CN112653162B - Voltage sag compensation device and method - Google Patents
Voltage sag compensation device and method Download PDFInfo
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- CN112653162B CN112653162B CN202011499961.3A CN202011499961A CN112653162B CN 112653162 B CN112653162 B CN 112653162B CN 202011499961 A CN202011499961 A CN 202011499961A CN 112653162 B CN112653162 B CN 112653162B
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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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
Abstract
The invention relates to a voltage sag compensation device and a voltage sag compensation method. The voltage sag compensation device includes: the power grid comprises an energy storage unit for acquiring output voltage of a power grid and outputting direct current, an inversion unit for converting the input direct current into alternating current and outputting the alternating current, a boosting unit, a detection unit, a control unit, a first switch and a second switch; the detection unit detects output parameters of the power grid in real time and outputs the output parameters to the control unit, and when the control unit determines that voltage sag occurs according to the output parameters of the power grid, the first switch is controlled to be opened, the second switch is controlled to be closed, and the boosting unit supplies power to the load after coupling the power grid voltage input by the power grid through the second switch and the output voltage of the inversion unit. Through the voltage sag compensation device, the problem that the voltage sag compensation capacity is low when the voltage sag occurs can be solved.
Description
Technical Field
The invention relates to the technical field of power supply, in particular to a voltage sag compensation device and a voltage sag compensation method.
Background
With the wide application of modern sensitive power electronic equipment and the rapid development of novel power loads, the problem of dynamic power quality is increasingly focused, and voltage sag becomes a primary problem affecting the power quality, and serious voltage sag stops the operation of electric equipment or causes the quality of produced products to be reduced.
At present, the control and improvement measures of the voltage sag at the user side mainly comprise the installation of a voltage sag suppression or compensation device, and the products on the market mainly comprise uninterruptible power supplies, dynamic voltage regulators and the like. However, the device has the problems of low voltage detection speed and low compensation response speed at present, so that the voltage sag compensation capability is low, and the requirement of sensitive electronic equipment on the voltage sag compensation cannot be met.
Disclosure of Invention
Based on this, it is necessary to provide a voltage sag compensation device and method capable of rapidly performing voltage sag compensation.
A voltage sag compensation device, the voltage sag compensation device comprising:
the power grid comprises an energy storage unit for acquiring output voltage of a power grid and outputting direct current, an inversion unit for converting the input direct current into alternating current and outputting the alternating current, a boosting unit, a detection unit, a control unit, a first switch and a second switch;
one end of the energy storage unit, one end of the first switch, one end of the second switch and one end of the detection unit are connected with a power grid, the other end of the energy storage unit is connected with the input end of the inversion unit, the output end of the inversion unit is connected with the first input end of the boosting unit, the second input end of the boosting unit is connected with the other end of the second switch, and the other end of the first switch and the output end of the boosting unit are connected with a load; the other end of the detection unit and the control end of the inversion unit are connected with the control unit;
the detection unit detects output parameters of the power grid in real time and outputs the output parameters to the control unit, and when the control unit determines that voltage sag occurs according to the output parameters of the power grid, the first switch is controlled to be opened, the second switch is controlled to be closed, and the boost unit is used for supplying power to a load after coupling the power grid voltage input by the power grid through the second switch and the output voltage of the inversion unit.
In one embodiment, the control unit is further configured to determine a voltage sag compensation parameter when it is determined that a voltage sag occurs, and adjust the output voltage of the inverter unit according to the voltage sag compensation parameter.
In one embodiment, the energy storage unit is a voltage stabilizing capacitor or a super energy storage capacitor for storing and stabilizing the voltage input by the power grid.
In one embodiment, the energy storage unit is the voltage stabilizing capacitor, and the apparatus further includes:
a rectifier connected between the grid and the regulated capacitor; the rectifier, the voltage stabilizing capacitor and the inversion unit form a back-to-back converter.
In one embodiment, the control unit is further configured to control the first switch to be closed and the second switch to be opened when it is determined that no voltage dip occurs, and power a load by the grid voltage output by the grid through the first switch.
