CN117318549A - Distribution parameter adjusting method of transformer and three-phase distribution transformer - Google Patents
Distribution parameter adjusting method of transformer and three-phase distribution transformer Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P13/00—Arrangements for controlling transformers, reactors or choke coils, for the purpose of obtaining a desired output
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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
- H02J3/01—Arrangements for reducing harmonics or ripples
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Abstract
The invention discloses a distribution parameter adjusting method of a transformer and a three-phase distribution transformer, and belongs to the technical field of electric energy transmission adjustment. The first regulating device determines a plurality of first suppression parameters according to the primary instantaneous current when the primary winding is adjusted to be in star connection. The second regulating means determines a plurality of second suppression parameters from the secondary instantaneous current when the primary winding is adjusted to a delta connection. The first regulating device and the second regulating device respectively inhibit harmonic current under different capacity states, so that the stability of load power supply is ensured. When the fundamental voltage is unstable, the third regulating device enters a discharge state to supply a compensation voltage to the transformer. In order to avoid the current voltage of the third regulating device being too low due to the deep dip of the fundamental voltage, the invention maintains the high-capacity state of the primary winding by adjusting the capacity interval, and improves the charging efficiency of the third regulating device.
Description
Technical Field
The invention relates to the technical field of electric energy transmission regulation, in particular to a power distribution parameter regulation method of a transformer and a three-phase power distribution transformer.
Background
Nonlinear loads such as a switching power supply, a frequency conversion device, controllable lamplight and the like on the load side of the power grid can generate harmonic current and pollute the power distribution network. The voltage fluctuation problem is caused by the continuous switching of the number of loads and the use of power generation equipment such as photovoltaic power and wind power at the input side of a power grid. Problems with these distribution parameters ultimately affect other high precision loads via transformer interfacing. Chinese patent application CN116805838A discloses a method for suppressing the harmonic wave of the output voltage of an inverter, which obtains the output voltage of the inverter after harmonic suppression based on the fundamental wave modulation signal and the harmonic compensation modulation signal. The inverter includes: the switching device, the inverter bridge, the output filter inductor and the output filter capacitor. This approach concentrates fundamental compensation and harmonic suppression in one inverter. In order to suppress harmonics on the input side of the power network, such compensation fundamental waves and suppression harmonics are usually fixedly connected to the high-voltage side of the three-phase transformer. As described in the applicant's prior patent application CN116667721B, in order to reduce the loss of the transformer, the transformer capacity can be adjusted according to the way the load power switches the windings. The existing fundamental wave compensation and harmonic suppression equipment at a fixed position cannot solve the problem of neutral point entering of the filter capacitor. Further, the prior art needs to solve the problem that the recharging speed of the time-based compensation power supply is too slow when the low-capacity access is performed. Accordingly, there is a need for further improvements in the art.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a power distribution parameter adjusting method of a transformer and a three-phase power distribution transformer, wherein harmonic suppression parameters are adjusted according to an access mode of a winding, and meanwhile, reference capacity is adjusted according to the voltage of a compensation power supply, so that the phase voltage of the winding is changed, and the charging efficiency of the compensation power supply in low voltage is ensured.
