is supported by the support frame in the ceiling below, the support frame is fixed to be established on wall or ceiling, the wiring frame is equipped with the wire casing, the cable conductor is buried underground in the wire casing, the electric wire netting simulation source, the harmonic source cabinet, the harmonic control cabinet, reactive simulation source, the transformer cabinet, the sample of being surveyed all is connected with the power supply electric wire netting through the. The mounting structure formed by combining the support frame, the wiring frame and the test frame provides higher stability, firmness and balance capability for mounting and wiring of system equipment, enables the system to be designed compactly and have higher safety, and fully utilizes limited test space.
In the patent of the utility model, the monitoring system comprises an electric energy quality analyzer for detecting the harmonic of a three-phase harmonic source and transmitting the detected harmonic value to a central controller, a temperature sensor for detecting the temperature signal of system equipment, a smoke sensor for detecting the smoke signal of the system equipment, a time monitoring module for monitoring the working state of the system, and an alarm module for alarming the system, wherein the alarm module is connected with an upper computer, and the electric energy quality analyzer, the temperature sensor, the smoke sensor, the time monitoring module and the alarm module are all connected with the central controller; the alarm module comprises a current-voltage alarm module used for sending alarm information to alarm when the current value and/or the voltage value received by the central controller exceed a threshold value, a time alarm module used for sending the alarm information to alarm when the time value received by the central controller exceeds the threshold value, a temperature alarm module used for sending the alarm information to alarm when the temperature value received by the central controller exceeds the threshold value, a smoke alarm module used for sending the alarm information to alarm when the smoke concentration received by the central controller exceeds the threshold value, and a harmonic alarm module used for sending the alarm information to alarm when the harmonic value received by the central controller exceeds the threshold value, wherein the current-voltage alarm module, the time alarm module, the temperature alarm module, the smoke alarm module and the harmonic alarm module are all connected with the central controller.
The utility model discloses an in, monitored control system still includes second communication module, and second communication module is connected with central controller, alarm module respectively, transmits alarm information to the host computer through second communication module.
The utility model discloses an in, monitored control system still includes the data storage module who is connected with central controller, stores alarm information through data storage module, and data storage module also can save low pressure electric energy quality testing data.
The utility model discloses an in, data storage module is connected with central controller including interconnect's database server and disk array, database server, and central controller passes through database server and saves alarm information to disk array, and the host computer reads alarm information from disk array. The technical scheme of the monitoring system is combined with a data storage module formed by combining the database server and the disk array, so that the reliability of the power quality detection system is improved, the integrity and the accuracy of power quality data are improved, different monitoring functions can be set according to monitoring requirements, an evaluation system is established by utilizing the data stored in the database server, the reliability of the low-voltage power quality detection system is reversely deduced according to the quality of the data, the remote reliability evaluation of the low-voltage power quality detection system is realized, the reliability of the system can also be diagnosed and analyzed, and the system is correspondingly overhauled and maintained according to the historical change trend of the reliability evaluation.
The utility model discloses an in, reactive simulation source is equipped with the RS485 interface, and reactive generator passes through the RS485 interface and is connected with central controller.
The utility model discloses an in, first transformer, third transformer are connected with central controller through the RS485 interface respectively.
The utility model discloses owing to adopted above technical scheme, have apparent technological effect: the low-voltage power quality detection system consisting of a power grid simulation source, a three-phase harmonic source, a reactive simulation source and a monitoring system is adopted, the normal and abnormal characteristics of a power supply power grid are simulated through the power grid simulation source, and the adaptability of a detected sample to the power supply power grid is checked; the problem of electric energy quality existing on a power supply network is simulated through a three-phase harmonic source and a reactive simulation source so as to check the compensation capability of a tested sample on the electric energy quality; the safety monitoring of the system is realized through the monitoring system; the dynamic power factor compensation is carried out on the tested sample through the power factor compensation circuit, so that the adaptability of the tested sample to a power supply grid can be tested, the detection on the normal abnormal characteristic of the power supply grid is realized, the harmonic voltage with multiple frequency superposition is simultaneously output by the three-phase harmonic generation module through the PWM controller to be controlled, the independent control of PWM rectification and inversion is realized, the accuracy and the reliability of control logic are further ensured, the accurate control of harmonic times and amplitude is realized, and the potential safety hazard in the running process of a system is reduced; the system has the advantages of strong anti-interference capability, high operation stability, accurate and reliable data test, high operation speed, high working efficiency, simple wiring, convenient operation, safe operation process and the like.
Drawings
Fig. 1 is a schematic block diagram of an embodiment of the low voltage power quality detection system of the present invention.
Fig. 2 is a schematic circuit diagram of an embodiment of the power factor compensation circuit of the present invention.
Fig. 3 is a schematic block diagram of an embodiment of the reactive power generator of the present invention.
Fig. 4 is a schematic circuit diagram of an embodiment of the reactive power generator of the present invention, which is composed of the first reactor and the PWM converter.
Fig. 5 is a schematic block diagram of an embodiment of the present invention, in which a three-phase harmonic source detects a sample to be tested.
Fig. 6 is a schematic block circuit diagram of an embodiment of a three-phase harmonic source according to the present invention.
Fig. 7 is a schematic circuit diagram of an embodiment of the three-phase harmonic generation circuit of the present invention.
Fig. 8 is a schematic circuit diagram of a three-phase harmonic generation module main circuit according to an embodiment of the present invention.
