CN103997043A - Uniform electricity quality regulator based on T-type three-level inverter and regulating method thereof - Google Patents

Abstract

The invention discloses a uniform electricity quality regulator based on a T-type three-level inverter. The uniform electricity quality regulator based on the T-type three-level inversion technology and a control method of the uniform electricity quality regulator resolve the problem about the electricity quality of a micro power grid. A source and load detection device is used for detecting the real-time conditions of a power source and a load of the micro power grid; a serial-connecting inverter is used for being connected between the power source and the load in series; a parallel-connecting inverter is used for being connected on the load side in parallel; a direct current side energy-storing unit is used for storing energy; a Hall sensor is used for measuring the current and voltage information output by the inverters; an analog acquisition unit converts analog signals into a digital quantity through an external AD in a concentrating mode; a main digital controller is used for achieving the functions of operating state judgment, data analysis and the like; and a driving circuit is used for achieving output of PWM signals and protection over fault hardware. According to a control strategy of a T-type three-level inverter UPQC, a modified quasi proportional resonant current control strategy and a neutral-point voltage balance control strategy of PWM pulse optimizing switchover are provided.

Description

A kind of Research on Unified Power Quality Conditioner and control method thereof based on T-shaped three level

Technical field

Research on Unified Power Quality Conditioner, i.e. UPQC, it is a kind of comprehensive compensating device that possesses the most of power quality problems of effective solution.The present invention relates to a kind of micro-electrical network Research on Unified Power Quality Conditioner and control method based on T-shaped three Level Technology, belong to intelligent grid field.

Background technology

Micro-electrical network is a kind of system being jointly comprised of micro-generators and loads, and its power quality problem is analyzed as follows: in micro-electrical network, except load variations impact, micro-output power of power supply fluctuation also can be drawn voltage flicker; In addition, nonlinear-load will produce a large amount of harmonic waves, cause the imbalance of electrical network three-phase voltage; Meanwhile, micro-power supply and various converters also can produce certain harmonic wave, affect the normal operation of micro-electrical network.

For the above-mentioned comprehensive electric energy quality problem of micro-electrical network, use Passive LC filter, though can reduce harmonic wave, improve the power factor of AC load, application confined condition is more.In addition, use single serial/parallel type Active Power Filter-APF or single dynamic electric voltage recovery device, be all difficult to realize the power quality controlling under various working.

UPQC is a kind of device that can effectively solve the main power quality problem such as micro-electric network voltage flicker, current harmonics: (Fig. 1's) tandem type converter part is by the voltage amount of falling of online detection load side, produce in real time an impact that voltage compensation quantity is offset the amount of falling, make the power supply of load side meet all the time standard, efficiently solve voltage flicker problem; (Fig. 1's) parallel connection type converter partly passes through the online current distortion component that detects micro-mains side, and produces in real time a current compensation amount that amplitude equal phase is contrary, to realize the rectification to power network current distortion.Main circuit topological structure is one of core component of UPQC, what in existing many level-types main circuit topology, be most widely used is diode clamp type tri-level circuit, it realizes mid-point voltage clamper by introducing diode, but voltage balance control becomes complicated.Engineering circles is badly in need of a kind of new and effective circuit topology and is significantly promoted UPQC characteristic and performance, in addition, the performance quality of UPQC is also that real-time detection for harmonic current is with separated, relevant complicated algorithm is had relatively high expectations to system real time, thereby the design of high-speed figure control system is proposed to new demand.

Summary of the invention

In order to solve existing the problems referred to above, the invention provides a kind of Research on Unified Power Quality Conditioner based on T-shaped three level, can the main line voltage of effective compensation fall, fluctuation, overvoltage, voltage distortion, and the comprehensive power supply quality problem that non-linear and uncompensated load brings in micro-electrical network, the present invention is mainly used in micro-electrical network, and micro-electrical network mainly comprises generators and loads.