The technical scheme of the invention is realized as follows:
a method for adjusting a power distribution parameter of a transformer, comprising the steps of:
step 1: collecting phase voltage and phase current of a secondary winding, calculating apparent power S, and determining a capacity interval according to preset reference capacity;
step 2: if the apparent power S is smaller than the lower limit of the capacity interval, the transformer enters a low-capacity state, and enters step 3, if the apparent power S is larger than the upper limit of the capacity interval, the transformer enters a high-capacity state, and enters step 4, otherwise, the transformer enters step 5;
step 3: the primary winding is adjusted to be in star connection, the secondary winding is adjusted to be in parallel connection, a first regulating device is connected to the primary winding in parallel, primary instantaneous current is extracted, the first regulating device determines a plurality of first inhibition parameters according to the primary instantaneous current, and step 5 is carried out;
step 4: the primary windings are adjusted to be in triangular connection, the secondary windings are adjusted to be in series connection, a second regulating device is connected in parallel to the secondary windings, secondary instantaneous current is extracted, the second regulating device determines a plurality of second inhibition parameters according to the secondary instantaneous current, and step 5 is carried out;
step 5: acquiring the phase voltage of the secondary winding again, if the phase voltage of the secondary winding is smaller than the reference voltage, entering a step 6, otherwise, entering a step 7;
step 6: a third regulating device is connected in series on the compensation winding, and enters a discharge state to provide compensation voltage for the transformer until the phase voltage of the secondary winding is greater than or equal to the reference voltage;
step 7: if the phase voltage of the secondary winding is greater than the reference voltage, the current voltage U of the third regulating device is monitored 3 If the current voltage U 3 Below the first threshold U max A third regulating device is connected in series on the compensation winding, and the third regulating device enters a charging state;
step 8: if the current voltage U 3 Below the second threshold U min Adjusting the reference capacity S according to the current voltage 0 Returning to step 1.
In the invention, in step 3, a plurality of harmonic currents are extracted from a primary instantaneous current, the angular frequency of the harmonic currents is measured, at least one single-tuned filter unit is started, and a first suppression parameter of the single-tuned filter unit is determined.
In the invention, the first capacitor, the first inductor and the first resistor of the single-tuned filter unit are calculated according to the angular frequency of the phase voltage and the harmonic current of the primary winding, and the first suppression parameters comprise the capacitance value of the first capacitor, the inductance value of the first inductor and the resistance value of the first resistor.
In the present invention, in step 4, a plurality of harmonic currents are extracted from the secondary transient current, the angular frequency of the harmonic currents is measured, at least one double-tuned filter unit is started, and a second suppression parameter of the double-tuned filter unit is determined.
In the invention, in step 6, the compensation voltage and the phase angle at which the third regulating means supplies the compensation voltage to the transformer are calculated from the load power factor.
In the present invention, in step 8, the adjusted reference capacity S 0 '=(1-β(U min - U 3 )i 1 /S)×S 0 ，i 1 Beta is a preset charging efficiency coefficient for the phase current of the primary winding.
A three-phase distribution transformer according to a distribution parameter adjustment method of the transformer, comprising:
a primary winding, on which a first regulating device is connected in parallel, the first regulating device determining a plurality of first suppression parameters according to the primary instantaneous current if the apparent power is less than the lower limit of the capacity interval;
a secondary winding, wherein a second regulating device is connected in parallel with the secondary winding, and if the apparent power is larger than the upper limit of the capacity interval, the second regulating device determines a plurality of second inhibition parameters according to the secondary instantaneous current;
a compensation winding, a third regulating device is connected in series on the compensation winding, if the line voltage of the secondary winding is smaller than the reference voltage, the third regulating device enters a discharge state, wherein,
a controller configured to control the capacity S according to the reference capacity 0 Determining a capacity interval and according to the current voltage U of the third regulating device 3 Adjusting the reference capacity S 0 。
The invention also comprises a primary switch group and a secondary switch group which are respectively arranged on the primary winding and the secondary winding, wherein the first regulating device starts to work when the primary switch group is connected with the neutral line of the primary winding, and the second regulating device starts to work when the secondary switch group is connected with the neutral line of the secondary winding.
In the invention, the first adjusting device comprises a plurality of single-tuning filter units, the number of the single-tuning filter units is equal to the harmonic number of the primary instantaneous current, and the second adjusting device comprises a plurality of double-tuning filter units, and the number of the double-tuning filter units is smaller than the harmonic number of the secondary instantaneous current.
In the present invention, the third regulating device includes a storage battery, a compensation capacitor, a compensation inductance, a bidirectional converter, and an inverter.