In one embodiment, the first switch and the second switch are high-efficiency ultra-thin switches.
In one embodiment, the power inverter further comprises a filtering unit, and the inversion unit is connected with the boosting unit through the filtering unit.
A voltage sag compensation method, comprising:
acquiring output parameters of the power grid detected by the detection unit;
according to the output parameters of the power grid, when the occurrence of voltage sag is determined, converting direct current output by the energy storage unit into alternating current for output, coupling output voltage with the voltage of the power grid, and supplying power to a load by using the coupled voltage.
In one embodiment, the method further comprises:
when determining that voltage sag occurs, determining a voltage sag compensation parameter, and regulating the output voltage by adopting sine pulse width modulation voltage regulation according to the voltage sag compensation parameter;
or according to the voltage sag compensation parameter, adopting in-bridge phase shifting voltage regulation to regulate the output voltage.
In one embodiment, the method comprises the steps of:
and the detection unit obtains the output parameters of the power grid by carrying out phase-locked tracking on the power grid voltage.
The voltage sag compensation device comprises: the power grid comprises an energy storage unit for acquiring output voltage of a power grid and outputting direct current, an inversion unit for converting the input direct current into alternating current and outputting the alternating current, a boosting unit, a detection unit, a control unit, a first switch and a second switch; one end of the energy storage unit, one end of the first switch, one end of the second switch and one end of the detection unit are connected with the power grid, the other end of the energy storage unit is connected with the input end of the inversion unit, the output end of the inversion unit is connected with the first input end of the boosting unit, the second input end of the boosting unit is connected with the other end of the second switch, and the other end of the first switch and the output end of the boosting unit are connected with a load; the other end of the detection unit and the control end of the inversion unit are connected with the control unit; the detection unit detects output parameters of the power grid in real time and outputs the output parameters to the control unit, and when the control unit determines that voltage sag occurs according to the output parameters of the power grid, the control unit controls the first switch to be opened and the second switch to be closed, and the boosting unit supplies power to the load after coupling the power grid voltage input by the power grid through the second switch and the output voltage of the inversion unit.
After the voltage sag occurs, the power grid voltage is controlled to be coupled with the output voltage of the inversion unit, and then the load is supplied with power, so that the efficiency of voltage sag compensation is improved.
Drawings
In order to more clearly illustrate the technical solutions of embodiments or conventional techniques of the present application, the drawings required for the descriptions of the embodiments or conventional techniques will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a block diagram of a voltage sag compensation device according to one embodiment;
FIG. 2 is a diagram of a medium rectification circuit of the voltage sag compensation device of FIG. 1;
FIG. 3 is a flow chart illustrating a voltage sag compensation method according to an embodiment.
Detailed Description
In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Examples of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that the terms "first," "second," and the like, as used herein, may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another element. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. Both the first resistor and the second resistor are resistors, but they are not the same resistor.
It is to be understood that in the following embodiments, "connected" is understood to mean "electrically connected", "communicatively connected", etc., if the connected circuits, modules, units, etc., have electrical or data transfer between them.
As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," and/or the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof. Also, the term "and/or" as used in this specification includes any and all combinations of the associated listed items.
As shown in fig. 1, the voltage sag compensation device of an embodiment includes an energy storage unit 100 that obtains an output voltage of a power grid and outputs a direct current, an inverter unit 200 that converts the input direct current into an alternating current and outputs the alternating current, a voltage boosting unit 300, a detection unit 400, a control unit 500, a first switch 600, and a second switch 700.
One end of the energy storage unit 100, the first switch 600, the second switch 700 and the detection unit 400 is connected with a power grid, the other end of the energy storage unit 100 is connected with the input end of the inversion unit 200, the output end of the inversion unit 200 is connected with the first input end of the boost unit 300, the second input end of the boost unit 300 is connected with the other end of the second switch 700, and the other end of the first switch 600 and the output end of the boost unit 300 are connected with a load; the other end of the detection unit 400 and the control end of the inversion unit are connected to the control unit 500.
