Single-phase non-coupling transformer split source depth compensation series active voltage quality regulator

Abstract

A single-phase non-coupling transformer split source depth compensation series active voltage quality regulator comprises a rectification unit, an inversion unit, a filtering unit and a bypass unit, and is used for realizing depth compensation of AC voltage. According to the invention, through the inversion unit, only two diodes and four power tubes are used, the boost and inversion functions can be realized at the same time, the demand for power electronic devices is low, the compensation range of the active voltage quality regulator can be enlarged, the realization method is simple, and the cost is lower.

Description

Technical Field

[0001] The invention relates to the technical field of power quality management, and in particular to a single-phase non-coupling transformer split-source deep compensation series active voltage quality regulator. Background Art

[0002] With the development of modern science and technology and the continuous improvement of production and living standards, various sophisticated, complex, and voltage-sensitive electrical equipment have become increasingly popular, such as high-performance home appliances, office equipment, precision experimental instruments, and automatic control equipment for continuous precision production. Electricity users have increasingly higher requirements for voltage quality, and power supply technology has shifted from the quantity stage to the quality stage. The quality of voltage is directly related to the overall benefits of the national economy.

[0003] At the same time, the development of new energy has also brought people clean and reliable energy supply. However, the large-scale access of new energy equipment also threatens the voltage quality of the power grid. This requires a voltage quality compensation device to compensate the grid voltage and ensure the quality of the power supply of the grid.

[0004] The compensation depth is one of the main indicators for determining the performance of the voltage quality compensation device. In fact, the grid voltage will drop to different depths. When the grid voltage drops more deeply, the compensation device needs to have a deeper compensation depth. For the existing DySC topology and the back-to-back PB-AVQR topology, collectively referred to as the half-bridge transformerless topology, its performance is limited, the compensation capability is insufficient, and many power tubes are required, which is not cheap. The DVR needs to provide an energy storage device separately, which increases the cost and volume. Research on series active voltage quality regulators (AVQRs) with deep compensation capabilities is still a rigid demand.

[0005] The compensation range of the prior art is limited by topology and other reasons, and the maximum compensation depth does not exceed 50%. Summary of the invention

[0006] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a single-phase uncoupled transformer split source deep compensation series active voltage quality regulator, which can simultaneously realize the boost and inversion functions through an inverter unit, using only two diodes and four power tubes, with less demand on power electronic devices and a simple implementation method; the present invention can increase the compensation range of the active voltage quality regulator and has lower cost.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A single-phase non-coupling transformer split source deep compensation series active voltage quality regulator comprises a rectifier unit, an inverter unit, a filter unit and a bypass unit to achieve deep compensation of AC voltage; wherein:

[0009] The rectifier unit includes a rectifier VZ, a decoupling transformer T1 and an energy storage capacitor C1 connected in series in sequence; the rectifier VZ converts AC power into DC power, and the electric energy is temporarily stored in the energy storage capacitor C1; when the grid has a voltage quality problem, the grid voltage charges the energy storage capacitor C1 through the decoupling transformer T1 and the rectifier VZ, providing energy for AVQR to inject a compensation voltage into the grid;

[0010] The inverter unit adopts a split source inverter: it includes a boost inductor L1, a boost capacitor C2, two parallel diodes D1, D2 and four power tubes S1, S2, S3, S4, which are connected in series in sequence to form an inverter full bridge; when it is necessary to inject compensation voltage into the grid, the inverter unit, driven by the hybrid SPWM control signal, inverts the DC voltage on the energy storage capacitor C1 into the required compensation voltage to compensate for the drop of the grid voltage;

[0011] Filter unit: a low-pass passive filter consisting of a filter inductor L3 and a filter capacitor C3, wherein one end of the filter inductor L3 is connected to the cathode of the diode D1 or the emitter of the power tube S1 and the collector of the power tube S2, and the other end is connected to the filter capacitor C3; the other end of the filter capacitor C3 is connected to the load;

[0012] Bypass unit: It consists of a contactor KM1 connected after the roadside capacitor and a pair of anti-parallel thyristors KV1 and KV2 in parallel; the bypass unit performs the operation of switching the AVQR on and off; since the bypass unit is responsible for switching the AVQR on and off, the response time of the bypass unit directly determines the AVQR operation switching time.