The method for adjusting the distribution parameters of the transformer and the three-phase distribution transformer have the following beneficial effects: the first regulating device determines a plurality of first suppression parameters based on the primary instantaneous current when the primary winding is adjusted to a star connection. The second regulating means determines a plurality of second suppression parameters from the secondary instantaneous current when the primary winding is adjusted to a delta connection. The first regulating device and the second regulating device respectively inhibit harmonic current under different capacity states, so that the stability of load power supply is ensured. When the fundamental voltage is unstable, a compensation voltage is supplied by the third regulating device. In order to avoid the current voltage of the third regulating device being too low due to the deep dip of the fundamental voltage, the invention maintains the high-capacity state of the primary winding by adjusting the capacity interval, and the phase voltage of the primary winding in the high-capacity state is equal to the line voltage, thereby improving the charging efficiency of the third regulating device.
Drawings
FIG. 1 is a schematic diagram of instantaneous current in a secondary winding of a three-phase transformer;
FIG. 2 is a schematic diagram of instantaneous voltages of secondary windings of a three-phase transformer;
FIG. 3 is a circuit topology diagram of a method of adjusting the distribution parameters of the transformer of the present invention;
FIG. 4 is a flow chart of a method of adjusting the power distribution parameters of the transformer of the present invention;
FIG. 5 is a schematic diagram of the wiring of the primary and secondary windings of the present invention;
FIG. 6 is a schematic diagram of the phase angle of the generated compensation power supply of the present invention;
FIG. 7 is a block diagram of a three-phase distribution transformer according to the method of adjusting the distribution parameters of the transformer of the present invention;
FIG. 8 is a schematic diagram of the positional relationship of the primary winding, the secondary winding and the compensation winding of the present invention;
FIG. 9 is a schematic view of a first adjustment device of the present invention;
FIG. 10 is a schematic view of a second adjustment device of the present invention;
fig. 11 is a schematic view of a third adjustment device of the present invention.
Detailed Description
For a clearer understanding of the objects, technical solutions and advantages of the present application, the present application is described and illustrated below with reference to the accompanying drawings and examples.
The current and voltage states of the power grid are unstable under the influence of power generation equipment and nonlinear loads, and other loads on the circuit are damaged. Particularly, high-frequency harmonic current and phase voltage drop affect the operation of high-precision motors, electronic equipment and the like. As shown in fig. 1 and 2, the instantaneous current of the secondary winding of the transformer contains a disturbance of higher harmonics before filtering. The instantaneous voltage of the secondary winding for a partial period drops below the reference value.
Example 1
As shown in fig. 3 to 6, according to the access state of the transformer, the power distribution parameters are regulated by the first regulating device, the second regulating device and the third regulating device, so that the stability of the power grid is maintained. The high-voltage power grid and the low-voltage power grid are three-phase lines, and the high-voltage power grid reduces the phase voltage to 220v through a transformer and then transmits the phase voltage to a load of the low-voltage power grid. The invention relates to a power distribution parameter adjusting method of a transformer, which comprises the following steps of:
step 1: and collecting phase voltage and phase current of the secondary winding, calculating apparent power S, and determining a capacity section according to a preset reference capacity. Typically the secondary winding is divided into three sections of 30% turns, 35% turns and 35% turns. The parallel connection of the secondary windings means that the number of turns is 35% and the number of turns is 35%And is connected with 30% turns in series. When apparent power fluctuates around a reference capacity, in order to avoid frequent operation of a capacity-adjusting switch, the invention sets a capacity interval [ (1-lambda) S 0 ，(1+λ)S 0 When the apparent power is within the interval, the connection state of the windings is not switched. The reference capacity is usually preset to 0.62 times the rated capacity of the low-capacity access state, and λ is, for example, 0.05.