Technical problem to be solved by this invention is achieved through the following technical solutions:

A kind of Research on Unified Power Quality Conditioner based on T-shaped three level, comprise the power detector for detection of power supply, load detection device, series transformer, parallel connection converter, energy-storage units, Hall element, analog acquisition unit, master control digitizer, and drive circuit, described series transformer is connected with the mains side in micro-electrical network by autotransformer, described parallel connection converter is connected in parallel on the load side in micro-electrical network, described energy-storage units is connected with parallel connection converter with string converter simultaneously, described power detector while and micro-power supply, series transformer and main digitial controller connect, load detection device is connected with load and analog acquisition unit simultaneously, series transformer is also connected drive circuit and Hall element with parallel connection converter simultaneously, analog acquisition unit is connected with main digitial controller and Hall element simultaneously, main digitial controller is also connected with drive circuit.

Preferably, described tandem type converter comprises the first DC bus capacitor dividing potential drop branch road, the first three phase full bridge inverter circuit, the first bidirectional switch pipe, the second bidirectional switch pipe and the 3rd bidirectional switch pipe, and one end of described first, second and third bidirectional switch pipe is all connected to the mid point o of the first DC bus capacitor dividing potential drop branch road ₁, the other end connects respectively the mid point of the three-phase brachium pontis of described the first three phase full bridge inverter circuit, and three brachium pontis mid points of described the first three phase full bridge inverter circuit form the output of series transformer; The output of series transformer is by LC filter circuit, by the autotransformer series connection mains side in electrical network in a subtle way, described parallel connection converter comprises: the second DC bus capacitor dividing potential drop branch road, the second three phase full bridge inverter circuit, the 4th bidirectional switch pipe, the 5th bidirectional switch pipe, the 6th bidirectional switch pipe, one end of described fourth, fifth, six bidirectional switch pipes is all connected to the mid point o of the second capacitance partial pressure branch road ₂the other end connects respectively the mid point of the three-phase brachium pontis of described the second three phase full bridge inverter circuit, three brachium pontis mid points of described the second three phase full bridge inverter circuit form the output of parallel connection converter, and this output is by LC filter circuit, and parallel connection accesses the load side in micro-electrical network.

Preferably, described the first DC side dividing potential drop branch road comprises capacitor C ₁, capacitor C ₂, the first three phase full bridge inverter circuit comprises switching tube S _a13, switching tube S _b13, switching tube S _c13, switching tube S _a14, switching tube S _b14, switching tube S _c14, the first bidirectional switch pipe comprises switching tube S _a11, switching tube S _a12, the second bidirectional switch pipe comprises switching tube S _b11, switching tube S _b12, the 3rd bidirectional switch pipe comprises switching tube S _c11, switching tube S _c12; Described the second DC bus capacitor dividing potential drop branch road comprises capacitor C ₃, capacitor C ₄, the second three phase full bridge inverter circuit comprises switching tube S _a23, switching tube S _b23, switching tube S _c23, switching tube S _a24, switching tube S _b24, switching tube S _c24, the 4th bidirectional switch pipe comprises switching tube S _a21, switching tube S _a22, the 5th bidirectional switch pipe comprises switching tube S _b21, switching tube S _b22, the 6th bidirectional switch pipe comprises switching tube S _c21, S _c22.

Preferably, described main digitial controller also comprises for improving the accurate ratio resonant controller of series and parallel converter output waveform quality and stability.

A quality of power supply control method for Research on Unified Power Quality Conditioner based on T-shaped three level, is characterized in that: described quality of power supply control method comprises harmonic current control method and voltage flicker compensation method, wherein:

Described harmonic current control method comprises: main digitial controller detects the magnitude of current at U1, V1, W1 place in real time, and the digital quantity of three-phase current is forwarded under d, q synchronous coordinate system by 3/2 coordinate transform.Wherein, fundametal compoment is characterized by direct current signal under d axle, and harmonic component is characterized by AC signal.Adopt wave digital lowpass filter filtering AC signal, leave the DC quantity that characterizes fundametal compoment, and this direct current signal is poor with the original of ac that U1, V1, W1 place are detected after 3/2 coordinate inverse transformation, obtain the distortion current reference instruction of auto levelizer compensation use, accurate ratio resonant controller is by its Current Control Strategy real-time tracking and control current compensation effect; Meanwhile, in real time Detection capacitance C3, C4 DC voltage difference, and carry out upper and lower pressure reduction adjusting, then result is superimposed to and in compensate component, carries out integrated treatment, and produce pwm pulse signal.This pulse signal is according to the A that optimizes order driving parallel connection type converter ₂phase switching tube S _a21, S _a22, S _a23, S _a24, B ₂phase switching tube S _b21, S _b22, S _b23, S _b24, D ₂phase switching tube S _c21, S _c22, S _c23, S _c24thereby, by capacitor C ₃, C ₄direct current convert the AC signal outlet side with harmonic component equal and opposite in direction single spin-echo to, then by net side filter inductance L _a2, L _b2, L _c2and capacitor C _u2, C _v2, C _w2the filter circuit forming injects electrical network after processing, and finally guarantees that power network current waveform meets good sinusoidal degree demand, wherein switching tube S _a21with S _a23, S _a22with S _a24, S _b21with S _b23, S _b22with S _b24, S _c21with S _c23, S _c22with S _c24the situation that turns on and off be complementary relationship.

Described voltage flicker compensation method comprises: main digitial controller detects voltage magnitude and the phase information at U2, V2, W2 place in real time, by positive/negative order coordinate transform and filtering, process computing, allocation of distortion while extracting voltage flicker, and then draw corresponding compensation rate, through pwm pulse, optimize the space vector PWM driving pulse that module produces a graded again, this pwm pulse signal carries out controlling after power amplification the A of series transformer by drive circuit unit ₁phase switching tube S _a11, S _a12, S _a13, S _a14, B ₁phase switching tube S _b11, S _b12, S _b13, S _b14, D ₁phase switching tube S _c11, S _c12, S _c13, S _c14turn on and off, thereby will be stored in capacitor C ₁, C ₂direct current be transformed into the three-phase alternating current component can bucking voltage falling.This output component is by net side filter inductance L _a1, L _b1, L _c1and capacitor C _v1, C _u1, C _w1after the filter circuit shaping forming, by coupling transformer T _u1, T _v1, T _w1line attachment, falls value with the voltage of real-Time Compensation load side U2, V2, W2.Wherein, S _a11with S _a13, S _a12with S _a14, S _b11with S _b13, S _b12with S _b14, S _c11with S _c13, S _c12with S _c14the situation that turns on and off be complementary relationship.

Further, the Current Control Strategy of described accurate ratio resonant controller comprises the following steps:

A, direct voltage U _dafter T-shaped tri-level inversion, filtered to voltage V by LC _o;

B, from V _oto V _itransfer function be: wherein l is filtering inductance, and C is filter capacitance, and R is load resistance, ω _nfor natural frequency, δ is error rate, V _ofor input voltage; V _ifor output voltage; S is the Laplace transformation of time t;

C, the Current Control based on accurate ratio resonant controller, its transfer function is, wherein, K _p, K _ibe respectively proportionality coefficient and integral coefficient, ω ₀for resonance frequency, ω _cfor cut-off frequency, s is the Laplace transformation of time t;

D, the control strategy based on filter capacitor current feedback, the open-loop transfer function based on capacitor current feedback is: $G_{\mathrm{kc}}\left(s\right)=\frac{K_v(K_p+\frac{{2K}_i{\mathrm{\ω}}_{c}s}{{\mathrm{\ω}}_0^2+2{\mathrm{\ω}}_{c}s+s^2})}{\frac{1}{K_{\mathrm{svpwm}}}+(K_{i}C+\frac{L}{K_{\mathrm{svpwm}}R})s+\frac{\mathrm{LC}}{K_{\mathrm{svpwm}}}{s}^2},$ Wherein L is filtering inductance, and C is filter capacitance; R is load resistance, K _vfor Voltage Feedback coefficient, K _ifor current feedback coefficient, K _svpwmfor proportionality coefficient.