The detection unit 400 detects output parameters of the power grid in real time and outputs the output parameters to the control unit 500, when the control unit 500 determines that voltage sag occurs according to the output parameters of the power grid, the first switch 600 is controlled to be opened, the second switch 700 is controlled to be closed, and the boost unit 300 is used for supplying power to the load after coupling the power grid voltage input by the power grid through the second switch 700 and the output voltage of the inversion unit 200.
The control unit 500 detects output parameters of the power grid in real time according to the detection unit 400, and determines whether a voltage sag occurs, where the output parameters of the power grid may include a voltage parameter, a current parameter, a frequency parameter, and the like output by the power grid.
When it is determined that no dip occurs in the voltage of the power grid according to the output parameter of the power grid, the power grid alone supplies power to the load, and at this time, the control unit 500 controls the first switch 600 to be closed and the second switch 700 to be opened, for example, the control unit may control the first switch 600 and the second switch 700 to be closed and opened by means of a wireless network.
When the voltage of the power grid has a dip, the control unit 500 controls the first switch 600 to be opened, the second switch 700 to be closed, and the inverter unit 200 to perform voltage compensation, wherein the control unit 500 can determine the voltage dip compensation parameter based on the output parameter of the power grid, so as to regulate and control the output voltage of the inverter unit 200, the boost unit 300 couples the power grid voltage with the output voltage of the inverter unit 200 and then supplies power to the load, and specifically, the power grid voltage and the output unit of the inverter unit 200 are input to the boost unit 300 and then are coupled by the boost unit 300 and then supply power to the load.
The energy storage unit 100 may be a voltage stabilizing capacitor or a super energy storage capacitor, where the super energy storage capacitor is a novel energy storage capacitor between a traditional capacitor and a rechargeable battery, and has the characteristic of rapid charging and discharging of the capacitor, and the energy storage characteristic of the battery.
The voltage stabilizing capacitor can also store the input voltage of the power grid, and meanwhile, the voltage stabilizing capacitor can be connected in parallel to two ends of the output side of the rectifier, and is used for filtering out residual alternating voltage and harmonic components after rectification of the rectifier and pulling the unidirectional wave pulse voltage output by the rectifier to an approximately smooth voltage value in a high-charge and low-discharge mode, so that the voltage stabilizing effect is achieved.
Therefore, when the energy storage unit 100 is a voltage-stabilizing capacitor, a rectifier is further included, and the rectifier is used for converting the ac output by the power grid into dc output. The rectifier may be a half-wave rectifier, a full-wave bridge rectifier, a voltage doubler rectifier, or any other rectifier capable of converting ac power into dc power.
In one embodiment, as shown in fig. 2, a full-wave bridge rectifier is selected as the rectifier, and the full-wave bridge rectifier is provided with a first input pole and a second input pole for connecting to the grid ac input power source Vin, and a first output pole and a second output pole for outputting the dc power Vout. The full bridge rectifier is used for converting alternating current into direct current. The full wave bridge rectifier includes 4 diodes: diode D1, diode D2, diode D3, and diode D4. The anode of the diode D1 is connected to the cathode of the diode D4, the anode of the diode D2 is connected to the cathode of the diode D3, the cathode of the diode D1 is connected to the cathode of the diode D2, and the anode of the diode D3 and the anode of the diode D4 are connected.
The common connection point of the diode D1 and the diode D4 is used as a first input pole of the input power source Vin, and the common connection point of the diode D2 and the diode D3 is used as a second input pole of the input power source Vin. The common connection point of the diode D1 and the diode D2 is used as a first input pole outputting the direct current Vout, and the common connection point of the diode D3 and the diode D4 is used as a second input pole outputting the direct current Vout.
At the positive half cycle of the ac input power Vin, the diode D1 and the diode D3 are turned on, the diode D2 and the diode D4 are turned off, and the current enters from the first input pole, flows through the diode D1 to the first output pole, flows through the diode D3 to the second input pole.
