CN105450038A - Modular H bridge cascade multi-level power electronic transformer control system - Google Patents

Abstract

The invention discloses a modular H bridge cascade multi-level power electronic transformer control system, comprising a high-voltage rectifier circuit unit composed of a plurality of cascade single-phase H bridge rectifiers, an isolated converter circuit unit composed of a plurality of parallel high-frequency DC/DC isolated converters correspondingly connected with the single-phase H bridge rectifiers, a low-voltage inverter circuit unit connected to the output end of the isolated converter circuit unit, as well as a high-voltage side controller, an isolation level controller and a low-voltage inverter controller which are separately used for controlling the above units, wherein the controllers independently control the high-voltage rectifier circuit unit, each high-frequency DC/DC isolated converter and the low-voltage inverter circuit unit by adopting a high-voltage rectifier control module, an isolated double-loop control module and a double-loop inverter control module separately. The system simplifies the design of the controllers, and the stability and the reliability of the transformer control system are improved.

Description

Modularization H bridge cascade connection multi-level electric power electric transformer control system

Technical field

The present invention relates to electric and electronic technical field, be specifically related to a kind of converters system.

Background technology

Electric power electric transformer is also called solid-state transformer or flexible transformer, it is the novel transformer based on electric electronic current change technology and electromagnetic induction technology, it changes the system configuration of traditional transformer thoroughly, on the basis realizing the basic functions such as conventional electric power transformer voltage grade transformation, electrical isolation and energy transferring, can also realize many additional functionalities such as bi-directional current control, utility power quality control, be the critical equipment that intelligent grid of future generation is built.Current electric power electric transformer has various topological structures, and generally comprise hiigh pressure stage, isolation level and low-pressure stage three parts, wherein hiigh pressure stage generally adopts the structure of cascade connection multi-level, and isolation level generally adopts the structure of multiple DC/DC wired in parallel.But its controller architecture of these electric power electric transformers is complicated at present, do not possess the ability of three-phase electric energy automatic mutual at different levels balance, and dynamic response performance is undesirable, the fault traversing that simultaneously can not meet when grid-connected asymmetrical voltage falls controls.

Summary of the invention

For solving the problem, the present invention proposes a kind of modularization H bridge cascade connection multi-level electric power electric transformer control system, and this system simplifies Controller gain variations, improves stability and the reliability of voltage transformer system.

The scheme that the present invention solves the problems of the technologies described above is as follows:

Modularization H bridge cascade connection multi-level electric power electric transformer control system, comprise: the hiigh pressure stage rectification circuit unit that the multiple single-phase H bridge rectifier stage joint group being connected to input net side becomes, the isolation level inverter unit that the multiple high frequency DC/DC isolated converters that connect corresponding to single-phase H bridge rectifier quantity compose in parallel, be connected to the low pressure inverter circuit unit of isolation level inverter unit output, and be respectively used to control hiigh pressure stage rectification circuit unit, the high-pressure side controller of isolation level inverter unit and low pressure inverter circuit unit, isolation level controller and low-pressure stage inverter controller, it is characterized in that, high-pressure side controller adopts hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit, isolation level controller adopts output and the power-balance of each high frequency of isolation level double-loop control module controls DC/DC isolated converter, low-pressure stage inverter controller adopts dicyclo inversion control module controls low pressure inverter circuit unit to export low pressure power frequency ac voltage.

Wherein, the method for described hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit is a kind of double loop control, and rate-determining steps is as follows:

2.1) outer voltage controls, the commutating voltage value of receipts or other documents in duplicate phase H bridge rectifier at different levels in each net of input mutually side is gathered respectively by high-pressure side controller, and sue for peace, obtain each phase direct voltage, with each phase direct voltage for value of feedback, after comparing with each phase reference voltage level, calculate three-phase grid value and power reference through proportional integral, input to current inner loop;

2.2) current inner loop controls, grid-connected voltage and the grid-connected current that three-phase inputs net side is gathered respectively by high-pressure side controller, then undertaken after coordinate transform is separated with positive-negative sequence by dual rotary coordinate system phase-locked loop, obtain the positive-negative sequence component of grid phase and grid-connected voltage, carry out after coordinate transform is separated with positive-negative sequence according to grid phase to grid-connected current again, obtain the positive-negative sequence component of grid-connected current, the positive-negative sequence reference value of grid-connected current is calculated according to the positive-negative sequence component of grid-connected value and power reference and grid-connected voltage, then the positive-negative sequence reference value of grid-connected current is compared with the positive-negative sequence component of grid-connected current with proportional integral after, calculate to obtain the modulation voltage reference signal under rotating coordinate system, carried out inverse transformation again, addition obtains the three-phase voltage modulation signal under rest frame,

2.3) modulation module in the controller of high-pressure side generates commutating pulse according to the three-phase voltage modulation signal under rest frame.