When the apparent power is calculated, the secondary instantaneous voltage and the secondary instantaneous current of the secondary winding are converted into the effective phase voltage and the phase current, and then the effective power of each phase is obtained and the apparent power is calculated. u (u) 2 (n) the secondary instantaneous voltage acquired for the nth sample, i 2 (n) is the n-th acquired secondary instantaneous current, the phase voltage of the secondary windingPhase current of secondary winding->. N is the sampling frequency, and N in the power frequency circuit can be 21. The sampling period is for example 1ms. Apparent power s= (P 21 +P 22 +P 23 )/3，P 21 、P 22 P 23 The effective power of each phase of the secondary winding is respectively.
Step 2: if the apparent power S is smaller than the lower limit of the capacity interval, the transformer enters a low-capacity state, and the step 3 is entered, if the apparent power S is larger than the upper limit of the capacity interval, the transformer enters a high-capacity state, and the step 4 is entered, otherwise, the step 5 is entered. At lower apparent power, the transformer reduces losses by reducing capacity. At higher apparent power, the transformer maintains the load operation by increasing capacity. In the present embodiment, the line voltage and line current of the primary winding in the high-capacity access state are both in the low-capacity access stateThe rated capacity is 3 times that of the low-capacity access state.
Step 3: the primary winding is adjusted to be in star connection, the secondary winding is adjusted to be in parallel connection, a first regulating device is connected to the primary winding in parallel, primary instantaneous current is extracted, the first regulating device determines a plurality of first inhibition parameters according to the primary instantaneous current, and step 5 is carried out. A plurality of harmonic currents are extracted from the primary instantaneous current, the angular frequency of the harmonic currents is measured, at least one single-tuned filter unit is started, and a first suppression parameter of the single-tuned filter unit is determined. The first suppression parameter comprises a capacitance value of the first capacitor, an inductance value of the first inductor and a resistance value of the first resistor. In this embodiment, the primary instantaneous current is sampled according to the DC FOCT system detection, and the primary instantaneous current is decomposed into a fundamental current and other harmonic currents of high frequencies, each of which has an angular frequency that is an integer multiple of the angular frequency of the fundamental current. A corresponding number of single-tuned filter units are activated for the angular frequencies of the different harmonic currents. The compensation capacity of each single-tuning filter unit is set through table lookup, and the capacitance value, the inductance value and the resistance value of the single-tuning filter unit are calculated according to the angular frequency of the harmonic current.
Step 4: the primary windings are adjusted to be in triangular connection, the secondary windings are adjusted to be in series connection, a second regulating device is connected in parallel to the secondary windings, secondary instantaneous current is extracted, the second regulating device determines a plurality of second inhibition parameters according to the secondary instantaneous current, and step 5 is carried out. And extracting a plurality of harmonic currents from the secondary instantaneous current, measuring the angular frequency of the harmonic currents, starting at least one double-tuned filter unit, and determining a second inhibition parameter of the double-tuned filter unit. The second adjusting device adopts the double-tuned filter unit, and the same double-tuned filter unit can inhibit two groups of harmonic waves with different angular frequencies, so that the cost of filtering at the low-voltage side is reduced. And calculating the capacitance value, the inductance value and the resistance value of the single-tuned filter unit according to the angular frequency of the harmonic current.
Step 5: and acquiring the phase voltage of the secondary winding again, if the phase voltage of the secondary winding is smaller than the reference voltage, entering a step 6, otherwise, entering a step 7. If the phase voltage of the secondary winding is less than the reference voltage, voltage compensation needs to be performed. In a capacity switching system, the secondary windings are always in star connection, and the phase voltage u of the secondary windings 2 =U 2 /=220v，U 2 Is the line voltage of the secondary winding.
Step 6: and a third regulating device is connected in series on the compensation winding, the third regulating device enters a discharge state, and compensation voltage is provided for the transformer until the phase voltage of the secondary winding is greater than or equal to the reference voltage. In one embodiment, the compensation voltage U 4 = u 0 -u 1 ，u 1 U is the current phase voltage of the secondary winding 0 The reference voltage for the secondary winding is, for example, 220v. In another embodiment, the effect of power factor and number of winding turns on the compensation voltage is considered. As shown in fig. 6, a coordinate system uoi is established. After the voltage drops, the direction of the compensation voltage and the phase current i of the secondary winding 1 Perpendicular. Then compensate the voltageCos θ is the load power factor. Phase angle α=pi/2-arccos (u) 0 /u 1 cos θ). The third adjusting means provides the transformer with a compensation voltage for the phase angle, which phase angle remains the same as the phase voltage before the drop, i.e. the reference voltage.