The beneficial effect that the present invention reaches is:

1. adopt T-shaped three Level Technology, major loop switching tube bears half of DC voltage, is U _d/ 2, power device voltage stress is little; Meanwhile, the increase of level number, makes the more approaching sine of waveform, and harmonic content is low.

2. the series transformer of Research on Unified Power Quality Conditioner and parallel connection converter adopt T-shaped three level of three-phase as main circuit, and its conduction loss is lower, and with diode clamp three level topologys, number of devices is further reduced.

3. the Current Control based on accurate ratio resonant controller, effectively improves converter output waveform quality and stability.

Accompanying drawing explanation

Fig. 1 is general structure of the present invention and annexation schematic diagram;

Fig. 2 is the circuit diagram of parallel connection converter of the present invention and series transformer;

Fig. 3 is unidirectional T-shaped tri-level circuit schematic diagram;

Fig. 4 is the transfer function block diagram of the accurate ratio resonant controller of modified model.

Embodiment

In order to further describe technical characterstic of the present invention and effect, below in conjunction with the drawings and specific embodiments, the present invention is described further.

As shown in 1, a kind of micro-electrical network Research on Unified Power Quality Conditioner based on T-shaped three Level Technology, comprise the power detector 1a for detection of power supply, load detection device 1b, tandem type converter 2, parallel connection type converter 3, energy-storage units 4, Hall element 5, analog acquisition unit 6, master control digitizer 7, and drive circuit 8, described series transformer 2 three-phases are lived circuit and by autotransformer, are concatenated in electrical network after LC filter circuit, described parallel connection converter 3 is by LC filter circuit access in parallel electrical network, described energy-storage units 4 is connected with parallel connection converter 3 with string converter 2 simultaneously, described power detector 1a while and micro-power supply, series transformer 1a and main digitial controller 7 connect, load detection device 1b is connected with load and analog acquisition unit 6 simultaneously, series transformer 2 is also connected drive circuit 8 and Hall element 5 with parallel connection converter 3 simultaneously, analog acquisition unit 6 is connected with main digitial controller 7 and Hall element 5 simultaneously, main digitial controller 7 is also connected with drive circuit 8, described power detector 1a and load detection device 1b are for detection of the real-time condition of power supply and the load of micro-electrical network, series transformer 2 provides highly reliable power supply for sensitive loads, effectively solve the problem of voltage dip, the harmonic current distortion problem that parallel connection converter 3 causes for solving load, described string, parallel connection converter all adopts T-shaped three Level Technology of three-phase, energy-storage units 4 is for string, the stored energy of parallel connection converter, Hall element 5 is for measurement translator output current information of voltage, digitial controller 7 is passed to after converting the voltage collecting and current analog signal to digital quantity by AD converter again in described analog acquisition unit 6, after 7 pairs of data memory calculation process of main digitial controller, by pwm pulse optimized algorithm, produce pwm signal, and amplify and drive afterwards string through overdrive circuit 8, parallel connection converter, described main digitial controller is for the judgement of finishing device running status, data analysis, incident management, compensation policy is realized, software protection etc., main digitial controller is also provided with the accurate ratio resonant controller of modified model, it mainly improves string by Current Control Strategy, parallel connection converter output voltage wave quality and stability.

(wherein Fig. 2 adopts the parallel connection converter of T-shaped three Level Technology and the circuit diagram of series transformer) sees figures.1.and.2