[0013] In the rectifier unit, the rectifier VZ adopts an uncontrolled rectifier bridge.

[0014] The filtering unit adopts a low-pass passive LC filter; when working, the higher harmonics other than the fundamental frequency will be filtered out by the filtering unit.

[0015] The inverter unit is equivalently divided into a BOOST part and a full-bridge inverter part. The inverter unit is divided into the following four working modes according to the positive half cycle and negative half cycle of the output voltage under the hybrid SPWM modulation of the power tube conduction timing:

[0016] Mode 1t 0 ~t 1 stage:

[0017] The BOOST part is capacitor C1, diode D2 and power tube S4 connected in series, and the full-bridge inverter part is an inverter full-bridge composed of capacitor C2 and four power tubes:

[0018] In t 0Before the moment, the power tubes S1 and S3 are turned on, and the boost inductor L1 is subjected to reverse pressure (V c3 -V c1 ) and linear discharge; at t 0 At this moment, the power tube S3 is turned off, the power tube S2 remains off, and the power tubes S1 and S4 are turned on. 1 The moment is over;

[0019] In t 0 ~t 1 In the range, for the BOOST part, that is, capacitor C1, diode D2 and power tube S4 are connected in series; diode D2 is turned on, and inductor L1 is subjected to forward voltage V c1 And store energy, the inductor current i L1 Linear rise;

[0020]

[0021] In t 0 ~t 1 In the range, the full-bridge inverter part, i.e., the full-bridge inverter composed of capacitor C2 and four power tubes, has a filter inductor current i L2 It flows through power tube S1 and power tube S4, so:

[0022]

[0023] Mode 2t 1 ~t 2 stage:

[0024] In t 1 At this moment, the full-bridge inverter part in the inverter unit, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, form an inverter full-bridge. The power tube S1 is turned off, the power tube S3 remains off, and the power tubes S2 and S4 are turned on. 2 The moment is over;

[0025] In t 1 ~t 2 In the range, for the BOOST part, i.e., capacitor C1, diode D1 is connected in series with power tube S2, diode D2 is cut off, the voltage across diode D2 is clamped to zero, diode D1 is turned on, and boost inductor L1 is subjected to forward voltage V C1 , inductor current i L1 Continue to maintain a linear rise;

[0026]

[0027] In t 1 ~t 2In the interval, the full-bridge inverter part, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, form an inverter full-bridge. The inductor current iL2 of the full-bridge inverter part is freewheeling through the power tubes S2 and S4, and the inductor L2 releases energy. Therefore, there is:

[0028]

[0029] Mode 3t 2 ~t 3 stage:

[0030] t 2 At this moment, the power tubes S2 and S3 in the inverter unit are turned off, and the power tubes S1 and S4 are turned on. 3 The moment ends, the working process is the same as t 0 ~t 1 The stages are the same;

[0031]

[0032] Mode 4t 3 ~t 4 stage:

[0033] In t 3 At this moment, the power tube S4 in the inverter unit is turned off, and the power tubes S1 and S3 are turned on. 4 At the end of the moment, the boost inductor L1 releases energy during this period, which affects the bus capacitor C 2 Charging; repeat the above process in the next switching cycle;

[0034] In t 3 ~t 4 In the BOOST section, capacitor C1, diode D1, power tube S1 and capacitor C2 are connected in series, diode D2 is cut off, and diode D 2 The voltage at both ends is clamped to zero, the diode D1 is turned on, the inductor current iL1 is continued through the power tube S1, and the two ends of the inductor L1 are subjected to the reverse voltage (V C2 -V C1 ), the inductor current iL1 decreases linearly:

[0035]

[0036] In t 3 ~t 4 In the interval, the inductor current iL2 of the full-bridge inverter part, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, is continuous through the power tubes S1 and S3, so:

[0037]

[0038] The specific method of the inverter unit, under the drive of the hybrid SPWM control signal, inverting the DC voltage on the energy storage capacitor C1 into the required compensation voltage to compensate for the drop of the grid voltage is:

[0039] Inverter unit boost inductor L 1 In t 0 ~t 3 Charging within the time period, at t 3 ~t 4 Discharge during the time period, the DC boost duty cycle is:

[0040]

[0041] From the relationship between the input voltage and output voltage of the inverter unit BOOST part, we know that the inverter bus voltage is V C2 for:

[0042] V C2 =V C1 / (1-D dc ) (9)

[0043] The output voltage of the full-bridge inverter and the bus voltage satisfy the following relationship:

[0044] v o_pk =M ac V C2 (10)

[0045] Where Ts is the switching period, V o_pk is the inverter output sinusoidal voltage amplitude, M ac is the SPWM modulation ratio;

[0046] Therefore, the relationship between the inverter unit output voltage and input voltage is:

[0047]

[0048] The boost ratio of the inverter unit is M ac is the SPWM modulation ratio, D dc is the DC boost duty cycle. In order to prevent over-modulation of harmonic distortion, the SPWM modulation ratio M ac Limit the DC boost duty cycle D dc ;

[0049] Output voltage V out With input voltage V in , compensation voltage between V o_pk The relationship is:

[0050] V out =V in +V o_pk (12)

[0051] Output voltage V out With reference standard voltage V ref The same, that is, V out =V ref , that is, the output voltage V out The peak value is 311V;

[0052] The input voltage Vin is rectified after the rectifier unit to obtain the rectified voltage V C1 , the relationship between the two is:

[0053] V in =3.9946V C1 (13)

[0054] After passing through the inverter unit, the compensation voltage V is obtained, that is:

[0055]

[0056] After sorting, we can get the input voltage V in With reference standard voltage V ref The relationship between them is as follows:

[0057]

[0058] Assume the compensation depth is G, then

[0059]

[0060] According to formula (16), the compensation depth G increases with the DC boost duty cycle D dc and SPWM modulation ratio M ac increases with the increase of; due to the SPWM modulation ratio M ac Limit the DC boost duty cycle D dc , let M ac =D dc ,have to:

[0061]

[0062] Therefore, G = f(D dc ), in Matlab, draw the function curve.

[0063] Compared with the prior art, the present invention has the following advantages:

[0064] 1) The present invention can simultaneously realize the boost and inversion functions through an inverter unit with only two diodes D1 and D2 and four power tubes S1, S2, S3 and S4, with less demand on power electronic devices, lower cost and simple implementation method.

[0065] 2) During operation, the inverter unit of the present invention realizes boosting and inversion simultaneously, and the boost ratio G (as shown in formula (17)) can reach up to 69% at most. It has the ability to deeply compensate for the AC voltage. Compared with the prior art, the range of the compensated voltage is wider.

[0066] 3) The inverter unit of the present invention has four working modes, and uses a common full-bridge power tube to achieve boost and inversion, thereby reducing the number of power tubes in the circuit and reducing costs; at the same time, only when the power tubes S1 and S3 are both turned on, the inductor L 1 Only then will the energy be released to the bus capacitor C 2 Charge.

[0067] In summary, the present invention realizes boosting and inversion by sharing full-bridge power tubes in the inverter unit, thereby reducing the number of power tubes in the circuit and reducing costs; it has the ability to compensate for deep voltage drops. The present invention creatively combines the split source inverter into the AVQR, so that the present invention can achieve more than 50% deep compensation without significantly increasing the number of power electronic devices, and the compensable voltage drop range is wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 This is a single-phase non-coupling transformer series active voltage quality regulator topology of the present invention.