In the negative half cycle of the ac input power Vin, the diode D1 and the diode D3 are turned off, the diode D2 and the diode D4 are turned on, and the current enters from the second input pole, flows through the diode D2 to the first output pole, and flows through the diode D4 to the first input pole. Thus, half cycle signals are always output at the DC voltage output. In theory, vout=0.9 Vin.
The rectified voltage output by the rectifier may not be a complete direct current voltage, but is a unidirectional pulsating voltage composed of unidirectional half waves, the rectified voltage output by the rectifier not only has jump of intensity change, but also contains residual alternating voltage and harmonic wave change components, in order to remove the alternating voltage and the harmonic wave components, a voltage stabilizing capacitor with enough capacity can be connected in parallel at two sides of a first output pole and a second output pole of the rectifier, the grid voltage output by the rectifier is input to the voltage stabilizing capacitor, the unidirectional pulsating voltage can be regulated to be approximately smooth voltage value through high charge and low discharge, wherein the high charge and low discharge means that when the voltage input to the voltage stabilizing capacitor by the rectifier is larger than the voltage of the voltage stabilizing capacitor, the voltage stabilizing capacitor charges, when the voltage input to the voltage stabilizing capacitor by the rectifier is smaller than the voltage of the voltage stabilizing capacitor, the voltage stabilizing capacitor charges and discharges, and the unidirectional pulsating voltage output by the rectifier can be regulated to be approximately smooth voltage value through charge and discharge regulation. The rectifier output contains residual alternating voltage and harmonic variation components, and can be connected to the ground through the voltage stabilizing capacitor based on the function of the voltage stabilizing capacitor for blocking direct current and alternating current.
The inverter unit 200 may be an inverter, and the inverter may convert an input direct current into an alternating current, where the inverter unit 200 may be a single-phase inverter, a three-phase inverter, a half-bridge inverter, a full-bridge inverter, and other types of inverters, and in the embodiment of the present application, the inverter unit 200 adopts a cascade H-bridge type multi-level inverter, and the cascade H-bridge type multi-level inverter may maintain a higher equivalent switching frequency and a lower switching loss, and according to actual requirements, the inverter unit 200 may also adopt other types of inverters.
The step-up unit 300 may be a step-up transformer, wherein the transformer is a device for changing ac voltage by using electromagnetic induction principle, and has the main functions of voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc. The transformer comprises an iron core (or magnetic core) and a coil, wherein the coil is provided with two or more windings, the windings connected with an alternating current power supply are called primary coils (primary side coils and primary coils), and the other windings are called secondary coils (secondary side coils and secondary coils). The simplest iron core transformer is composed of an iron core made of soft magnetic material, and a primary coil L1 and a secondary coil L2 which are sleeved on the iron core and have different numbers of turns. In the embodiment of the application, the step-up transformer is adopted to supply power to the load after the power grid voltage input by the power grid through the second switch is coupled with the output voltage of the inversion unit.
The detection unit 400 may be a single chip microcomputer integrated on the same circuit chip and having data processing capability, an a/D conversion circuit and timing function, for example, a single chip microcomputer with a model number of ATMGA88PA-AU may be used to sample and record output parameters of a power grid, where the output parameters of the power grid may include output voltage parameters, current parameters and frequency parameters, and sampling and recording interval time is set. For example, the sampling record interval time is set to 67 microseconds to achieve the purpose of timely detecting the power grid parameters, and meanwhile, the control unit can also timely judge whether the power grid voltage has a dip or not after detecting the power grid parameters.
In one embodiment, the first switch 600 and the second switch 700 are SDR switches, when no voltage dip occurs, the control unit 500 controls the first switch 600 to be closed, the second switch 700 to be opened, the power grid voltage alone supplies power to the load, when the voltage dip occurs, the control unit 500 controls the first switch 600 to be closed, the second switch 700 to be opened, and the power grid voltage and the output voltage of the inverter unit 200 are coupled to supply power to the load.