Described tandem type converter 2 comprises the first DC bus capacitor dividing potential drop branch road, the first three phase full bridge inverter circuit, the first bidirectional switch pipe, the second bidirectional switch pipe and the 3rd bidirectional switch pipe, and one end of described first, second and third bidirectional switch pipe is all connected to the mid point o of the first DC bus capacitor dividing potential drop branch road ₁, the other end connects respectively the mid point of the three-phase brachium pontis of described the first three phase full bridge inverter circuit, and three brachium pontis mid points of described the first three phase full bridge inverter circuit form the output of series transformer 2; The output of series transformer 2 is by LC filter circuit, by the autotransformer series connection mains side in electrical network in a subtle way, described parallel connection converter 3 comprises: the second DC bus capacitor dividing potential drop branch road, the second three phase full bridge inverter circuit, the 4th bidirectional switch pipe, the 5th bidirectional switch pipe, the 6th bidirectional switch pipe, one end of described fourth, fifth, six bidirectional switch pipes is all connected to the mid point o of the second capacitance partial pressure branch road ₂the other end connects respectively the mid point of the three-phase brachium pontis of described the second three phase full bridge inverter circuit, three brachium pontis mid points of described the second three phase full bridge inverter circuit form the output of parallel connection converter 3, this output is by LC filter circuit, load side in the micro-electrical network of access in parallel, described the first DC side dividing potential drop branch road comprises capacitor C ₁, capacitor C ₂, the first three phase full bridge inverter circuit comprises switching tube S _a13, switching tube S _b13, switching tube S _c13, switching tube S _a14, switching tube S _b14, switching tube S _c14, the first bidirectional switch pipe comprises switching tube S _a11, switching tube S _a12, the second bidirectional switch pipe comprises switching tube S _b11, switching tube S _b12, the 3rd bidirectional switch pipe comprises switching tube S _c11, switching tube S _c12; Described the second DC bus capacitor dividing potential drop branch road comprises capacitor C ₃, capacitor C ₄, the second three phase full bridge inverter circuit comprises switching tube S _a23, switching tube S _b23, switching tube S _c23, switching tube S _a24, switching tube S _b24, switching tube S _c24, the 4th bidirectional switch pipe comprises switching tube S _a21, switching tube S _a22, the 5th bidirectional switch pipe comprises switching tube S _b21, switching tube S _b22, the 6th bidirectional switch pipe comprises switching tube S _c21, S _c22.

Described quality of power supply control method comprises harmonic current control method and voltage flicker control method, wherein:

Harmonic current control method comprises: main digitial controller detects the magnitude of current at U1, V1, W1 place in real time, and the digital quantity of three-phase current is forwarded under d, q synchronous coordinate system by 3/2 coordinate transform.Wherein, fundametal compoment is characterized by direct current signal under d axle, and harmonic component is characterized by AC signal.Adopt wave digital lowpass filter filtering AC signal, leave the DC quantity that characterizes fundametal compoment, and this direct current signal is poor with the original of ac that U1, V1, W1 place are detected after 3/2 coordinate inverse transformation, obtain the distortion current reference instruction of auto levelizer compensation use, accurate ratio resonant controller is by its Current Control Strategy real-time tracking and control current compensation effect; Meanwhile, in real time Detection capacitance C3, C4 DC voltage difference, and carry out upper and lower pressure reduction adjusting, then result is superimposed to and in compensate component, carries out integrated treatment, and produce pwm pulse signal.This pulse signal is according to the A that optimizes order driving parallel connection type converter (3) ₂phase switching tube S _a21, S _a22, S _a23, S _a24, B ₂phase switching tube S _b21, S _b22, S _b23, S _b24, D ₂phase switching tube S _c21, S _c22, S _c23, S _c24thereby, by capacitor C ₃, C ₄direct current convert the AC signal outlet side with harmonic component equal and opposite in direction single spin-echo to, then by net side filter inductance L _a2, L _b2, L _c2and capacitor C _u2, C _v2, C _w2the filter circuit forming injects electrical network after processing, and finally guarantees that power network current waveform meets good sinusoidal degree demand, wherein switching tube S _a21with S _a23, S _a22with S _a24, S _b21with S _b23, S _b22with S _b24, S _c21with S _c23, S _c22with S _c24the situation that turns on and off be complementary relationship;