Step 7: if the phase voltage of the secondary winding is greater than the reference voltage, the current voltage U of the third regulating device is monitored 3 If the current voltage U 3 Below the first threshold U max And a third regulating device is connected in series on the compensation winding, and the third regulating device enters a charging state. If the phase voltage of the secondary winding is greater than the reference voltage, or the current voltage U 3 Below the first threshold U max If not, the following adjustment operation is not executed, and the process returns to the step 1.
After the fundamental voltage is recovered, the third regulating device exits the compensation. With the increase of the compensation times, the current voltage U of the third regulating device 3 And (3) lowering. First threshold U max Typically a nominal output voltage, a second threshold value U min The lower limit is compensated for voltages below the first threshold. In order to avoid that the current voltage of the third regulating means is too low, the third regulating means enters a charging state, charging from the transformer via the compensation winding.
Step 8: if the current voltage U 3 Below the second threshold U min Adjusting the reference capacity S according to the current voltage 0 Returning to step 1. Current voltage U 3 Below the second threshold U min If not, the following adjustment operation is not executed, and the process returns to the step 1. Because the third regulating device is connected to the transformer through the compensation winding, when the transformer enters a low-capacity state, the phase voltage of the primary winding is reduced, and the secondary winding keeps the voltage by increasing the number of turns of the coil, but the number of turns of the compensation winding is fixed, so that the charging efficiency of the third regulating device is reduced. The invention maintains the high capacity state of the primary winding by adjusting the reference capacity. Adjusted reference capacity S 0 '=(1-β(U min - U 3 )i 1 /S)×S 0 。i 1 For the phase current of the primary winding, β is a predetermined charging efficiency coefficient, and may be between 0.5 and 0.8 depending on the power rating of the third regulating device.
Example two
As shown in fig. 7 and 8, the three-phase distribution transformer according to the distribution parameter adjustment method of the transformer of the present embodiment includes: the device comprises a primary winding, a secondary winding, a compensation winding, a controller, a primary switch group, a secondary switch group, a voltage collector and a current collector. And a first regulating device is connected in parallel with the primary winding, and the first regulating device determines a plurality of first suppression parameters according to the primary instantaneous current if the apparent power is smaller than the lower limit of the capacity interval. And a second regulating device is connected in parallel with the secondary winding, and the second regulating device determines a plurality of second suppression parameters according to the secondary instantaneous current if the apparent power is larger than the upper limit of the capacity interval. And a third regulating device is connected in series on the compensation winding, and if the line voltage of the secondary winding is smaller than the reference voltage, the third regulating device enters a discharge state to provide compensation voltage for the transformer. The controller is an execution part of the power distribution parameter adjusting method. The controller is configured to respond to the reference capacity S 0 A capacity interval is determined. In order to avoid a reduction in the output voltage of the third regulating device caused by a deep drop in the fundamental phase voltage, the controller controls the third regulating device in accordance with the current voltage U of the third regulating device 3 Adjusting the reference capacity S 0 . The phase voltage in the high capacity state is equal to the line voltage, and the charging efficiency of the third regulating device can be improved. The voltage collector and the current collector collect the voltage instantaneous value and the current instantaneous value of the primary winding and the secondary winding, generate a waveform chart after the operations such as noise reduction and the like pretreatment, and calculate the corresponding phase voltage and phase current.