Fig. 9 is a schematic block diagram of the embodiment of the single chip microcomputer used in the PWM controller of the present invention.
Fig. 10 is a schematic structural diagram of an installation embodiment of the harmonic source cabinet, the harmonic control cabinet and the measured sample according to the present invention.
Fig. 11 is a d-axis current closed-loop feedback control block diagram according to an embodiment of the present invention.
FIG. 12 is a block diagram of a d-axis current closed-loop feedback control after feedforward decoupling of FIG. 11 using a feedforward decoupling algorithm.
Fig. 13 is a block diagram of the d-axis current closed-loop feedback control simplified from fig. 12.
Fig. 14 is a decoupled d-axis current inner loop control block diagram according to the present invention.
Fig. 15 is a d-axis current inner loop control block diagram simplified from fig. 14.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
A low-voltage power quality detection system is disclosed, as shown in FIGS. 1-10, and comprises a power grid analog source 3 for simulating normal abnormal characteristics of a power supply grid 4 and checking adaptability of a sample to be detected to the power supply grid 4, a three-phase harmonic source 5 for outputting harmonic voltage, a reactive analog source 32 for providing a reactive compensation signal, a monitoring system for monitoring the system, a central controller 15 for controlling the system, and an upper computer 13 connected with the central controller 15, wherein the power grid analog source 3 is connected with the power supply grid 4, the sample 1 to be detected is connected with the power grid analog source 3 through a first transformer 2, the three-phase harmonic source 5, the reactive simulation sources 32 are connected with the tested sample 1 in parallel through a third transformer 37, and the power grid simulation source 3, the three-phase harmonic source 5, the reactive simulation sources 32, the first transformer 2, the tested sample 1 and the upper computer 13 are respectively connected with the monitoring system through the central controller 15.
In this embodiment, the power grid analog source is connected to a current detection module 35 for sampling current of the power grid analog source 3 and a voltage detection module 36 for sampling voltage of the power grid analog source 3, and the current detection module 35 and the voltage detection module 36 are respectively connected to the central controller 15 through the power factor compensation circuit 34.
In this embodiment, the power factor compensation circuit 34 includes a regulated power supply 344, a power factor compensation main circuit 341, a PWM pulse modulation and driving control circuit 343, and a phase current and voltage detection and comparison circuit 342, the regulated power supply 344 supplies power to the circuit, the power factor compensation main circuit 341 includes a first filter inductor 34109, a second filter inductor 34101, a first filter capacitor 34110, a second filter capacitor 34111, a third filter capacitor 34112, a charging and discharging capacitor 34107, an absorbing capacitor 34113, a coupling capacitor 34114, a second transformer 34106, a current detection resistor 34102, a first voltage detection resistor 03, a second voltage detection resistor 34104, a first power switch element 34108, and a second power switch element 34105, one end of the first filter inductor 34109 is connected to the ac input terminal L, and the other end of the first filter inductor 34109 is connected to the charging and discharging capacitor 34107, the first voltage detection resistor 34103, the first voltage detection resistor 34108, and the second power switch element 34105, One end of the current detection resistor 34102 is connected, the other end of the charge-discharge capacitor 34107 is connected to one end of a primary winding N1 of the second transformer 34106, the other end of a primary winding N1 of the second transformer 34106 is connected to the first power switching element 34108 and the second power switching element 34105 which are connected in parallel, a cathode of the first power switching element 34108 and an anode of the second power switching element 34105 are connected to a common end N of alternating current, and cathodes and driving electrodes of the first power switching element 34108 and the second power switching element 34105 are connected to the first driving circuit 3434 and the isolation driving circuit 3432 of the PWM pulse modulation and driving control circuit 343, respectively; one end of the first filter capacitor 34110 is connected to an input terminal L of the alternating current, and the other end of the first filter capacitor 34110 is connected to a common terminal N of the alternating current; one end of the second smoothing capacitor 34111 is connected to the first smoothing inductor 34109, and the other end of the second smoothing capacitor 34111 is connected to the common terminal N of the alternating current; the other end of the first voltage detection resistor 34103 is connected to one end of the voltage detection circuit 3423 of the phase current voltage detection and comparison circuit 342 and one end of the second voltage detection resistor 34104, respectively, and the other end of the second voltage detection resistor 34104 is connected to the common terminal N of the alternating current; the other end of the current detection resistor 34102 is connected to an output end LM of the alternating current through a second filter inductor 34101; the absorption capacitor 34113 is connected in parallel with the secondary winding N2 of the second transformer 34106, one end of the absorption capacitor 34113 is connected to the output terminal LM of the alternating current, the other end of the absorption capacitor 34113 is connected to one end of the coupling capacitor 34114, and the other end of the coupling capacitor 34114 is connected to the common terminal N of the alternating current; one end of the third filter capacitor 34112 and one end of the sample 1 are respectively connected to the output end LM of the alternating current, and the other end of the third filter capacitor 34112 and the other end of the sample 1 are respectively connected to the common end N of the alternating current. When the power factor compensation circuit works, alternating current AC is input at an input end L and a common end N of the power factor compensation main circuit, the alternating current AC is supplied to a circuit consisting of a charging and discharging capacitor, a primary winding N1 of a second transformer, a first power switching element and a second power switching element through a first filter capacitor, a first filter inductor and a second filter capacitor, and then is supplied to a sample to be detected after being filtered by a second filter inductor and a third filter capacitor through a current detection resistor;