[0069] Figure 2 It is a schematic diagram of the inverter unit principle of the present invention.

[0070] Figure 3 is the working mode 1 of the present invention, Figure 3(a) is the overall circuit, Figure 3(b) is the BOOST part of the equivalent circuit of the working mode 1 of the present invention, and Figure 3(c) is the full-bridge inverter part of the equivalent circuit of the working mode 1 of the present invention.

[0071] Figure 4 is the working mode 2 of the present invention, Figure 4(a) is the overall circuit, Figure 4(b) is the BOOST part of the equivalent circuit of the working mode 2 of the present invention, and Figure 4(c) is the full-bridge inverter part of the equivalent circuit of the working mode 2 of the present invention.

[0072] Figure 5 is the working mode 3 of the present invention, Figure 5(a) is the overall circuit, Figure 5(b) is the BOOST part of the equivalent circuit of the working mode 3 of the present invention, and Figure 5(c) is the full-bridge inverter part of the equivalent circuit of the working mode 3 of the present invention.

[0073] Figure 6 is the working mode 4 of the present invention, Figure 6(a) is the overall circuit, Figure 6(b) is the BOOST part of the equivalent circuit of the working mode 4 of the present invention, and Figure 6(c) is the full-bridge inverter part of the equivalent circuit of the working mode 4 of the present invention.

[0074] Figure 7 This is the compensation voltage curve of the present invention.

[0075] Figure 8 This is the simulation model of the present invention.

[0076] Figure 9(a) shows (U AC =180V) voltage waveform after compensation, Figure 9(b) is (U AC =180V) voltage distortion after compensation.

[0077] Figure 10(a) shows the AC =150V) voltage waveform after compensation, Figure 10(b) is (U AC =150V) voltage distortion after compensation.

[0078] Figure 11(a) shows (U AC =110V) voltage waveform after compensation, Figure 11(b) is (U AC =110V) voltage distortion after compensation.

[0079] Figure 12(a) shows (U AC =80V) voltage waveform after compensation, Figure 12(b) is (U AC =80V) voltage distortion after compensation. DETAILED DESCRIPTION

[0080] The present invention is further described in detail below with reference to the accompanying drawings.

[0081] See also Figure 1 , a single-phase non-coupling transformer split source deep compensation series active voltage quality regulator, based on a topological structure, including a rectifier unit, an inverter unit, a filter unit and a bypass unit, to achieve deep compensation of AC voltage; wherein:

[0082] The rectifier unit includes a rectifier VZ, a decoupling transformer T1 and an energy storage capacitor C1 connected in series in sequence; the rectifier VZ converts AC power into DC power, and the electric energy is temporarily stored in the energy storage capacitor C1; when the grid has a voltage quality problem, the grid voltage charges the energy storage capacitor C1 through the decoupling transformer T1 and the rectifier VZ, providing energy for AVQR to inject a compensation voltage into the grid;

[0083] The inverter unit adopts a split source inverter: it includes a boost inductor L1, a boost capacitor C2, two parallel diodes D1, D2 and four power tubes S1, S2, S3, S4, which are connected in series in sequence to form an inverter full bridge; when it is necessary to inject compensation voltage into the grid, the inverter unit, driven by the hybrid SPWM control signal, inverts the DC voltage on the energy storage capacitor C1 into the required compensation voltage to compensate for the drop of the grid voltage and maintain the grid voltage of 1 in the normal working state;

[0084] Filter unit: a low-pass passive filter consisting of a filter inductor L3 and a filter capacitor C3, wherein one end of the filter inductor L3 is connected to the cathode of the diode D1 or the emitter of the power tube S1 and the collector of the power tube S2, and the other end is connected to the filter capacitor C3; the other end of the filter capacitor C3 is connected to the load;

[0085] Bypass unit: It consists of a contactor KM1 connected after the roadside capacitor and a pair of anti-parallel thyristors KV1 and KV2 in parallel; the bypass unit performs the operation of switching the AVQR on and off; since the bypass unit is responsible for switching the AVQR on and off, the response time of the bypass unit directly determines the AVQR operation switching time.