Voltage flicker compensation method comprises: main digitial controller detects voltage magnitude and the phase information at U2, V2, W2 place in real time, by positive/negative order coordinate transform and filtering, process computing, allocation of distortion while extracting voltage flicker, and then draw corresponding compensation rate, through pwm pulse, optimize the space vector PWM driving pulse that module produces a graded again, this pwm pulse signal carries out controlling after power amplification the A of series transformer (2) by drive circuit unit ₁phase switching tube S _a11, S _a12, S _a13, S _a14, B ₁phase switching tube S _b11, S _b12, S _b13, S _b14, D ₁phase switching tube S _c11, S _c12, S _c13, S _c14turn on and off, thereby will be stored in capacitor C ₁, C ₂direct current be transformed into the three-phase alternating current component can bucking voltage falling.This output component is by net side filter inductance L _a1, L _b1, L _c1and capacitor C _v1, C _u1, C _w1after the filter circuit shaping forming, by coupling transformer T _u1, T _v1, T _w1line attachment, falls value with the voltage of real-Time Compensation load side U2, V2, W2.Wherein, S _a11with S _a13, S _a12with S _a14, S _b11with S _b13, S _b12with S _b14, S _c11with S _c13, S _c12with S _c14the situation that turns on and off be complementary relationship.

In order to meet the interference free performance of system and to the high-quality requirement of output voltage waveforms, to the present invention proposes the Current Control Strategy based on accurate ratio resonant controller.Its step is as follows:

Step 1, single-phase T-shaped three level topologys as shown in Figure 3, direct voltage U _dafter T-shaped tri-level inversion, filtered to voltage V by LC _o.

Step 2, from V _oto V _itransfer function be:

$G\left(s\right)=\frac{V_i}{V_o}=\frac{{\mathrm{\ω}}_n^2}{{\mathrm{\ω}}_n^2+2{\mathrm{\δ\ω}}_{n}s+s^2}$

Wherein, l is filtering inductance; C is filter capacitance; R is load resistance; ω _nfor natural frequency; δ is error rate; V _ofor input voltage; V _ifor output voltage; S is the Laplace transformation of time t.

Step 3, the Current Control based on accurate ratio resonant controller, its control block diagram is as shown in Figure 4.

the transfer function of the ratio that is as the criterion resonant controller, wherein, K _p, K _ibe respectively proportionality coefficient and integral coefficient, ω ₀for resonance frequency, ω _cfor cut-off frequency.

Step 4, the control strategy based on filter capacitor current feedback, can proofread and correct inverter output voltage in advance, makes the load characteristic hardening of system.

Open-loop transfer function based on capacitor current feedback system is:

$G_{\mathrm{kc}}\left(s\right)=\frac{K_v(K_p+\frac{{2K}_i{\mathrm{\ω}}_{c}s}{{\mathrm{\ω}}_0^2+2{\mathrm{\ω}}_{c}s+s^2})}{\frac{1}{K_{\mathrm{svpwm}}}+(K_{i}C+\frac{L}{K_{\mathrm{svpwm}}R})s+\frac{\mathrm{LC}}{K_{\mathrm{svpwm}}}{s}^2},$

Wherein, L is filtering inductance; C is filter capacitance; R is load resistance; K _vfor Voltage Feedback coefficient; K _ifor current feedback coefficient; K _svpwmfor proportionality coefficient.

Above-described embodiment does not limit the present invention in any form, all take to be equal to replace or technical scheme that the form of equivalent transformation obtains, within all dropping on protection scope of the present invention.

Claims (6)

1. the Research on Unified Power Quality Conditioner based on T-shaped three level, it is characterized in that: comprise the power detector (1a) for detection of power supply, load detection device (1b), series transformer (2), parallel connection converter (3), energy-storage units (4), Hall element (5), analog acquisition unit (6), master control digitizer (7), and drive circuit (8), described series transformer (2) is connected with the mains side in micro-electrical network by autotransformer, described parallel connection converter (3) is connected in parallel on the load side in micro-electrical network, described energy-storage units (4) is connected with parallel connection converter (3) with string converter (2) simultaneously, described power detector (1a) while and micro-power supply, series transformer (1a) and main digitial controller (7) connect, load detection device (1b) is connected with load and analog acquisition unit (6) simultaneously, series transformer (2) is also connected drive circuit (8) and Hall element (5) with parallel connection converter (3) simultaneously, analog acquisition unit (6) is connected with main digitial controller (7) and Hall element (5) simultaneously, main digitial controller (7) is also connected with drive circuit (8).