in this embodiment, the voltage detection circuit 3423 of the phase current and voltage detection and comparison circuit detects the terminal voltage of the sample to be detected after voltage division by the first voltage detection resistor and the second voltage detection resistor in the power factor compensation main circuit; the current detection circuit 3421 detects the current flowing through the detected sample through the current detection resistor, processes the detected voltage and current waveforms, transmits the processed voltage and current waveforms to the current and voltage comparison circuit 3422 for comparison, controls the PWM pulse modulation circuit 3433 in the voltage control PWM pulse modulation and drive control circuit to control the first drive circuit 3434 and the isolation drive circuit 3432, and respectively controls the switching of the first power switch element 34108 and the second power switch element 34105; the voltage waveform detected by the voltage detection circuit 3423 is processed by the phase detection circuit 3424 and then transmitted to the phase and automatic power factor control circuit 3431 in the PWM pulse modulation and drive control circuit, the switching sequence of the first power switch element 34108 and the second power switch element 34105 is controlled by the phase and automatic power factor control circuit 3431 through the PWM pulse modulation circuit 3433, the first drive circuit 3434 and the isolation drive circuit 3432, the charge and discharge capacitor is charged in a pulse manner by the primary winding N1 of the second transformer in a period of 0-pi/2, and the charge and discharge capacitor is discharged in a pulse manner in a period of 3 pi/2-2 pi; carrying out pulse type discharge on the charge and discharge capacitor in a pi/2-pi period, and carrying out pulse type charge on the charge and discharge capacitor in a pi-3/2 pi period; when the power factor is lower than 1, the current and voltage comparison circuit in the phase current and voltage detection and comparison circuit outputs a constant voltage to control a PWM pulse modulation circuit in the PWM pulse modulation and driving control circuit, the first driving circuit and the isolation driving circuit respectively control the on-off time of the first power switching element and the second power switching element, and further control the on-off time of a primary winding N1 of the second transformer and the charging and discharging capacitor; when the alternating current is switched on and off in a pulse mode within the periods of 0-pi/2 and pi-3/2 pi, the first power switch element and the second power switch element adjust the charging quantity of the charge and discharge capacitor by adjusting the PWM pulse width, namely the on-off time; when the pulse is switched on and off in the periods of the alternating current pi/2-pi and 3/2 pi-2 pi, the first power switch element and the second power switch element adjust the discharge capacity of the charge-discharge capacitor by adjusting the PWM switching-on and switching-off time; the adjustment of the charge and discharge amount of the compensation charge and discharge capacitor is equivalent to the adjustment of the capacitance value of the compensation charge and discharge capacitor, so that dynamic compensation is realized; when the first power switch element and the second power switch element are respectively conducted, electric energy is stored in the first filter inductor when current passes through the first filter inductor, the charge-discharge capacitor and the primary winding N1 of the second transformer, and at the moment of switching off, the electric energy stored in the first filter inductor is released after being filtered by the second filter inductor and the third filter capacitor, so that power factor correction is carried out on a tested sample; on the other hand, the electric energy stored in the second transformer is discharged through the secondary winding N2, the absorption capacitor, and the coupling capacitor, and the power factor of the sample to be measured is corrected again.
In this embodiment, the three-phase harmonic source 5 includes a detection module 53, a harmonic generator 52 for outputting a harmonic voltage, and a PWM controller 51 for controlling a voltage frequency and an amplitude of the harmonic voltage output by the harmonic generator 52, the harmonic generator 52 is connected to the PWM controller 51, and the PWM controller 51 is connected to the upper computer 13; the harmonic generator 52 includes a first communication module 524, a relay output module 522, an analog output module 523, and a three-phase harmonic generation module 521, an input end of the detection module 53 is connected to the power supply grid 4, an output end of the detection module 53 is connected to the upper computer 13, the upper computer 13 is connected to an input end of the relay output module 522 and an input end of the analog output module 523 through the first communication module 524, an output end of the relay output module 522 and an output end of the analog output module 523 are connected to the three-phase harmonic generation module 521, and the three-phase harmonic generation module 521 is connected to the power supply grid 4.
In this embodiment, the three-phase harmonic generation module 521 includes an a-phase harmonic generation module 5211, a B-phase harmonic generation module 5212, and a C-phase harmonic generation module 5213, which have the same structure, and each of the a-phase harmonic generation module, the B-phase harmonic generation module, and the C-phase harmonic generation module is provided with a three-phase harmonic generation circuit 5210, the three-phase harmonic generation circuit includes a state monitor 52102, an ac contactor 52103, a relay 52104, a monotonic harmonic elimination circuit 52105, a high-pass harmonic elimination circuit 52107, and an anti-parallel thyristor 52106, an input end of the state monitor is connected to a power supply grid through a circuit breaker 52101, an output end of the state monitor is connected to one end of a relay contact through the ac contactor, the other end of the relay contact is connected to one end of the monotonic harmonic elimination circuit or the high-pass harmonic elimination circuit, the other end of the monotonic harmonic elimination circuit or the high-pass harmonic elimination circuit, the trigger signal input end of the anti-parallel thyristor is connected with the analog quantity output module, the coil of the relay is connected with the relay output module, and the communication port of the state monitor is connected with the first communication module. The state monitor is mainly used for realizing the state monitoring, the interlocking function and the detection of zero-crossing signals of all branches, and ensuring the correct attraction and inrush-free switching of the relay and the alternating current contactor.