[0086] In the rectifier unit, the rectifier VZ adopts an uncontrolled rectifier bridge.

[0087] The filtering unit adopts a low-pass passive LC filter; when working, the higher harmonics other than the fundamental frequency will be filtered out by the filtering unit.

[0088] The working regulation method of the inverter unit in the single-phase non-coupling transformer split source deep compensation series active voltage quality regulator is divided into the following four modes according to the power tube conduction timing under hybrid SPWM modulation:

[0089] The inverter topology derivation process is as follows: Figure 2 As shown in the figure, the split-source inverter is a single-stage inverter evolved from the BOOST converter and the voltage source full-bridge inverter. Compared with the two-stage inverter structure, the split-source inverter can achieve boost and inversion at the same stage (see the analysis below for proof), reducing system cost and complexity, and also improving system integration.

[0090] The following is a modal analysis of the invented single-phase non-coupling transformer split source deep compensation series active voltage quality regulator when working in combination with the previous topology. The power tube conduction timing of the invented device under hybrid SPWM modulation is as follows:

[0091] Table 1. Power tube conduction timing

[0092]

[0093] (1)t 0 ~t 1 stage:

[0094] In t 0 Before the moment, the power tubes S1 and S3 are turned on, and the boost inductor L1 discharges linearly due to the reverse voltage (Vc3-Vc1). 0 At this moment, the power tube S3 is turned off, and the power tubes S1 and S4 are turned on. 1 The moment ends, as shown in Figure 3.

[0095] In t 0 ~t 1 In the range, for the BOOST part (capacitor C1, diode D2 and power tube S4 in series), diode D2 is turned on, and inductor L1 is subjected to the forward voltage V c1 And store energy, the inductor current i L1 Linear rise;

[0096]

[0097] The filter inductor current i of the full-bridge inverter part (composed of capacitor C2 and inverter full bridge, the same below) L2 It flows through power tube S1 and power tube S4, so:

[0098]

[0099] (2)t 1 ~t 2 stage:

[0100] t 1 At this moment, the power tube S1 is turned off, and the power tubes S2 and S4 are turned on. 2 The moment ends, as shown in FIG4 .

[0101] In this range, for the BOOST part, diode D2 is cut off, the voltage across diode D2 is clamped to zero, diode D1 is turned on, and L1 is subjected to the forward voltage V C1 ,i L1 Continue to rise linearly.

[0102]

[0103] For the full-bridge inverter part, i L2 Through the continuous flow of power tubes S2 and S4, L2 releases energy, so:

[0104]

[0105] (3)t 2 ~t 3 stage:

[0106] t 2 At this moment, the power tube S2 is turned off, and the power tubes S1 and S4 are turned on. 3 The time ends, and this working process is the same as t 0 ~t 1 The stages are the same, as shown in Figure 5.

[0107]

[0108] (4)t 3~t 4 stage:

[0109] In t 3 At this moment, the power tube S4 is turned off, and the power tubes S1 and S3 are turned on. 4 The moment ends, during which the boost inductor L1 releases energy and charges the bus capacitor C2, as shown in Figure 6. The above process is repeated in the next switching cycle.

[0110] In the BOOST part, diode D2 is cut off, the voltage across diode D2 is clamped to zero, and diode D1 is turned on. L1 The power tube S1 is used for freewheeling, and the two ends of the inductor L1 are subjected to reverse pressure (V C2 -V C1 ),i L1 Linear decrease.

[0111]

[0112] In the full-bridge inverter part, i L2 The current is continued through power tubes S1 and S3, so:

[0113]

[0114] From the above working mode analysis, it can be seen that the invented product realizes boost and inversion by sharing the full-bridge power tube, thereby reducing the number of power tubes in the circuit and reducing costs. At the same time, only when the power tubes S1 and S3 are both turned on, the inductor L1 releases energy to charge the bus capacitor C2.