Wherein, described isolation level controller adopts the step of each high frequency of isolation level double-loop control module controls DC/DC isolated converter as follows:

3.1) outer shroud controls, isolation level controller gathers busbar voltage and the bus current of high frequency DC/DC isolated converter output, the transform power of each high frequency DC/DC isolated converter is calculated according to busbar voltage and bus current, simultaneously, after busbar voltage is compared with reference busbar voltage, calculate isolated variable power through proportional integral, to figure to obtain the transform power average reference value of each high frequency DC/DC isolated converter then according to high frequency DC/DC isolated converter;

3.2) inner loop power phase shifting control, the transform power average reference value of the transform power of each high frequency DC/DC isolated converter and each high frequency DC/DC isolated converter is compared, then obtain through proportional integral the phase shifting angle controlling each high frequency DC/DC isolated converter, the phase shift modulation module in isolation level controller generates phase-shift pulse according to the phase shifting angle obtained.

Wherein, the step of described dicyclo inversion control module controls low pressure inverter circuit unit is as follows:

4.1) filtering voltage outer shroud controls, low-pressure stage inverter controller gathers inverting output terminal capacitance terminal voltage and is carried out coordinate transform, obtain the capacitance terminal voltage under rotating coordinate system, and it can be used as value of feedback, compare with inverter output voltage reference value, then calculate through proportional integral, obtain inductive current reference value, input to inductive current inner ring;

4.2) inductive current inner ring controls, low-pressure stage inverter controller gathers the inductive current of low pressure inverter circuit unit, and by it compared with inductive current reference value, comparison value is calculated through proportional integral, after then result of calculation being added with inductive current decoupling zero value and capacitance terminal voltage, obtains inversion modulation voltage;

4.3) the inversion pulse modulation module in low-pressure stage inverter controller generates inversion pulse according to inversion modulation voltage.

Compared to prior art, beneficial effect of the present invention is:

A) because the present invention adopts three independently controllers: high-pressure side controller, isolation level controller and low-pressure stage inverter controller carry out independent control to hiigh pressure stage rectification circuit unit, isolation level inverter unit and low pressure inverter circuit unit respectively, greatly reduce the complexity of each Controller gain variations;

B) because each independent control all uses double-loop control mode, dynamic response performance is good, and regulating time and overshoot all greatly reduce;

C) double loop control that hiigh pressure stage rectify control module adopts controls hiigh pressure stage rectification circuit unit under dual rotary coordinate system, can when line voltage is asymmetric fall grid-connected power is controlled, be conducive to carrying out fault traversing control when electric network fault;

D) Double-loop Control Strategy of isolation level double-loop control module employing busbar voltage outer shroud, power inner ring controls each high frequency DC/DC isolated converter, achieves the power equalization between each module while synchronous each module output voltage.

Accompanying drawing explanation

Fig. 1 is the system architecture diagram of modularization H bridge cascade connection multi-level electric power electric transformer control system in the embodiment of the present invention;

Fig. 2 is the hardware topology figure of single hiigh pressure stage rectification circuit and isolation level translation circuit;

Fig. 3 is the hardware topology figure of low pressure inverter circuit unit;

Fig. 4 is hiigh pressure stage rectification control system block diagram;

Fig. 5 is isolation level Double Loop Control System block diagram;

Fig. 6 is low-pressure stage inverse control system block diagram;

Fig. 7 ~ Fig. 8 is respectively C phase line voltage and occurs 50% when falling, A phase reference voltage level waveform, the actual output capacitance voltage waveform of each single-phase H bridge rectifier

Fig. 9 is the busbar voltage waveform of high frequency DC/DC isolated converter output;

Figure 10 is low pressure inverter circuit load voltage, current waveform figure.