In this embodiment, the monotonic resonance elimination circuit 52105 includes a first resistor 521053, a second reactor 521052, and a first capacitor 521051 connected in series.
In this embodiment, the high-pass harmonic elimination circuit 52107 includes a second resistor 521073, a third reactor 521071, a second capacitor 521072, and a third capacitor 521074, where the third capacitor is connected in series with the second resistor and then connected in parallel with the third reactor to form a parallel branch, and the parallel branch is connected in series with the second capacitor.
In this embodiment, the three-phase harmonic generation module 521 is provided with a front filter 16, a harmonic power module 17, and a rear filter 18, which are connected in sequence, the harmonic power module 17 includes a PWM rectifier 171 for establishing a stable dc voltage, a dc-side energy storage capacitor, and a PWM inverter 173 for generating a given voltage signal, the PWM rectifier 171, the dc-side energy storage capacitor 172, and the PWM inverter 173 are connected in sequence, an output end of the front filter 16 is connected to an input end of the PWM rectifier 171, an output end of the PWM inverter 173 is connected to the rear filter 18, and an output end of the PWM controller 51 is connected to the PWM rectifier 171 and the PWM inverter 173, respectively. Setting and displaying a three-phase current waveform interface, a state monitoring display interface and a harmonic generation frequency setting interface by an upper computer; the three-phase harmonic generation module formed by combining the front filter, the harmonic power module and the rear filter is adopted, and the PWM controller is used for controlling the three-phase harmonic generation module to simultaneously output harmonic voltages with multiple frequencies for superposition, so that the independent control of PWM rectification and inversion is achieved, the accuracy and reliability of control logic are ensured, and the accurate control of harmonic times and amplitude is realized.
In this embodiment, the front filter and the rear filter both adopt an RLC filtering mode, where the front filter and the rear filter both include a filter inductor, a filter resistor, and a filter capacitor that are connected to each other, the filter inductor is connected in series to the PWM rectifier, and the filter resistor and the filter capacitor are connected in series and then connected in parallel to the PWM rectifier.
In this embodiment, the PWM controller 51 simulates normal and abnormal characteristics of three-phase balance or unbalance of the power supply grid by using a three-phase decoupling algorithm, which includes the following specific contents:
the input current of the PWM controller 51 is provided by the following equation (a):
the formula (A) shows that the d-axis current and the q-axis current are mutually coupled, and the formula (A) is subjected to Laplace transform and is arranged to obtain the following formula (B):
with i1dAs controlled object, U1dAs the output of the PWM controller 51, the d-axis current closed-loop feedback control block shown in FIG. 11 can be obtained from the formula (B), and the current closed-loop controller output U can be derived from the d-axis current closed-loop feedback control block1dThe calculation formula (C) is:
wherein, the d-axis current and the q-axis current have symmetry, and the d-axis current and the q-axis current are subjected toControl variable U1d、U1qIs also influenced by the network side voltage U2d、U2qThe d-axis current and the q-axis current are mutually coupled to cause certain difficulty for the design of the PWM controller 51, and the influence of the difficulty on the system is effectively reduced by carrying out Laplace transformation on the formula (A); as can be seen from fig. 11, the d-axis current is not only related to the current setting, but also affected by the interference of the q-axis current and the d-axis component of the power supply grid voltage, so that the influence of the interference of the q-axis current and the d-axis component of the power supply grid voltage is eliminated by using the feedforward decoupling algorithm, the d-axis current inner loop closed-loop control block diagram using the feedforward decoupling algorithm is shown in fig. 12, and the output U of the closed-loop controller calculated by the feedforward decoupling algorithm is derived from the d-axis current inner loop closed-loop control block diagram1dThe calculation formula (D) is:
wherein, fig. 12 is simplified to obtain fig. 13, and it can be seen from fig. 13 that after disturbance of q-axis coupling current and power supply grid voltage is eliminated by adopting a feedforward decoupling algorithm, the current inner loop controlled object can be simplified into a simple first-order inertia link; meanwhile, the disturbance voltage of the power grid is introduced to be used as feedforward compensation, so that the anti-interference capability of the system is greatly improved.
Specifically, a current controller c(s) is selected as the PI controller, and the transfer function of c(s) is shown as a function (E):
wherein,considering the delay of current inner loop signal sampling and the small inertia characteristic of PWM control, the decoupled d-axis current inner loop control block diagram is shown in FIG. 14, TSFor the current inner loop current sampling period, KPWMBridge PWM equivalent gain; will be small time constantTSCombining to obtain a simplified decoupled d-axis current inner loop control block diagram as shown in fig. 15; when considering that the current inner loop needs to obtain a faster current following performance, it can be seen from the simplified decoupled d-axis current inner loop control block diagram shown in fig. 15 that only the zero of the designed PI regulator needs to cancel the pole of the current control object transfer function, that is:the corrected current inner loop open loop transfer function is shown as function (F):
when the system damping ratio ζ is taken to be 0.707, the calculation formula (G) can be obtained:
solving the formula (G) to obtain a calculation formula (H) of the current inner loop PI regulation control parameter:
the decoupled current inner loop closed loop transfer function is found from fig. 15 as function (I):
when the switching frequency is sufficiently high, i.e. TSSufficiently small due to S2The term coefficients are much smaller than the S term coefficients, so S can be ignored2Term, then the function (I) is simplified to function (J):
substituting the calculation formula (H) into the function (J) yields the simplified equivalent transfer function of the current inner loop as shown by the function (K):
the function (K) indicates: the current inner ring is approximately equivalent to an inertia link, and the inertia time constant of the inertia link is 3TS(ii) a Obviously, when the switching frequency is high enough, the current inner loop has a faster dynamic response; when the closed loop gain of the closed loop control system is reduced to-3 dB or its phase shift is-45 deg., this point can be defined as the closed loop system bandwidth fb(ii) a Because the current inner ring can be equivalent to a first-order inertia link, the frequency bandwidth f of the current inner ringbiIs shown in formula (L):
wherein f isSModulating the frequency for a current inner loop PWM switch; it can be known from formula (L) that the utility model relates to a PWM controller not only satisfies the rapidity requirement, also has stronger inhibition ability to high frequency interference such as switching frequency noise simultaneously.