[0115] From the above analysis, we can see that the inductor L1 is 0 ~t 3 Charging within the time period, at t 3 ~t 4 Discharge in the time period, so the DC boost duty cycle can be obtained as:

[0116]

[0117] From the relationship between the input voltage and output voltage of the BOOST converter, we can know that the inverter bus voltage is V C2 for:

[0118] V C2 =V C1 / (1-D dc ) (9)

[0119] The output voltage of the full-bridge inverter and the bus voltage satisfy the following relationship:

[0120] v o_pk =M ac V C2 (10)

[0121] Where Ts is the switching period, V o_pk is the inverter output sinusoidal voltage amplitude, M ac is the SPWM modulation ratio.

[0122] Therefore, the relationship between the inverter unit output voltage and input voltage is:

[0123]

[0124] The boost ratio of the inverter unit is (M ac is the SPWM modulation ratio, D dc is the DC boost duty cycle), in order to prevent overmodulation of harmonic distortion ac Restricted to D dc Its advantages are single-stage boost inverter, continuous input current, and common ground of input voltage source and inverter bridge; it has a more compact structure and lower device cost, can maintain a high modulation factor while obtaining a high output voltage gain, and achieve a high output voltage gain while ensuring the quality of high voltage waveform.

[0125] Considering the overall circuit, the relationship between the output voltage and the input voltage and the compensation voltage is:

[0126] V out =V in +V o_pk (12)

[0127] The output voltage is the same as the reference standard voltage, that is, V out =V ref , that is, the peak value of the output voltage is 311V.

[0128] The input voltage Vin is rectified after the rectifier unit to obtain the rectified voltage V C1 , the relationship between the two is:

[0129] V in =3.9946V C1 (13) After passing through the inverter unit, the compensation voltage V is obtained, that is:

[0130]

[0131] After sorting, the relationship between the input voltage and the standard voltage can be obtained as follows:

[0132]

[0133] Assume the compensation depth is G, then

[0134]

[0135] According to formula (16), the compensation depth G increases with D dc ,M ac increases with the increase of M ac Restricted to D dc , let M ac =D dc ,have to:

[0136]

[0137] Therefore, G = f(D dc ), in Matlab, draw the function curve.

[0138] Depend on Figure 7 It can be seen that the maximum compensation depth can reach 69% in theory. However, in reality, the DC duty cycle D dc Generally, it will not be very high, so the actual maximum compensation depth can reach about 65%, which exceeds the maximum compensation depth of 50% in the existing technology, can compensate for the voltage depth drop, and expand the range of voltage compensation.

[0139] Build a simulation model in Matlab / Simulink for verification. The model is built as follows Figure 8 ;

[0140] When the voltage temporarily drops to the effective value of 180V, the compensation result is shown in Figure 9: THD = 1.66%, which shows that the compensation effect of the present invention is good. Compared with the prior art, the present invention also has the ability to compensate voltage when the power supply voltage drops slightly to 81.8% of the standard voltage.

[0141] When the voltage temporarily drops to an effective value of 150V, the compensation result is shown in Figure 10: THD = 1.84%, which shows that the compensation effect of the present invention is good. Compared with the prior art, the present invention also has the ability to compensate voltage when the power supply voltage drops slightly to 68.2% of the standard voltage.

[0142] When the voltage drops to an effective value of 110V, the compensation result is shown in FIG11: THD = 2.39%, which shows that the compensation effect of the present invention is good. The compensation limit of the prior art, the present invention also has the voltage compensation capability when the power supply voltage drops moderately to 50% of the standard voltage.

[0143] When the voltage temporarily drops to an effective value of 80V, the compensation effect is shown in Figure 12: THD = 1.38%, which shows that the compensation effect of the present invention is good. It exceeds the compensation limit of the prior art. When the power supply voltage drops deeply to 36.4% of the standard voltage, the present invention still has the ability to compensate the voltage.