Referring to fig. 5, the primary switch group and the secondary switch group are each composed of a plurality of linked switches. If for the primary switch group, switch k11 is closed and switch k12 is open; for the secondary switch group, the switch k21 is closed, the switch k22 and the switch k23 are opened, so that the primary windings of the transformer are connected in a delta shape, and the secondary windings are connected in series, and the transformer is in a high-capacity access state. In the high capacity state, the neutral point of the primary winding is in an off state. If for a primary switch bank, switch k11 is open and switch 12 is closed; for the secondary switch group, the switch k21 is opened, the switch k22 and the switch k23 are closed, the primary winding of the transformer can be connected in star, and the secondary winding is connected in parallel, and is in a low-capacity access state at the moment. In addition, the primary switch group and the secondary switch group can also be used for switching on and off the first adjusting device and the second adjusting device. When the primary switch group is connected with the neutral line of the primary winding, the first regulating device starts to work, and when the secondary switch group is connected with the neutral line of the secondary winding, the second regulating device starts to work. The filtering branches of the first regulating device and the second regulating device are all in star connection, and the filtering branches are connected with neutral wires of corresponding windings in order to keep unity with current parameters of the windings. Under the premise of ensuring that the filtering branch in operation is connected with the corresponding neutral line, harmonic current suppression can be completed at the high voltage side as much as possible, so that the influence of the regulating device on the low-voltage power grid is reduced.
Example III
The present embodiment further describes the first adjusting device and the second adjusting device with reference to fig. 9 and 10. The first adjusting device comprises a plurality of single-tuning filter units, the number of the single-tuning filter units is equal to the harmonic number of the primary instantaneous current, and the second adjusting device comprises a plurality of double-tuning filter units, and the number of the double-tuning filter units is smaller than the harmonic number of the secondary instantaneous current. The first regulating device and the second regulating device respectively inhibit harmonic current under different voltage states, so that the stability of load power supply is ensured. Each single-tuned filter unit is composed of three groups of first filter branches in star connection, and each first filter branch is connected to each phase of the primary winding. The first filtering branch circuit consists of a first inductor, a first capacitor and a first resistor which are connected in series, and the first inductor and the first capacitor are utilized to resonate at harmonic current of specific times and absorb the harmonic current.
The angular frequency omega of the fundamental wave current is a fixed value and is determined by the operating frequency of the high-voltage power grid. For harmonic currents of order mω, m is an integer greater than 1. The invention controls the first suppression parameter of the first filtering branch of the single tuning filter unit so as to suppress the harmonic current, and distributes reactive compensation capacity Q to the corresponding single tuning filter unit 1 . First, the capacitance C of the first capacitor is determined 1 =Q 1 /(mωu 1 2 )。u 1 Is the phase voltage of the primary winding. Determining the inductance value L of the first inductor 1 =1/(m 2 ω 2 C 1 ). Resistance value r= (mωl) of first resistor 1 ) And/q. q is the quality factor of the first filtering branch, and is generally selected to be 30-60. Finally, the harmonic current of m omega times is filtered through the first filtering branch. Impedance Z of the first filtering branch 1 =R+j［mωL 1 -1/(mωC 1 ) J is an imaginary number, i.e. j 2 =-1。
Each double-tuned filter unit is composed of three groups of star-connected second filter branches, and each second filter branch is connected with each phase of the secondary winding. In the second filtering branch, the third inductor is connected with the third capacitor in parallel and then connected with the second inductor and the second capacitor in series. The voltage of the secondary winding is lower and is directly connected with the high-precision load in parallel. The double-tuned filter unit has small power loss, only the second inductance connected in series bears all impulse voltages, and the third capacitance only passes through harmonic reactive capacity, so that the normal operation of load side equipment can be prevented from being influenced by filter operation. In effect, the double-tuned filter unit absorbs harmonic currents with two different angular frequencies at the same time, and the filter efficiency is improved. After the total reactive compensation capacity of the second adjusting device is determined, the reactive compensation capacity is allocated to each double-tuned filter unit, and then the second inhibition parameters of the double-tuned filter units are designed. In this embodiment, the reactive compensation capacity is allocated on the condition that the inductance values of the second harmonic branches are equal. In further embodiments, equal capacitance distribution conditions or minimum inductance distribution conditions may also be employed depending on the design requirements of the load.