In this embodiment, the PWM controller 51 is a single chip microcomputer 510, the single chip microcomputer 510 is provided with a dual port parallel RAM19, the dual port parallel RAM19 is provided with a data input port, a data output port, an address input port, and an address scanning port, and the data input port and the address input port of the dual port parallel RAM19 are connected to the single chip microcomputer 510; the single chip microcomputer 510 is connected with a first 8-bit parallel port analog-to-digital converter 24 and a second 8-bit parallel port analog-to-digital converter 26 which are used for regulating the amplitude, a data port of the first 8-bit parallel port analog-to-digital converter 24 and a data port of the second 8-bit parallel port analog-to-digital converter 26 are both connected with the single chip microcomputer 510, and a REF port of the first 8-bit parallel port analog-to-digital converter 24 and a REF port of the second 8-bit parallel port analog-to-digital converter 26 are connected with the output of the reference module 25.
In this embodiment, the single chip microcomputer 510 is further connected to a third 8-bit parallel port analog-to-digital converter 20 and a fourth 8-bit parallel port analog-to-digital converter 22 for controlling output waveforms, and the third 8-bit parallel port analog-to-digital converter 20 and the fourth 8-bit parallel port analog-to-digital converter 22 are both connected to the single chip microcomputer 510 through a data output port of the dual-port parallel port RAM 19.
In this embodiment, the output ports of the first 8-bit parallel port analog-to-digital converter 24 and the second 8-bit parallel port analog-to-digital converter 26 are respectively connected to the first operational amplifier array 23, the output port of the first operational amplifier array 23 is respectively connected to the REF ports of the third 8-bit parallel port analog-to-digital converter 20 and the fourth 8-bit parallel port analog-to-digital converter 22, the output ports of the third 8-bit parallel port analog-to-digital converter 20 and the fourth 8-bit parallel port analog-to-digital converter 22 are respectively connected to the second operational amplifier array 21, and the output port of the second operational amplifier array 21 is connected to the harmonic generator 52.
In this embodiment, the single chip microcomputer writes waveform data into the dual-port parallel RAM through the data input port and the address input port to establish a waveform table, and phase shifting can be achieved by writing different addresses. The single chip microcomputer transmits the high 8 bits and the low 8 bits of the amplitude signal to a first 8-bit parallel port analog-to-digital converter and a second 8-bit parallel port analog-to-digital converter respectively, the first 8-bit parallel port analog-to-digital converter and the second 8-bit parallel port analog-to-digital converter calculate output voltage through a reference module and transmit the output voltage to a first operational amplifier array, the first operational amplifier array transmits an output value to REF ports of a third 8-bit parallel port analog-to-digital converter and a fourth 8-bit parallel port analog-to-digital converter through proportional accumulation, and therefore the amplitude of an output waveform is regulated.
In this embodiment, the single chip writes the output waveform data into the dual-port parallel port RAM, writes the data at each time point into the third 8-bit parallel port analog-to-digital converter and the fourth 8-bit parallel port analog-to-digital converter, and calculates the output voltage through the reference voltage of the REF port of the third 8-bit parallel port analog-to-digital converter and the fourth 8-bit parallel port analog-to-digital converter, and transmits the output voltage to the second operational amplifier array, thereby outputting the required waveform phase.
In this embodiment, the detection module 6 includes a current transformer 61 and an analog-to-digital converter 62, an input end of the current transformer 61 is connected to the power supply grid 4, an output end of the current transformer 61 is connected to an input end of the analog-to-digital converter 62, and an output end of the analog-to-digital converter 62 is connected to the upper computer 13.
In this embodiment, the reactive power analog source 32 is provided with a reactive power generator 6, the reactive power generator 6 includes a first reactor 61 for storing energy and filtering high-frequency switch ripple current, a PWM converter 62 for providing a reactive power compensation signal in a three-phase fully controlled bridge topology form, and a second driving circuit 64, the first reactor 61 is connected to the power supply grid 4 through a third transformer 37, an ac side of the PWM converter 62 is connected to the first reactor 61, a dc side of the PWM converter 62 is connected to an energy storage capacitor 63, and the PWM converter 62 is connected to the central controller 15 through the second driving circuit 64; the three-phase harmonic source and the reactive simulation source are connected in parallel with the tested sample through the third transformer, the third transformer performs voltage transformation on harmonic voltage output by the harmonic generator and transmits electric energy, and the adaptability of the three-phase harmonic source in the process of checking the compensation capacity of the tested sample on the electric energy quality is improved; the PWM converter is composed of an insulated gate bipolar transistor, the insulated gate bipolar transistor is driven to generate a compensation current waveform through a voltage space vector modulation technology, and an energy storage capacitor stores direct current energy generated by the insulated gate bipolar transistor; the second driving circuit receives a control signal sent by the central controller, drives a semiconductor power device of the PWM converter and also has a protection function on the semiconductor power device; the reactive simulation source can compensate reactive power, adjust unbalanced three phases and suppress harmonic waves, avoids the problem of mutual interference, can flexibly configure reactive power on line, effectively realizes reasonable compensation of the reactive power, and provides safety guarantee for system equipment installed in extremely limited space.