[0144] The simulation results show that the invented single-phase uncoupled transformer split source deep compensation series active voltage quality regulator has a good effect on voltage sag depth compensation. When the voltage drops slightly and moderately, the present invention and the prior art can both achieve voltage compensation. However, when the power supply voltage drops deeply, the present invention still has the ability to compensate for the voltage. Compared with the prior art, the present invention has a wider voltage compensation range and at the same time controls the cost.

Claims

1. A single-phase non-coupling transformer split source deep compensation series active voltage quality conditioner, characterized in that: It includes a rectifier unit, an inverter unit, a filter unit and a bypass unit, and is used to achieve deep compensation of AC voltage; wherein: The rectifier unit includes a rectifier VZ, a decoupling transformer T1 and an energy storage capacitor C1 connected in series in sequence; the rectifier VZ converts AC power into DC power, and the electric energy is temporarily stored in the energy storage capacitor C1; when the grid has a voltage quality problem, the grid voltage charges the energy storage capacitor C1 through the decoupling transformer T1 and the rectifier VZ, providing energy for AVQR to inject a compensation voltage into the grid; The inverter unit adopts a split source inverter: an inverter full bridge consisting of a boost inductor L1, two parallel diodes D1, D2, four power tubes S1, S2, S3, S4 and a boost capacitor C2 are connected in series in sequence; when it is necessary to inject compensation voltage into the grid, the inverter unit, driven by the hybrid SPWM control signal, inverts the DC voltage on the energy storage capacitor C1 into the required compensation voltage to compensate for the drop of the grid voltage; Filter unit: a low-pass passive filter consisting of a filter inductor L3 and a filter capacitor C3, wherein one end of the filter inductor L3 is connected to the cathode of the diode D1 or the emitter of the power tube S1 and the collector of the power tube S2, and the other end is connected to the filter capacitor C3; the other end of the filter capacitor C3 is connected to the load; Bypass unit: It consists of a contactor KM1 connected after the roadside capacitor and a pair of anti-parallel thyristors KV1 and KV2 in parallel; the bypass unit performs the operation of switching the AVQR on and off; since the bypass unit is responsible for switching the AVQR on and off, the response time of the bypass unit directly determines the AVQR operation switching time.

2. A single-phase non-coupling transformer split source deep compensation series active voltage quality conditioner according to claim 1, characterized in that: In the rectifier unit, the rectifier VZ adopts an uncontrolled rectifier bridge.

3. A single-phase non-coupling transformer split source deep compensation series active voltage quality conditioner according to claim 1, characterized in that: The filtering unit adopts a low-pass passive LC filter; when working, the higher harmonics other than the fundamental frequency will be filtered out by the filtering unit.