After determining that the voltage sag occurs according to the output parameters of the power grid, the control unit 500 further determines a voltage sag compensation parameter based on the output parameters of the power grid, and adjusts the output voltage of the inverter unit according to the voltage sag compensation parameter.
The voltage sag refers to a phenomenon that the root mean square value of power frequency voltage at a certain point in a power grid suddenly decreases to 0.1-0.9p.u. (per unit value), and the power frequency voltage returns to normal after lasting for 10ms-1min, for example, if 220v is set to be 1p.u., 0.1 p.u. is 22v,0.9 p.u. is 198v, and if the power grid voltage lasts for 10ms-1min, the power grid voltage suddenly decreases to 22 v-198 v, the voltage sag appears. Optionally, the output parameters of the power grid further include a current parameter and a frequency parameter, and the control unit 500 may also determine whether the voltage has a dip through the current parameter and the frequency parameter.
When determining that a voltage sag occurs according to the voltage parameter, the current parameter or the frequency parameter, the control unit 500 may determine a voltage sag compensation parameter through an output parameter of the power grid, and adjust the output voltage of the inverter according to the voltage sag compensation parameter.
The voltage sag compensation parameter calculation method may be obtained by calculating an obtained power grid output parameter, for example, according to an obtained power grid output voltage calculation, wherein the power grid transmits a voltage to a load end based on a three-phase alternating current form, obtains a voltage of the three-phase load end, performs park transformation on the three-phase load voltages Ua, ub, uc to obtain a direct-axis voltage and quadrature-axis voltage Ud, uq under a two-phase rotation coordinate system, performs low-pass filtering on the direct-axis voltage and the quadrature-axis voltage Ud through a low-pass filter to obtain a low-frequency component of the direct-axis voltage and a low-frequency component of the quadrature-axis voltage, performs park inverse transformation on the low-frequency component of the direct-axis voltage and the low-frequency component of the quadrature-axis voltage to obtain three-phase intermediate voltages Ua ', ub ' and Uc ' under a three-phase static coordinate system, and then performs park transformation on the three-phase intermediate voltages Ua, ub ' and Uc ' respectively and the three-phase bus voltage to obtain the three-phase voltage sag compensation parameter. After the voltage sag compensation parameter is calculated, the output voltage of the inversion unit can be adjusted according to the voltage sag compensation parameter.
In one embodiment, the rectifier, the voltage stabilizing capacitor and the inverter unit form a back-to-back converter.
The back-to-back converter can output alternating current input by a power grid from one frequency to another, and the conversion process is completed through frequency change. The back-to-back converter comprises a step-up back-to-back converter and a step-down back-to-back converter, wherein the step-up back-to-back converter is used for converting alternating current input by a power grid from one frequency to a higher frequency, and the step-down back-to-back converter is used for converting alternating current input by the power grid from one frequency to a lower frequency. In one embodiment, the rectifier, the voltage stabilizing capacitor and the inversion unit form a back-to-back converter, and the back-to-back converter compensates voltage sag by injecting reactive power, can detect reactive power and harmonic waves at the load side, compensates voltage during voltage sag, and can perform reactive power compensation and harmonic suppression on the load during normal operation of the system.
In one embodiment, the power inverter further comprises a filtering unit, and the inversion unit is connected with the boosting unit through the filtering unit.
The filter unit can be a passive filter and an active filter, and the filter can filter the received alternating current output by the inversion singular number, so that the impurity interference signal is prevented from interfering the driving signal. Specifically, the filter includes a passive filter which may be composed of passive elements (resistor, capacitor, inductor), and its main forms are capacitive filtering, inductive filtering, and duplex filtering (including inverted-L, LC filtering, LC pi filtering, RC pi filtering, etc.). The active filter may also consist of active elements (bipolar, unipolar, integrated op-amp), the main form of which is active RC filtering. In one embodiment, an LC filter circuit is used to filter the ac voltage output by the inverter unit to filter out the interference components of the ac voltage, where the LC filter may be formed by appropriately combining a filter reactor, a capacitor and a resistor, and is connected in parallel with the harmonic source, so that the reactive compensation is also considered in addition to the filtering function.