In this embodiment, the harmonic generator 52 is disposed in the harmonic source cabinet 30, the single-chip microcomputer 510 is disposed in the harmonic control cabinet 31, the first transformer 2 and the third transformer 37 are disposed in each transformer cabinet 31, the grid simulation source 3, the harmonic source cabinet 30, the harmonic control cabinet 31, the reactive simulation source 32 and the transformer cabinets 31 are disposed beside the sample 1 to be tested, the sample 1 to be tested is disposed on the test rack 27, the test rack 27 is disposed on a wall surface, the test rack 27 is disposed on a wiring rack 28, the wiring rack 28 is supported below a ceiling by a support rack 29, the support rack 29 is fixedly disposed on the wall surface or the ceiling, the wiring rack 28 is disposed with a wiring slot 280, a cable is embedded in the wiring slot 280, and the grid simulation source 3, the harmonic source cabinet 30, the harmonic control cabinet 31, the reactive simulation source 32, the transformer 2 cabinet and the sample 1 to be tested are all connected to the power supply grid 4 through a cable. The mounting structure formed by combining the support frame, the wiring frame and the test frame provides higher stability, firmness and balance capability for mounting and wiring of system equipment, enables the system to be designed compactly and have higher safety, and fully utilizes limited test space.
In this embodiment, the monitoring system includes an electric energy quality analyzer 14 for detecting harmonics of the three-phase harmonic source 5 and transmitting the detected harmonic values to the central controller 15, a temperature sensor 8 for detecting temperature signals of the system equipment, a smoke sensor 9 for detecting smoke signals of the system equipment, a time monitoring module 10 for monitoring the operating state of the system, and an alarm module 12 for alarming the system, the three-phase harmonic source 5 and the reactive simulation source 32 are connected in parallel with the sample 1 to be measured through a transformer 2, the grid simulation source 3 is connected with the power supply grid 4, the grid simulation source 3 is connected with the sample 1 to be measured through a transformer 2, the alarm module 12 is connected with the upper computer 13, the grid simulation source 3, the three-phase harmonic source 5, the reactive simulation source 32, the transformer 2, the sample 1 to be measured, the electric energy quality analyzer 14, The temperature sensor 8, the smoke sensor 9, the time monitoring module 10 and the alarm module 12 are all connected with a central controller 15; the alarm module 12 includes a current-voltage alarm module 121 for sending out alarm information to alarm when the current value and/or the voltage value received by the central controller 15 exceeds a threshold value, a time alarm module 122 for sending out alarm information to alarm when the time value received by the central controller 15 exceeds the threshold value, a temperature alarm module 123 for sending out alarm information to alarm when the temperature value received by the central controller 15 exceeds the threshold value, a smoke alarm module 124 for sending out alarm information to alarm when the smoke concentration received by the central controller 15 exceeds the threshold value, and a harmonic alarm module 125 for sending out alarm information to alarm when the harmonic value received by the central controller 15 exceeds the threshold value, the current and voltage alarm module 121, the time alarm module 122, the temperature alarm module 123, the smoke alarm module 124 and the harmonic alarm module 125 are all connected with the central controller 15.
In this embodiment, the monitoring system further includes a second communication module 11, the second communication module 11 is connected to the central controller 15 and the alarm module, and the second communication module 11 transmits the alarm information to the upper computer 13.
In this embodiment, the monitoring system further includes a data storage module 7 connected to the central controller 15, and the data storage module 7 stores the alarm information.
In this embodiment, the data storage module 7 includes a database server 71 and a disk array 72 that are connected to each other, the database server 71 is connected to the central controller 15, the central controller 15 stores the alarm information in the disk array 72 through the database server 71, and the upper computer 13 reads the alarm information from the disk array 72. The technical scheme of the monitoring system is combined with a data storage module formed by combining the database server and the disk array, so that the reliability of the power quality detection system is improved, the integrity and the accuracy of power quality data are improved, different monitoring functions can be set according to monitoring requirements, an evaluation system is established by utilizing the data stored in the database server, the reliability of the low-voltage power quality detection system is reversely deduced according to the quality of the data, the remote reliability evaluation of the low-voltage power quality detection system is realized, the reliability of the system can also be diagnosed and analyzed, and the system is correspondingly overhauled and maintained according to the historical change trend of the reliability evaluation.
In this embodiment, the reactive power analog source 32 is provided with an RS485 interface, and the reactive power generator 6 is connected with the central controller 15 through the RS485 interface.
In this embodiment, the first transformer and the third transformer are respectively connected to the central controller 15 through RS485 interfaces.