For a number of times of m 1 Omega and m 2 Two harmonic currents of ω, m 1 And m 2 Is an integer greater than 1. The invention controls the second suppression parameter of the second filter branch of the double-tuned filter unit so as to suppress the harmonic current, and the reactive compensation capacity distributed to the double-tuned filter unit is Q 2 . First, the capacitance C of the second capacitor is determined 2 =Q 2 /(ωu 2 2 ) Capacitance value C of the third capacitor 3 =C 2 m 1 m 2 /(m 1 -m 2 ) 2 。u 2 Is the phase voltage of the secondary winding. Determining the inductance value L of the second inductor 2 =1/(m 1 m 2 ω 2 C 2 ) Inductance value L of third inductor 3 =1/(m 1 m 2 ω 2 C 3 ). Finally, m is filtered by the second filtering branch 1 Omega and m 2 Two harmonic currents of ω.
Example IV
As shown in fig. 11, the present embodiment further discloses a third adjusting device, which includes a storage battery, a compensation capacitor, a compensation inductor, a bidirectional converter and an inverter. The storage battery and the compensation capacitor are used as a compensation power supply together, the current voltage of the third regulating device is an output value of the storage battery and the compensation capacitor after being connected in parallel, and the rated power of the storage battery and the capacitance value of the compensation capacitor can be set according to the running environment of the transformer. The bidirectional converter has two working modes, namely Buck and Boost. In Boost mode, the battery and the compensation capacitor enter a discharge state. PWM device of controller individually controls power device G 1 During operation, the storage battery and the compensation capacitor charge and store energy for the compensation inductor. In Buck mode of operation, the PWM device individually controls powerDevice G 2 In operation, the storage battery, the compensation capacitor and the compensation inductor provide compensation voltage for the compensation winding. Wherein, the power device G 1 And power device G 2 The two electrodes are mutually conducted in one switching period, so that the control of the compensation voltage can be realized in real time. The invention determines the compensation voltage according to the line voltage of the primary winding so as to compensate the part of the line voltage which is smaller than the reference voltage. At the same time, the phase angle of the line voltage is tracked, and finally the compensation voltage and the phase angle are determined. Further, the present invention converts direct current of a battery or the like into alternating current by an inverter. The smoothed sine wave compensation voltage is generated via an inverter controlled by another PWM device of the controller.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (10)
1. A method for adjusting a power distribution parameter of a transformer, comprising the steps of:
step 1: collecting phase voltage and phase current of a secondary winding, calculating apparent power S, and determining a capacity interval according to preset reference capacity;
step 2: if the apparent power S is smaller than the lower limit of the capacity interval, the transformer enters a low-capacity state, and enters step 3, if the apparent power S is larger than the upper limit of the capacity interval, the transformer enters a high-capacity state, and enters step 4, otherwise, the transformer enters step 5;
step 3: the primary winding is adjusted to be in star connection, the secondary winding is adjusted to be in parallel connection, a first regulating device is connected to the primary winding in parallel, primary instantaneous current is extracted, the first regulating device determines a plurality of first inhibition parameters according to the primary instantaneous current, and step 5 is carried out;
step 4: the primary windings are adjusted to be in triangular connection, the secondary windings are adjusted to be in series connection, a second regulating device is connected in parallel to the secondary windings, secondary instantaneous current is extracted, the second regulating device determines a plurality of second inhibition parameters according to the secondary instantaneous current, and step 5 is carried out;
step 5: acquiring the phase voltage of the secondary winding again, if the phase voltage of the secondary winding is smaller than the reference voltage, entering a step 6, otherwise, entering a step 7;
step 6: a third regulating device is connected in series on the compensation winding, and enters a discharge state to provide compensation voltage for the transformer until the phase voltage of the secondary winding is greater than or equal to the reference voltage;
step 7: if the phase voltage of the secondary winding is greater than the reference voltage, the current voltage U of the third regulating device is monitored 3 If the current voltage U 3 Below the first threshold U max A third regulating device is connected in series on the compensation winding, and the third regulating device enters a charging state;
step 8: if the current voltage U 3 Below the second threshold U min Adjusting the reference capacity S according to the current voltage 0 Returning to step 1.