In one embodiment, as shown in fig. 3, a voltage sag compensation method is provided, the method comprising the steps of:
s302, obtaining output parameters of the power grid detected by the detection unit.
When the control unit needs to determine whether the voltage sag exists or not, the output parameters of the power grid detected by the detection unit need to be acquired first, the detection unit can be a single chip microcomputer integrated on the same circuit chip and having data processing capability, an A/D conversion circuit and a timing function, for example, the single chip microcomputer with the model of ATMGA88PA-AU can be used for sampling and recording the output parameters of the power grid, wherein the output parameters of the power grid can comprise the output voltage parameters, current parameters and frequency parameters.
S304, according to the output parameters of the power grid, when the occurrence of voltage sag is determined, converting direct current output by the energy storage unit into alternating current for output, coupling output voltage with the voltage of the power grid, and supplying power to a load by using the coupled voltage.
The voltage sag refers to a change phenomenon that the root mean square value of power frequency voltage at a certain point in a power grid suddenly decreases to 0.1-0.9p.u., and returns to normal after lasting for 10ms-1min briefly. Wherein the control unit can determine whether voltage sag occurs according to the voltage parameter, the current parameter or the frequency parameter, and when the voltage sag occurs, the control unit converts direct current output by the energy storage unit into alternating current to output, couples the output voltage with the power grid voltage, supplies power to the load by adopting the coupled voltage,
in one embodiment, the method further comprises:
when the occurrence of voltage sag is determined, determining a voltage sag compensation parameter, and regulating the output voltage by adopting sine pulse width modulation voltage regulation or phase-shifting voltage regulation in a bridge according to the voltage sag compensation parameter.
The voltage sag compensation parameter is a parameter for regulating and controlling an output voltage, which is calculated by a control unit according to an output parameter of a power grid, wherein the calculation method of the voltage sag compensation parameter is obtained according to the obtained power grid output parameter, for example, the power grid transmits the voltage to a load end based on a three-phase alternating current form, the voltage of the three-phase load end is obtained, the three-phase load voltages Ua, ub and Uc are subjected to park transformation to obtain a direct-axis voltage and a quadrature-axis voltage Ud and Uq under a two-phase rotating coordinate system, the direct-axis voltage and the quadrature-axis voltage Ud and Uq are subjected to low-pass filtering through a low-pass filter to obtain a low-frequency component of the direct-axis voltage and a low-frequency component of the quadrature-axis voltage, park inverse transformation is performed on the low-frequency component of the direct-axis voltage and the low-frequency component of the quadrature-axis voltage to obtain three-phase intermediate voltages Ua ', ub ' and Uc ' under the three-phase stationary coordinate system, and then the three-phase intermediate voltages Ua, ub ' and Uc ' are respectively subjected to corresponding difference with the three-phase voltage to obtain the three-phase sag compensation parameter. After the voltage sag compensation parameter is calculated, the output voltage of the inversion unit can be adjusted according to the voltage sag compensation parameter.
After the voltage sag compensation parameter is calculated, the control unit may adjust the output voltage in a Pulse Width Modulation (PWM) manner, and the PWM circuit may be used to adjust the pulse width of the pulse signal, including but not limited to adjusting the period and duty cycle of the pulse signal, by a PWM controller integrated within a microcontroller or DSP (Digital Signal Processor, digital signal processing) chip, or by a discrete device. Specifically, the PWM circuit may include a switching device, one end of which may be used to receive an input electrical signal. The switching state of the switching device is adjusted along with the voltage of the input electric signal, so that the voltage at the other end of the switching device is changed, and the output of the pulse signal is realized. The on time and the off time of the switching device can be changed by adjusting the input electric signal, so that the pulse width can be adjusted.