Embodiment

Example 1

Below in conjunction with accompanying drawing, concrete introduction is carried out to the present invention:

As shown in Figure 1, the modularization H bridge cascade connection multi-level electric power electric transformer control system that this example provides, its system configuration comprises: the hiigh pressure stage rectification circuit unit that the multiple single-phase H bridge rectifier stage joint group being connected to three-phase input electrical network becomes, the isolation level inverter unit that the multiple high frequency DC/DC isolated converters that connect corresponding to single-phase H bridge rectifier quantity compose in parallel, wherein the hardware topology figure of single hiigh pressure stage rectification circuit and isolation level translation circuit as shown in Figure 2, be connected to the low pressure inverter circuit unit of isolation level inverter unit output, its hardware topology figure as shown in Figure 3, and be respectively used to control hiigh pressure stage rectification circuit unit, the high-pressure side controller of isolation level inverter unit and low pressure inverter circuit unit, isolation level controller and low-pressure stage inverter controller.Wherein, high-pressure side controller adopts hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit; Isolation level controller adopts output and the power-balance of each high frequency of isolation level double-loop control module controls DC/DC isolated converter; Low-pressure stage inverter controller adopts dicyclo inversion control module controls low pressure inverter circuit unit to export low pressure power frequency ac voltage.In this example, the single-phase H bridge rectifier of cascade and the quantity of high frequency DC/DC isolated converter are 15.

See Fig. 4, the method for described hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit is a kind of double loop control, and rate-determining steps is as follows:

2.1) outer voltage controls, and is gathered the rectifier output voltage value of receipts or other documents in duplicate phase H bridge rectifier at different levels in each net of input mutually side respectively, and sues for peace, obtain each phase direct voltage u by high-pressure side controller _ch, with each phase direct voltage u _chfor value of feedback, with each phase reference voltage level relatively, calculate three-phase grid value and power reference P through proportional integral ^*, input to current inner loop;

2.2) current inner loop controls, and gathers by high-pressure side controller the grid-connected voltage u that three-phase inputs net side respectively _abcwith grid-connected current I _abc, then undertaken after coordinate transform is separated with positive-negative sequence, obtaining the positive-negative sequence component of grid phase and grid-connected voltage by dual rotary coordinate system phase-locked loop with again according to grid phase to grid-connected current I _abccarry out after coordinate transform is separated with positive-negative sequence, obtaining the positive-negative sequence component of grid-connected current with according to grid-connected value and power reference P ^*with the positive-negative sequence component of grid-connected voltage calculate the positive-negative sequence reference value of grid-connected current with then by following formula I) the positive-negative sequence reference value of grid-connected current compared with the positive-negative sequence component of grid-connected current with proportional integral after, calculate to obtain the modulation voltage reference signal under rotating coordinate system with

$\left\{\begin{array}{c}{u}_{dref}^P=(i_{Ld}^{P*}-i_{Ld}^P)(K_{iP}+\frac{K_{iI}}{s})-{\mathrm{\ωL}}_s{i}_{Lq}^P+u_d^P\\ u_{qref}^P=(i_{Lq}^{P*}-i_{Lq}^P)(K_{iP}+\frac{K_{iI}}{s})+{\mathrm{\ωL}}_s{i}_{Ld}^P+u_q^P\end{array}\right.---I),$

$\left\{\begin{array}{c}{u}_{dref}^N=(i_{Ld}^{N*}-i_{Ld}^N)(K_{iP}+\frac{K_{iI}}{s})-{\mathrm{\ωL}}_s{i}_{Lq}^N+u_d^N\\ u_{qref}^N=(i_{Lq}^{N*}-i_{Lq}^N)(K_{iP}+\frac{K_{iI}}{s})+{\mathrm{\ωL}}_s{i}_{Ld}^N+u_q^N\end{array}\right.$

Formula I) middle K _iPand K _iIbe respectively proportionality coefficient and integral coefficient, L _sfor input filter inductance value, with the modulation reference signals that forward-order current ring exports, with it is the modulation reference signals that negative-sequence current ring exports.

Then, then by the modulation voltage reference signal inverse transformation under rotating coordinate system and by Formula Il) be added the three-phase voltage modulation signal obtained under rest frame with

$\left\{\begin{array}{c}{u}_{Aref}=u_{Aref}^P+u_{Aref}^N\\ u_{Bref}=u_{Bref}^P+u_{Bref}^N\\ u_{Cref}=u_{Cref}^P+u_{Cref}^N\end{array}\right.---II)$

2.3) the three-phase voltage modulation signal under rest frame is carried out Staircase wave and generates the commutating pulse being used for controlling each H bridge rectifier by the modulation module in the controller of high-pressure side.

See Fig. 5, described isolation level controller adopts the step of each high frequency of isolation level double-loop control module controls DC/DC isolated converter as follows:

3.1) outer shroud controls, and isolation level controller gathers the busbar voltage u of high frequency DC/DC isolated converter output _cLwith bus current i _cL, to be multiplied with bus current according to busbar voltage and to calculate the transform power P of each high frequency DC/DC isolated converter _l, meanwhile, by busbar voltage u _cLwith reference busbar voltage relatively, calculate isolated variable power through proportional integral then by isolated variable power the transform power average reference value P of each high frequency DC/DC isolated converter is figured to obtain divided by high frequency DC/DC isolated converter _lref;

3.2) inner loop power phase shifting control, by the transform power P of each high frequency DC/DC isolated converter _lwith the transform power average reference value P of each high frequency DC/DC isolated converter _lrefcompare, then press formula III) comparison value is carried out the phase shifting angle that proportional integral obtains controlling each high frequency DC/DC isolated converter

Formula III) in, with be respectively proportionality coefficient and integral coefficient,

Then, the phase shift modulation module in isolation level controller generates phase-shift pulse according to the phase shifting angle obtained.