4. A single-phase non-coupling transformer split source deep compensation series active voltage quality conditioner according to claim 1, characterized in that: The inverter unit is equivalently divided into a BOOST part and a full-bridge inverter part. The inverter unit is divided into the following four working modes according to the positive half cycle and negative half cycle of the output voltage under the hybrid SPWM modulation of the power tube conduction timing: Mode 1t0~t1 stage: Before t0, the power tubes S1 and S3 are turned on, and the boost inductor L1 is subjected to reverse pressure (V c3 -V c1 ) and discharge linearly; at time t0, the power tube S3 is turned off, the power tube S2 remains turned off, the power tube S1 and the power tube S4 are turned on, and the discharge ends at time t1; In the interval t0 to t1, for the BOOST part, capacitor C1, diode D2 and power tube S4 are connected in series, diode D2 is turned on, and inductor L1 is subjected to forward voltage V c1 And store energy, the inductor current i L1 Linear rise; In the interval t0 to t1, the full-bridge inverter part, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, form an inverter full bridge. The filter inductor current i L2 It flows through power tube S1 and power tube S4, so: Mode 2t1~t2 stage: At time t1, the full-bridge inverter part in the inverter unit, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, form an inverter full-bridge. The power tube S1 is turned off, the power tube S3 remains turned off, and the power tubes S2 and S4 are turned on, until time t2 ends; In the interval of t1 to t2, for the BOOST part, i.e., capacitor C1, diode D1 is connected in series with power tube S2, diode D2 is cut off, the voltage across diode D2 is clamped to zero, diode D1 is turned on, and boost inductor L1 is subjected to forward voltage V C1 , inductor current i L1 Continue to maintain a linear rise; In the interval t1 to t2, the full-bridge inverter part, i.e., the capacitor C2 and the four power tubes S1, S2, S3, and S4, form an inverter full-bridge. The inductor current iL2 of the full-bridge inverter part continues to flow through the power tubes S2 and S4, and the inductor L2 releases energy. Therefore, there is: Mode 3t2~t3 stage: At time t2, the power tubes S2 and S3 in the inverter unit are turned off, and the power tubes S1 and S4 are turned on. The operation ends at time t3, and the operation process is the same as that of the stage t0 to t1. Mode 4t3~t4 stage: At time t3, the power tube S4 in the inverter unit is turned off, and the power tubes S1 and S3 are turned on until time t4. During this period, the boost inductor L1 releases energy to charge the bus capacitor C2. The above process is repeated in the next switching cycle. In the interval of t3 to t4, in the BOOST part, that is, capacitor C1, diode D1, power tube S1 and capacitor C2 are connected in series, diode D2 is cut off, the voltage across diode D2 is clamped to zero, diode D1 is turned on, the inductor current iL1 is freewheeling through power tube S1, and the two ends of inductor L1 are subjected to reverse voltage (V C2 -V C1 ), the inductor current iL1 decreases linearly: In the interval of t3 to t4, the inductor current iL2 of the full-bridge inverter part, i.e., the capacitor C2 and the four power tubes, is continuous-flowed through the power tubes S1 and S3, so:

5. The single-phase non-coupling transformer split source deep compensation series active voltage quality conditioner according to claim 1, characterized in that: The specific method of the inverter unit, under the drive of the hybrid SPWM control signal, inverting the DC voltage on the energy storage capacitor C1 into the required compensation voltage to compensate for the drop of the grid voltage is: The inverter unit boost inductor L1 is charged in the time period of t0 to t3 and discharged in the time period of t3 to t4, and the DC boost duty cycle is: From the relationship between the input voltage and output voltage of the inverter unit BOOST part, we know that the inverter bus voltage is V C2 for: V C2 =V C1 / (1-d dc ) (9) The output voltage of the full-bridge inverter and the bus voltage satisfy the following relationship: in o_pk =M ac In C2 (10) Where Ts is the switching period, V o_pk is the inverter output sinusoidal voltage amplitude, M ac is the SPWM modulation ratio; Therefore, the relationship between the inverter unit output voltage and input voltage is: The boost ratio of the inverter unit is M ac is the SPWM modulation ratio, D dc is the DC boost duty cycle. In order to prevent over-modulation of harmonic distortion, the SPWM modulation ratio M ac Limit the DC boost duty cycle D dc ; Output voltage V out With input voltage V in , compensation voltage between V o_pk The relationship is: V out =V in +V o_pk (12) Output voltage V out With reference standard voltage V ref The same, that is, V out =V ref , that is, the output voltage V out The peak value is 311V; The input voltage Vin is rectified after the rectifier unit to obtain the rectified voltage V C1 , the relationship between the two is: V in =3.9946V C1 (13) After passing through the inverter unit, the compensation voltage V is obtained, that is: After sorting, we can get the input voltage V in With reference standard voltage V ref The relationship between them is as follows: Assume the compensation depth is G, then According to formula (16), the compensation depth G increases with the DC boost duty cycle D dc and SPWM modulation ratio M ac increases with the increase of; due to the SPWM modulation ratio M ac Limit the DC boost duty cycle D dc , let M ac =D dc ,have to: Therefore, G = f(D dc ).

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