In one embodiment, the output voltage of the inverter may be regulated by adopting a sine pulse width modulation voltage regulation method, where the sine pulse width modulation method refers to that a plurality of pulses in each sine period are subjected to natural or regular width modulation, so that the pulses are sequentially modulated to form a pulse sequence with phase angles and areas equivalent to sine function values and sine waves, and sinusoidal current output with equal amplitude and unequal width is formed. Wherein the ratio of the weekly fundamental wave (sinusoidal modulation wave) to the total number of pulses of the contained modulation output is the carrier ratio. When the control unit determines that voltage sag occurs, based on the determined voltage sag compensation parameter, the fundamental value of the fundamental wave of the output voltage of the inversion unit is controlled to be continuously adjusted along with the voltage of the externally applied control signal, the basic function of the inversion unit is to change direct current electric energy into alternating current electric energy with required frequency, but in the voltage compensation device, the voltage compensation device is required to have a frequency conversion function, and the voltage of the output end of the inversion unit is required to be continuously adjustable within a certain range when the voltage sag occurs.
In one embodiment, the output voltage of the inverter unit may be further adjusted by an in-bridge phase-shifting voltage-adjusting method: by changing the waveform of the output voltage, the fundamental wave square root value and the amplitude of each subharmonic of the output voltage are changed. The phase-shifting voltage-regulating mode in the bridge has the advantages of simple control, good voltage regulating linearity and larger harmonic content of output voltage.
In one embodiment, the method further comprises;
and the detection unit performs phase-locked tracking on the power grid voltage and detects the output parameters of the power grid in real time.
The detection unit may be a single chip microcomputer integrated on the same circuit chip and having data processing capability, an a/D conversion circuit and timing function, for example, a single chip microcomputer with a model of ATMGA88PA-AU may be used to sample and record output parameters of the power grid, where the output parameters of the power grid may include output voltage parameters, current parameters and frequency parameters, and sampling and recording interval time is set. For example, the sampling record interval time is set to 67 microseconds to achieve the purpose of timely detecting the power grid parameters, and meanwhile, the control unit can also timely judge whether the power grid voltage has a dip or not after detecting the power grid parameters. In one embodiment, there is provided a voltage sag compensation device including: the system comprises an output parameter acquisition module and a voltage sag compensation module of a power grid. Wherein:
and the output parameter acquisition module of the power grid is used for acquiring the output parameters of the power grid detected by the detection unit.
And the voltage sag compensation module is used for converting direct current output by the energy storage unit into alternating current to be output after determining that voltage sag occurs according to the output parameters of the power grid, coupling the output voltage with the voltage of the power grid, and supplying power to a load by using the coupled voltage.
In one embodiment, the apparatus further comprises:
and the output voltage adjusting module is used for determining a voltage sag compensation parameter when determining that the voltage sag occurs, and adjusting the output voltage by adopting sine pulse width modulation voltage regulation or phase-shifting voltage regulation in the bridge according to the voltage sag compensation parameter.
And the output parameter detection module of the power grid is used for carrying out phase-locked tracking on the power grid voltage and detecting the output parameter of the power grid in real time.
In the description of the present specification, reference to the terms "some embodiments," "other embodiments," "desired embodiments," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (10)
1. A voltage sag compensation device, the voltage sag compensation device comprising: the power grid comprises an energy storage unit for acquiring output voltage of a power grid and outputting direct current, an inversion unit for converting the input direct current into alternating current and outputting the alternating current, a boosting unit, a detection unit, a control unit, a first switch and a second switch;
one end of the energy storage unit, one end of the first switch, one end of the second switch and one end of the detection unit are connected with a power grid, the other end of the energy storage unit is connected with the input end of the inversion unit, the output end of the inversion unit is connected with the first input end of the boosting unit, the second input end of the boosting unit is connected with the other end of the second switch, and the other end of the first switch and the output end of the boosting unit are connected with a load; the other end of the detection unit and the control end of the inversion unit are connected with the control unit;
the detection unit is used for detecting output parameters of a power grid in real time by setting sampling and recording interval time, wherein the output parameters comprise voltage parameters, current parameters and frequency parameters and are output to the control unit, and the control unit is used for determining voltage sag compensation parameters according to the voltage parameters, the current parameters and the frequency parameters when the voltage sag appears according to the output parameters of the power grid, controlling the first switch to be opened and the second switch to be closed, regulating the output voltage of the inversion unit according to the voltage sag compensation parameters, and supplying power to a load after coupling the power grid voltage input by the power grid through the second switch and the output voltage regulated by the inversion unit by the boost unit;
and the control unit is used for controlling the first switch to be closed and the second switch to be opened when the fact that no voltage sag occurs is determined according to the output parameters of the power grid, and the power grid voltage output by the power grid through the first switch supplies power to a load.