See Fig. 6, the step of described dicyclo inversion control module controls low pressure inverter circuit unit is as follows:

4.1) filtering voltage outer shroud controls, and low-pressure stage inverter controller gathers inverting output terminal capacitance terminal voltage and carried out coordinate transform, obtains the capacitance terminal voltage u under rotating coordinate system _cdand u _cq, and it can be used as value of feedback, by following formula IV) and inverter output voltage reference value with relatively, then calculate through proportional integral, obtain inductive current reference value with

$\left\{\begin{array}{c}{i}_{Lfd}^{*}=(u_{Cd}^{*}-u_{Cd})(K_{vP}+\frac{K_{vI}}{s})-{\mathrm{\ωCu}}_{Cq}\\ i_{Lfd}^{*}=(u_{Cq}^{*}-u_{Cq})(K_{vP}+\frac{K_{vI}}{s})+{\mathrm{\ωCu}}_{Cd}\end{array}\right.---IV)$

Formula IV) in, K _{ν P}and K _{ν I}be respectively proportionality coefficient and integral coefficient, then by inductive current reference value with input to inductive current inner ring;

4.2) inductive current inner ring controls, and low-pressure stage inverter controller gathers the inductive current i of low pressure inverter circuit unit _lfdand i _lfq, and by its with press following formula V) compared with inductive current reference value, comparison value is calculated through proportional integral, after then result of calculation being added with inductive current decoupling zero value and capacitance terminal voltage, obtains inversion modulation voltage:

$\left\{\begin{array}{c}{V}_{ref}=(i_{Ld}^{*}-i_{Ld})(K_{cP}+\frac{K_{cI}}{s})-{\mathrm{\ωL}}_f{i}_{Lfq}+u_{Cd}\\ V_{qref}=(i_{Lq}^{*}-i_{Lq})(K_{cP}+\frac{K_{cI}}{s})+{\mathrm{\ωL}}_f{i}_{Lfd}+u_{Cq}\end{array}\right.---V)$

Formula IV) in, K _cPand K _cIbe respectively proportionality coefficient and integral coefficient,

4.3) the inversion pulse modulation module in low-pressure stage inverter controller generates inversion SPWM pulse according to inversion modulation voltage.

Example 2

For verifying the performance of control system mesohigh level rectification circuit unit provided by the present invention, this example is stablized in A phase voltage and the input of B phase voltage, under there is 50% condition fallen when 0.2s in C phase voltage, system described in example 1 is controlled, wherein, in A phase reference voltage level waveform, A phase the actual output capacitance voltage waveform of each single-phase H bridge rectifier respectively as shown in Fig. 7 ~ Fig. 8:

Be worth for given 12kV after 10kV, 0.2s before 0.2s see Fig. 7, A phase reference voltage level, can find out that each phase direct voltage can track reference value well by waveform;

After 0.2s precontract is 630V, 0.2s, be about 800V see single-phase H bridge rectifier actual value each in Fig. 8, A phase, visible each single-phase H bridge rectifier has good harmony.

Example 3

For verifying the performance of isolation level inverter unit in control system provided by the present invention, system is under isolation level conversion output is set in 800V condition, system is controlled, the busbar voltage waveform of its high frequency DC/DC isolated converter output is as shown in Figure 9: the busbar voltage of high frequency DC/DC isolated converter output is stabilized in 700V before 0.2s, be stabilized in 800V after 0.2s, the busbar voltage of visible output can track reference value rapidly.

Example 4

With low pressure inverter circuit load voltage, current waveform

For verifying the performance of control system mesolow inverter circuit unit provided by the present invention, when default is initial, load is 30kW, load is increased to 60kW by 0.2s, and with this understanding system is controlled, its low pressure inverter circuit load voltage, current waveform as shown in Figure 10: as can be seen from waveform, when 0.2s, load is suddenlyd change to 60kW by 30kW, its output voltage has almost no change, and electric current is changed to about 200A from 100A increase, and visible system output voltage waveforms is very stable.