In short, the above description is only a preferred embodiment of the present invention, and all the equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the scope of the present invention.
Claims (9)
1. A low-voltage power quality detection system is characterized in that: the device comprises a power grid simulation source (3) for simulating normal and abnormal characteristics of a power supply grid (4) and checking adaptability of a tested sample to the power supply grid (4), a three-phase harmonic source (5) for outputting harmonic voltage, a reactive simulation source (32) for providing reactive compensation signals, a monitoring system for monitoring the system, a central controller (15) for controlling the system, and an upper computer (13) connected with the central controller (15), wherein the power grid simulation source is connected with the power supply grid (4), the tested sample (1) is connected with the power grid simulation source (3) through a first transformer (2), the three-phase harmonic source (5) and the reactive simulation source (32) are connected with the tested sample in parallel through a third transformer, and the power grid simulation source (3), the three-phase harmonic source (5), the reactive simulation source (32), the first transformer (2), The tested sample (1) and the upper computer (13) are respectively connected with the monitoring system through a central controller (15); the power grid analog source (3) is connected with a current detection module (35) for sampling current of the power grid analog source (3) and a voltage detection module (36) for sampling voltage of the power grid analog source (3), and the current detection module (35) and the voltage detection module (36) are respectively connected to the central controller (15) through a power factor compensation circuit (34).
2. A low voltage power quality detection system according to claim 1, wherein: the power factor compensation circuit (34) comprises a stabilized voltage power supply (344), a power factor compensation main circuit (341), a PWM pulse modulation and drive control circuit (343), and a phase current voltage detection and comparison circuit (342) which are connected with each other, wherein the stabilized voltage power supply (344) supplies power to the circuit, the power factor compensation main circuit (341) comprises a first filter inductor (34109), a second filter inductor (34101), a first filter capacitor (34110), a second filter capacitor (34111), a third filter capacitor (34112), a charging and discharging capacitor (34107), an absorption capacitor (34113), a coupling capacitor (34114), a second transformer (34106), a current detection resistor (34102), a first voltage detection resistor (34103), a second voltage detection resistor (34104), a first power switch element (34108), and a second power switch element (34105), one end of the first filter inductor (34109) is connected with an input end L of alternating current, the other end of the first filter inductor (34109) is connected with one end of a charging and discharging capacitor (34107), a first voltage detection resistor (34103) and a current detection resistor (34102), the other end of the charging and discharging capacitor (34107) is connected with one end of a primary winding N1 of a second transformer (34106), the other end of a primary winding N1 of the second transformer (34106) is connected with a first power switch element (34108) and a second power switch element (34105) which are connected in parallel, a cathode of the first power switch element (34108) and an anode of the second power switch element (34105) are connected to a common end N of alternating current, and cathodes and driving electrodes of the first power switch element (34108) and the second power switch element (34105) are connected to a first driving circuit (3434) and an isolated driving circuit (3432) of the PWM pulse modulation and driving control circuit (343), respectively; one end of the first filter capacitor (34110) is connected to an input terminal L of the alternating current, and the other end of the first filter capacitor (34110) is connected to a common terminal N of the alternating current; one end of the second filter capacitor (34111) is connected with the first filter inductor (34109), and the other end of the second filter capacitor (34111) is connected to the common end N of the alternating current; the other end of the first voltage detection resistor (34103) is respectively connected with one end of a voltage detection circuit (3423) of the phase current and voltage detection and comparison circuit (342) and one end of a second voltage detection resistor (34104), and the other end of the second voltage detection resistor (34104) is connected to a common end N of alternating current; the other end of the current detection resistor (34102) is connected to an output end LM of the alternating current through a second filter inductor (34101); a snubber capacitor (34113) is connected in parallel with the secondary winding N2 of the second transformer (34106), one end of the snubber capacitor (34113) is connected to the output terminal LM of the alternating current, the other end of the snubber capacitor (34113) is connected to one end of the coupling capacitor (34114), and the other end of the coupling capacitor (34114) is connected to the common terminal N of the alternating current; one end of the third filter capacitor (34112) and one end of the sample (1) to be tested are respectively connected with the output end LM of the alternating current, and the other end of the third filter capacitor (34112) and the other end of the sample (1) to be tested are respectively connected with the common end N of the alternating current.
3. A low voltage power quality detection system according to claim 1 or 2, wherein: the three-phase harmonic source (5) comprises a detection module (53), a harmonic generator (52) for outputting harmonic voltage, and a PWM controller (51) for controlling the voltage frequency and amplitude of the harmonic voltage output by the harmonic generator (52), wherein the harmonic generator (52) is connected with the PWM controller (51), and the PWM controller (51) is connected with the upper computer (13); harmonic generator (52) include first communication module (524), relay output module (522), analog output module (523), three-phase harmonic generation module (521), the input and power supply electric wire netting (4) of detection module (53) are connected, the output and the host computer (13) of detection module (53) are connected, host computer (13) are connected with the input of relay output module (522) and the input of analog output module (523) respectively through first communication module (524), the output of relay output module (522) and the output of analog output module (523) are connected with three-phase harmonic generation module (521) respectively, three-phase harmonic generation module (521) are connected with power supply electric wire netting (4).