2. The voltage sag compensation device according to claim 1, wherein the inverter unit is an inverter.
3. The voltage sag compensation device according to claim 1, wherein the energy storage unit is a voltage stabilizing capacitor or a super energy storage capacitor for storing and stabilizing a voltage input from a power grid.
4. The voltage sag compensation device of claim 1, wherein the energy storage unit is a voltage stabilizing capacitor, the device further comprising:
a rectifier connected between the grid and the regulated capacitor; the rectifier, the voltage stabilizing capacitor and the inversion unit form a back-to-back converter.
5. The voltage sag compensation device of claim 4, wherein the rectifier is any one of a half-wave rectifier, a full-wave bridge rectifier, or a voltage doubler rectifier.
6. The voltage sag compensation device of claim 1, wherein the first switch and the second switch are high efficiency ultra-thin switches.
7. The voltage sag compensation device according to claim 1, further comprising a filter unit, wherein the inverter unit is connected to the boost unit through the filter unit.
8. A voltage sag compensation method applied to a control unit of a voltage sag compensation device according to any one of claims 1 to 7, comprising:
the method comprises the steps of obtaining output parameters of a power grid detected by a detection unit through setting sampling record interval time, wherein the output parameters comprise voltage parameters, current parameters and frequency parameters;
according to the output parameters of the power grid, when the occurrence of voltage sag is determined, determining voltage sag compensation parameters, converting direct current output by an energy storage unit into alternating current to be output, adjusting output voltage according to the voltage sag compensation parameters, coupling the adjusted output voltage with the voltage of the power grid, supplying power to a load by using the coupled voltage, and when the occurrence of the voltage sag is determined, supplying power to the load according to the voltage output by the power grid.
9. The voltage sag compensation method according to claim 8, wherein the adjusting the output voltage according to the voltage sag compensation parameter includes:
and regulating the output voltage by adopting sine pulse width modulation voltage regulation or phase shifting voltage regulation in a bridge according to the voltage sag compensation parameters.
10. The voltage sag compensation method according to claim 8, comprising:
and the detection unit performs phase-locked tracking on the power grid voltage and detects the output parameters of the power grid in real time.
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| CN106451410B (en) * | 2016-11-16 | 2019-05-03 | 上海交通大学 | A kind of direct current dynamic electric voltage recovery device and restoration methods |
| CN206313449U (en) * | 2017-01-03 | 2017-07-07 | 深圳市科雷特能源科技股份有限公司 | A kind of voltage sag compensation device for single-phase equipment |
| CN206878465U (en) * | 2017-06-20 | 2018-01-12 | 郑州林高电气有限公司 | Dynamic compensating device temporarily drops in a kind of novel voltage |
| DE102017211356A1 (en) * | 2017-07-04 | 2019-01-10 | Siemens Aktiengesellschaft | Arrangement for compensating voltage dips in a power supply network and method for compensating voltage dips in a power supply network |
| CN207398834U (en) * | 2017-10-12 | 2018-05-22 | 深圳市三和电力科技有限公司 | A kind of series voltage compensation device based on Power Electronic Technique |
| CN207381981U (en) * | 2017-11-07 | 2018-05-18 | 昂顿科技（上海）有限公司 | Voltage dip compensation device |
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| CN110797878A (en) * | 2019-12-04 | 2020-02-14 | 国网江苏省电力有限公司南通供电分公司 | Voltage sag restorer based on sag depth selection judgment |
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