2. a kind of Research on Unified Power Quality Conditioner based on T-shaped three level according to claim 1, it is characterized in that: described tandem type converter (2) comprises the first DC bus capacitor dividing potential drop branch road, the first three phase full bridge inverter circuit, the first bidirectional switch pipe, the second bidirectional switch pipe and the 3rd bidirectional switch pipe, and one end of described first, second and third bidirectional switch pipe is all connected to the mid point o of the first DC bus capacitor dividing potential drop branch road ₁, the other end connects respectively the mid point of the three-phase brachium pontis of described the first three phase full bridge inverter circuit, and three brachium pontis mid points of described the first three phase full bridge inverter circuit form the output of series transformer (2); The output of series transformer (2) is by LC filter circuit, by the autotransformer series connection mains side in electrical network in a subtle way, described parallel connection converter (3) comprising: the second DC bus capacitor dividing potential drop branch road, the second three phase full bridge inverter circuit, the 4th bidirectional switch pipe, the 5th bidirectional switch pipe, the 6th bidirectional switch pipe, one end of described fourth, fifth, six bidirectional switch pipes is all connected to the mid point o of the second capacitance partial pressure branch road ₂the other end connects respectively the mid point of the three-phase brachium pontis of described the second three phase full bridge inverter circuit, three brachium pontis mid points of described the second three phase full bridge inverter circuit form the output of parallel connection converter (3), and this output is by LC filter circuit, and parallel connection accesses the load side in micro-electrical network.

3. a kind of Research on Unified Power Quality Conditioner based on T-shaped three level according to claim 2, is characterized in that: described the first DC side dividing potential drop branch road comprises capacitor C ₁, capacitor C ₂, the first three phase full bridge inverter circuit comprises switching tube S _a13, switching tube S _b13, switching tube S _c13, switching tube S _a14, switching tube S _b14, switching tube S _c14, the first bidirectional switch pipe comprises switching tube S _a11, switching tube S _a12, the second bidirectional switch pipe comprises switching tube S _b11, switching tube S _b12, the 3rd bidirectional switch pipe comprises switching tube S _c11, switching tube S _c12; Described the second DC bus capacitor dividing potential drop branch road comprises capacitor C ₃, capacitor C ₄, the second three phase full bridge inverter circuit comprises switching tube S _a23, switching tube S _b23, switching tube S _c23, switching tube S _a24, switching tube S _b24, switching tube S _c24, the 4th bidirectional switch pipe comprises switching tube S _a21, switching tube S _a22, the 5th bidirectional switch pipe comprises switching tube S _b21, switching tube S _b22, the 6th bidirectional switch pipe comprises switching tube S _c21, S _c22.

4. a kind of Research on Unified Power Quality Conditioner based on T-shaped three level according to claim 1, is characterized in that: described main digitial controller (7) also comprises for improving the accurate ratio resonant controller of series and parallel converter output waveform quality and stability.

5. the quality of power supply control method of a kind of Research on Unified Power Quality Conditioner based on T-shaped three level according to claim 1, is characterized in that: described quality of power supply control method comprises harmonic current control method and voltage flicker compensation method, wherein:

Described harmonic current control method comprises: main digitial controller detects the magnitude of current at U1, V1, W1 place in real time, and the digital quantity of three-phase current is forwarded under d, q synchronous coordinate system by 3/2 coordinate transform.Wherein, fundametal compoment is characterized by direct current signal under d axle, and harmonic component is characterized by AC signal.Adopt wave digital lowpass filter filtering AC signal, leave the DC quantity that characterizes fundametal compoment, and this direct current signal is poor with the original of ac that U1, V1, W1 place are detected after 3/2 coordinate inverse transformation, obtain the distortion current reference instruction of auto levelizer compensation use, accurate ratio resonant controller is by its Current Control Strategy real-time tracking and control current compensation effect; Meanwhile, in real time Detection capacitance C3, C4 DC voltage difference, and carry out upper and lower pressure reduction adjusting, then adjusting result is superimposed to and in compensate component, carries out integrated treatment, and produce pwm pulse signal.This pulse signal is according to the A that optimizes order driving parallel connection type converter (3) ₂phase switching tube S _a21, S _a22, S _a23, S _a24, B ₂phase switching tube S _b21, S _b22, S _b23, S _b24, D ₂phase switching tube S _c21, S _c22, S _c23, S _c24thereby, by capacitor C ₃, C ₄direct current convert the AC signal outlet side with harmonic component equal and opposite in direction single spin-echo to, then by net side filter inductance L _a2, L _b2, L _c2and capacitor C _u2, C _v2, C _w2the filter circuit forming injects electrical network after processing, and finally guarantees that power network current waveform meets good sinusoidal degree demand, wherein switching tube S _a21with S _a23, S _a22with S _a24, S _b21with S _b23, S _b22with S _b24, S _c21with S _c23, S _c22with S _c24the situation that turns on and off be complementary relationship;

Described voltage flicker compensation method comprises: main digitial controller detects voltage magnitude and the phase information at U2, V2, W2 place in real time, by positive/negative order coordinate transform and filtering, process computing, allocation of distortion while extracting voltage flicker, and then draw corresponding compensation rate, through pwm pulse, optimize the space vector PWM driving pulse that module produces a graded again, this pwm pulse signal carries out controlling after power amplification the A of series transformer (2) by drive circuit unit ₁phase switching tube S _a11, S _a12, S _a13, S _a14, B ₁phase switching tube S _b11, S _b12, S _b13, S _b14, D ₁phase switching tube S _c11, S _c12, S _c13, S _c14turn on and off, thereby will be stored in capacitor C ₁, C ₂direct current be transformed into the three-phase alternating current component can bucking voltage falling.This output component is by net side filter inductance L _a1, L _b1, L _c1and capacitor C _v1, C _u1, C _w1after the filter circuit shaping forming, by coupling transformer T _u1, T _v1, T _w1line attachment, falls value with the voltage of real-Time Compensation load side U2, V2, W2.Wherein, S _a11with S _a13, S _a12with S _a14, S _b11with S _b13, S _b12with S _b14, S _c11with S _c13, S _c12with S _c14the situation that turns on and off be complementary relationship.

6. the quality of power supply control method of a kind of Research on Unified Power Quality Conditioner based on T-shaped three level according to claim 5, is characterized in that: the Current Control Strategy of described accurate ratio resonant controller comprises the following steps:

A, direct voltage U _dafter T-shaped tri-level inversion, filtered to voltage V by LC _o;

B, from V _oto V _itransfer function be: wherein l is filtering inductance, and C is filter capacitance, and R is load resistance, ω _nfor natural frequency, δ is error rate, V _ofor input voltage; V _ifor output voltage; S is the Laplace transformation of time t;

C, the Current Control based on accurate ratio resonant controller, its transfer function is wherein, K _p, K _ibe respectively proportionality coefficient and integral coefficient, ω ₀for resonance frequency, ω _cfor cut-off frequency, s is the Laplace transformation of time t;

D, the control strategy based on filter capacitor current feedback, the open-loop transfer function based on capacitor current feedback is: $G_{\mathrm{kc}}\left(s\right)=\frac{K_v(K_p+\frac{{2K}_i{\mathrm{\ω}}_{c}s}{{\mathrm{\ω}}_0^2+2{\mathrm{\ω}}_{c}s+s^2})}{\frac{1}{K_{\mathrm{svpwm}}}+(K_{i}C+\frac{L}{K_{\mathrm{svpwm}}R})s+\frac{\mathrm{LC}}{K_{\mathrm{svpwm}}}{s}^2},$ Wherein L is filtering inductance, and C is filter capacitance; R is load resistance, K _vfor Voltage Feedback coefficient, K _ifor current feedback coefficient, K _svpwmfor proportionality coefficient.