Claims (4)

1. modularization H bridge cascade connection multi-level electric power electric transformer control system, comprise: the hiigh pressure stage rectification circuit unit that the multiple single-phase H bridge rectifier stage joint group being connected to three-phase input net side becomes, the isolation level inverter unit that the multiple high frequency DC/DC isolated converters that connect corresponding to single-phase H bridge rectifier quantity compose in parallel, be connected to the low pressure inverter circuit unit of isolation level inverter unit output, and be respectively used to control hiigh pressure stage rectification circuit unit, the high-pressure side controller of isolation level inverter unit and low pressure inverter circuit unit, isolation level controller and low-pressure stage inverter controller, it is characterized in that, high-pressure side controller adopts hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit, isolation level controller adopts output and the power-balance of each high frequency of isolation level double-loop control module controls DC/DC isolated converter, low-pressure stage inverter controller adopts dicyclo inversion control module controls low pressure inverter circuit unit to export low pressure power frequency ac voltage.

2. modularization H bridge cascade connection multi-level electric power electric transformer control system as claimed in claim 1, it is characterized in that, the method for described hiigh pressure stage rectify control module controls hiigh pressure stage rectification circuit unit is a kind of double loop control, and rate-determining steps is as follows:

2.1) outer voltage controls, the commutating voltage value of receipts or other documents in duplicate phase H bridge rectifier at different levels in each net of input mutually side is gathered respectively by high-pressure side controller, and sue for peace, obtain each phase direct voltage, with each phase direct voltage for value of feedback, after comparing with each phase reference voltage level, calculate three-phase grid value and power reference through proportional integral, input to current inner loop;

2.2) current inner loop controls, grid-connected voltage and the grid-connected current that three-phase inputs net side is gathered respectively by high-pressure side controller, then undertaken after coordinate transform is separated with positive-negative sequence by dual rotary coordinate system phase-locked loop, obtain the positive-negative sequence component of grid phase and grid-connected voltage, carry out after coordinate transform is separated with positive-negative sequence according to grid phase to grid-connected current again, obtain the positive-negative sequence component of grid-connected current, the positive-negative sequence reference value of grid-connected current is calculated according to the positive-negative sequence component of grid-connected value and power reference and grid-connected voltage, then the positive-negative sequence reference value of grid-connected current is compared with the positive-negative sequence component of grid-connected current with proportional integral after, calculate to obtain the modulation voltage reference signal under rotating coordinate system, carried out inverse transformation again, addition obtains the three-phase voltage modulation signal under rest frame,

2.3) modulation module in the controller of high-pressure side generates commutating pulse according to the three-phase voltage modulation signal under rest frame.

3. modularization H bridge cascade connection multi-level electric power electric transformer control system as claimed in claim 1, is characterized in that, described isolation level controller adopts the step of each high frequency of isolation level double-loop control module controls DC/DC isolated converter as follows:

3.1) outer shroud controls, isolation level controller gathers busbar voltage and the bus current of high frequency DC/DC isolated converter output, the transform power of each high frequency DC/DC isolated converter is calculated according to busbar voltage and bus current, simultaneously, after busbar voltage is compared with reference busbar voltage, calculate isolated variable power through proportional integral, to figure to obtain the transform power average reference value of each high frequency DC/DC isolated converter then according to high frequency DC/DC isolated converter;

3.2) inner loop power phase shifting control, the transform power average reference value of the transform power of each high frequency DC/DC isolated converter and each high frequency DC/DC isolated converter is compared, then obtain through proportional integral the phase shifting angle controlling each high frequency DC/DC isolated converter, the phase shift modulation module in isolation level controller generates phase-shift pulse according to the phase shifting angle obtained.

4. modularization H bridge cascade connection multi-level electric power electric transformer control system as claimed in claim 1, it is characterized in that, the step of described dicyclo inversion control module controls low pressure inverter circuit unit is as follows:

4.1) filtering voltage outer shroud controls, low-pressure stage inverter controller gathers inverting output terminal capacitance terminal voltage and is carried out coordinate transform, obtain the capacitance terminal voltage under rotating coordinate system, and it can be used as value of feedback, compare with inverter output voltage reference value, then calculate through proportional integral, obtain inductive current reference value, input to inductive current inner ring;

4.2) inductive current inner ring controls, low-pressure stage inverter controller gathers the inductive current of low pressure inverter circuit unit, and by it compared with inductive current reference value, comparison value is calculated through proportional integral, after then result of calculation being added with inductive current decoupling zero value and capacitance terminal voltage, obtains inversion modulation voltage;

4.3) the inversion pulse modulation module in low-pressure stage inverter controller generates inversion pulse according to inversion modulation voltage.