2. The method of adjusting a power distribution parameter of a transformer according to claim 1, wherein in step 3, a plurality of harmonic currents are extracted from the primary instantaneous current, an angular frequency of the harmonic currents is measured, at least one single-tuned filter unit is started, and a first suppression parameter of the single-tuned filter unit is determined.
3. The method for adjusting a power distribution parameter of a transformer according to claim 2, wherein the first capacitor, the first inductor and the first resistor of the single-tuning filter unit are calculated according to angular frequencies of phase voltages and harmonic currents of the primary winding, and the first suppression parameter includes a capacitance value of the first capacitor, an inductance value of the first inductor and a resistance value of the first resistor.
4. The method of claim 1, wherein in step 4, a plurality of harmonic currents are extracted from the secondary instantaneous current, the angular frequency of the harmonic currents is measured, at least one double-tuned filter unit is activated, and a second suppression parameter of the double-tuned filter unit is determined.
5. A method of adjusting a distribution parameter of a transformer according to claim 1, characterized in that in step 6, the compensation voltage and the phase angle are calculated from the load power factor, at which phase angle the third adjusting means supplies the compensation voltage to the transformer.
6. The method for adjusting the distribution parameters of a transformer according to claim 1, wherein in step 8, the adjusted reference capacity S 0 '=(1-β(U min - U 3 )i 1 /S)×S 0 ，i 1 Beta is a preset charging efficiency coefficient for the phase current of the primary winding.
7. A three-phase distribution transformer according to a distribution parameter adjustment method of a transformer according to claim 1, characterized by comprising:
a primary winding, on which a first regulating device is connected in parallel, the first regulating device determining a plurality of first suppression parameters according to the primary instantaneous current if the apparent power is less than the lower limit of the capacity interval;
a secondary winding, wherein a second regulating device is connected in parallel with the secondary winding, and if the apparent power is larger than the upper limit of the capacity interval, the second regulating device determines a plurality of second inhibition parameters according to the secondary instantaneous current;
a compensation winding, a third regulating device is connected in series on the compensation winding, if the line voltage of the secondary winding is smaller than the reference voltage, the third regulating device enters a discharge state, wherein,
a controller configured to control the capacity S according to the reference capacity 0 Determining a capacity interval and according to the current voltage U of the third regulating device 3 Adjusting the reference capacity S 0 。
8. The three-phase distribution transformer of claim 7 further comprising a primary switch set and a secondary switch set mounted to the primary winding and the secondary winding, respectively, the primary switch set being configured to operate when the primary switch set is connected to the neutral line of the primary winding and the secondary switch set being configured to operate when the secondary switch set is connected to the neutral line of the secondary winding.
9. The three-phase distribution transformer according to claim 7, wherein the first regulating means comprises a plurality of single-tuned filter units, the number of single-tuned filter units being equal to the number of harmonics of the primary instantaneous current, and the second regulating means comprises a plurality of double-tuned filter units, the number of double-tuned filter units being smaller than the number of harmonics of the secondary instantaneous current.
10. The three-phase distribution transformer of claim 7 wherein the third regulation device comprises a battery, a compensation capacitor, a compensation inductance, a bi-directional converter, and an inverter.
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Denomination of invention: A method for adjusting distribution parameters of a transformer and a three-phase distribution transformer Granted publication date: 20240126 Pledgee: Jiangxi Bank Co.,Ltd. Nanchang Xinjian Branch Pledgor: JIANGXI NO.2 ELECTRIC POWER EQUIPMENT Co.,Ltd. Registration number: Y2024980033663 |
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