4. A low voltage power quality detection system according to claim 3, wherein: the three-phase harmonic generation module (521) comprises an A-phase harmonic generation module (5211), a B-phase harmonic generation module (5212) and a C-phase harmonic generation module (5213) which are completely identical in structure, the A-phase harmonic generation module (5211), the B-phase harmonic generation module (5212) and the C-phase harmonic generation module (5213) are respectively provided with a three-phase harmonic generation circuit (5210), the three-phase harmonic generation circuit (5210) comprises a state monitor (52102), an alternating current contactor (52103), a relay (52104), a monotonic harmonic elimination circuit (52105), a high-pass harmonic elimination circuit (52107) and an anti-parallel thyristor (52106), the input end of the state monitor (52102) is connected with a power supply grid through a breaker, the output end of the state monitor (52102) is connected with one end of a contact of the relay (52104) through the alternating current contactor (52103), the other end of the contact of the relay (52104) is connected with one end of the monotonic harmonic elimination circuit (52105), the other end of the monotone harmonic elimination circuit (52105) or the high-pass harmonic elimination circuit (52107) is connected with one end of an anti-parallel thyristor (52106), the other ends of the anti-parallel thyristors (52106) of all branches are connected together, the trigger signal input end of the anti-parallel thyristor (52106) is connected with the analog quantity output module (523), the coil of the relay (52104) is connected with the relay output module (522), and the communication port of the state monitor (52102) is connected with the first communication module (524).
5. A low voltage power quality detection system according to claim 4, wherein: three-phase harmonic generation module (521) is equipped with preceding filter (16), harmonic power module (17), back filter (18) that connect gradually, harmonic power module (17) are including PWM rectifier (171) that are used for establishing stable direct current voltage, direct current side energy storage capacitor (172), PWM inverter (173) that are used for generating given voltage signal, PWM rectifier (171), direct current side energy storage capacitor (172), PWM inverter (173) connect gradually, the output of preceding filter (16) is connected with the input of PWM rectifier (171), the output of PWM inverter (173) is connected with back filter (18), the output of PWM controller (51) is connected with PWM rectifier (171), PWM inverter (173) respectively.
6. A low voltage power quality detection system according to claim 4 or 5, wherein: the PWM controller (51) adopts a single chip microcomputer (510), the single chip microcomputer (510) is provided with a dual-port parallel port RAM (19), the dual-port parallel port RAM (19) is provided with a data input port, a data output port, an address input port and an address scanning port, and the data input port and the address input port of the dual-port parallel port RAM (19) are connected to the single chip microcomputer (510); the single chip microcomputer (510) is connected with a first 8-bit parallel port analog-to-digital converter (24) and a second 8-bit parallel port analog-to-digital converter (26) which are used for regulating the amplitude, a data port of the first 8-bit parallel port analog-to-digital converter (24) and a data port of the second 8-bit parallel port analog-to-digital converter (26) are both connected with the single chip microcomputer (510), and a REF port of the first 8-bit parallel port analog-to-digital converter (24) and a REF port of the second 8-bit parallel port analog-to-digital converter (26) are connected with the output of the reference module (25.
7. A low voltage power quality detection system according to claim 6, wherein: the single chip microcomputer (510) is further connected with a third 8-bit parallel port analog-to-digital converter (20) and a fourth 8-bit parallel port analog-to-digital converter (22) which are used for controlling output waveforms, and the third 8-bit parallel port analog-to-digital converter (20) and the fourth 8-bit parallel port analog-to-digital converter (22) are connected to the single chip microcomputer (510) through a data output port of the dual-port parallel port RAM (19).
8. A low voltage power quality detection system according to claim 7, wherein: the output ports of the first 8-bit parallel port analog-to-digital converter (24) and the second 8-bit parallel port analog-to-digital converter (26) are respectively connected with the first operational amplifier array (23), the output end of the first operational amplifier array (23) is respectively connected with the REF ports of the third 8-bit parallel port analog-to-digital converter (20) and the fourth 8-bit parallel port analog-to-digital converter (22), the output ends of the third 8-bit parallel port analog-to-digital converter (20) and the fourth 8-bit parallel port analog-to-digital converter (22) are respectively connected with the second operational amplifier array (21), and the output end of the second operational amplifier array (21) is connected with the harmonic generator (52).
9. A low voltage power quality detection system according to claim 1 or 2 or 4 or 5 or 7 or 8 wherein: reactive power analog source (32) are equipped with reactive power generator (6), reactive power generator (6) are including first reactor (61) that is used for energy storage and filtering high frequency switch ripple current, adopt three-phase full control bridge topology form to provide reactive compensation signal PWM converter (62), second drive circuit (64), first reactor (61) are connected with power supply network (4) through third transformer (37), the interchange side and first reactor (61) of PWM converter (62) are connected, the direct current side and the energy storage capacitor (63) of PWM converter (62) are connected, PWM converter (62) are connected to central controller (15) through second drive circuit (64).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109470967A (en) * | 2019-01-16 | 2019-03-15 | 中检质技检验检测科学研究院有限公司 | Low-voltage electric energy quality detecting system |
| CN111628511A (en) * | 2020-07-03 | 2020-09-04 | 上海艾临科智能科技有限公司 | Reactive compensation system and reactive compensation method |
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2019
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109470967A (en) * | 2019-01-16 | 2019-03-15 | 中检质技检验检测科学研究院有限公司 | Low-voltage electric energy quality detecting system |
| CN111628511A (en) * | 2020-07-03 | 2020-09-04 | 上海艾临科智能科技有限公司 | Reactive compensation system and reactive compensation method |
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