CN104578859B - Voltage-sharing controlling method for direct current bus voltage of single-phase power electronic transformer - Google Patents

Abstract

The invention discloses a voltage-sharing controlling method for a direct current bus voltage of a single-phase power electronic transformer. A power main circuit of a single-phase DC-AC power electronic transformer is composed of an isolation level and an inversion level. The isolation level comprises high frequency isolation type DC-DC convertors. The inversion level comprises DC-AC inverters. The input ends of all the DC-DC convertors of the isolation level are in series connection with a medium voltage or high voltage direct current voltage source. The output ends of the DC-DC convertors are connected with the direct current input ends of the corresponding DC-AC inverters of the inversion level. The alternating current sides of all the DC-AC inverters of the inversion level are in series connection with an output filter. The controlling method comprises the following steps: firstly, the voltage-sharing control is carried out on bus voltages of the direct current source side of the power electronic transformer; secondly, the voltage-sharing control is carried out on bus voltages of the output side of the isolation level of the power electronic transformer. According to the controlling method, the voltage-sharing control among cascading modules of the cascading type single-phase power electronic transformer can be achieved, and the method is simple. The correctness and the reliability of the method are verified through simulation results, and a good reference value is provided for the engineering application.

Description

A kind of Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method

Technical field:

The present invention relates to application in power system for the Power Electronic Technique, more particularly, to a kind of Monophase electric power electronic transformer Device DC bus-bar voltage pressure equalizing control method.

Background technology:

Traditional power transformer structure is simple, efficiency high, reliability are high, is widely used in power system.But too low work Working frequency leads to traditional transformer volume big, heavy, and mineral oil, epoxy resin, fire resistant oil etc. are situated between as insulation or cooling There is the potential risk of fire and environmental pollution in the use of matter.In addition, it is typically only capable to enough realize electrical isolation, electric pressure change Change and power bi-directional transmission etc. relative single function, and no the net side quality of power supply adjust, harmonic propagation isolation, overload and fault Protection, load voltage regulation etc. function.These weakness of traditional transformer make it cannot meet some intelligent grids etc. The functional requirement of new opplication occasion.For the above-mentioned weakness of traditional transformer, research worker and engineer propose power electronics Transformator (power electronic transformer) or solid-state transformer (solid-state transformer) add To solve.

In the past few decades, Power Electronic Technique has considerable comprehensive fast development, increasing electric power electricity Sub-device is applied in power system.Then, the electricity of the single tube of business-like power electronic power device or power model at present Pressure grade still can not meet the application of mesohigh rank, generally to be solved using the module-cascade of low-voltage-grade.Due to Have such problems as between cascade module parameter mismatch, loss differ, can make whole cascade system cannot normal work, because This cascade structure needs to realize the Pressure and Control between DC bus-bar voltage by certain control strategy.

Content of the invention:

Present invention aims to there is the unbalanced deficiency of DC bus-bar voltage in existing cascade module, there is provided A kind of Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method.

For reaching above-mentioned purpose, the present invention adopts the following technical scheme that and is achieved:

A kind of Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method, this single-phase dc-ac power electronics becomes The power main circuit of depressor is made up of isolation level and inverse cascade, and wherein, isolation level is high-frequency isolation type dc-dc changer, inversion Level is dc-ac inverter；The input series connection medium-pressure or high pressure direct voltage source of all dc-dc changers of isolation level, defeated Go out the direct-flow input end of the corresponding inverse cascade dc-ac inverter of termination；All dc-ac inverter ac sides of inverse cascade are using series connection Mode connects output filter；This control method comprises the following steps: electric power electric transformer DC source side bus voltage is all voltage-controlled System and electric power electric transformer isolation level export side bus voltage Pressure and Control.

The present invention is further improved by: electric power electric transformer DC source side bus voltage Pressure and Control specifically include Following step of realizing:

Step 1.1, detects each dc-dc changer DC voltage v of electric power electric transformer isolation level input side_{dc_11}、 v_{dc_12}、…、v_{dc_1i}, and obtain meansigma methodss v of this n DC voltage_1aveReference is all pressed using the DC side as in step 1.2 Value, wherein, i=1,2 ..., n；

$v_{1\mathrm{ave}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{\mathrm{dc}\_1i}$

Step 1.2, by each module DC voltage value v in step 1.1 measured_{dc_1i}With obtain in step 1.1 DC voltage meansigma methodss v_1aveCompare, its output obtains each dc-dc changer direct current after proportional and integral controller The instruction of side voltage all pressures

Step 1.3, the DC voltage v of detection electric power electric transformer isolation level outlet side_{dc_21}、v_{dc_22}、…、v_{dc_2i}, And obtain meansigma methodss v of this n DC voltage_2ave；

$v_{2\mathrm{ave}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{\mathrm{dc}\_2i}$

Step 1.4, meansigma methodss v of the isolation level outlet side DC voltage that step 1.3 is tried to achieve_2aveWith isolation level outlet side Direct voltage reference value v^* _{dc_2ref}Compare, its output obtains isolation level outlet side DC voltage after proportional and integral controller The instruction of meansigma methodss

Step 1.5, by the finger of each isolation level obtaining in step 1.2 dc-dc changer input side DC voltage all pressures OrderInstruction plus the isolation level outlet side DC voltage average value obtaining in step 1.4From And synthesize the final instruction of each isolation level dc-dc changer

The present invention is further improved by: the output side bus voltage Pressure and Control of electric power electric transformer isolation level are concrete Including following step of realizing:

Step 2.1, no matter electric power electric transformer connection is load or electrical network, using its electricity of conventional double -loop control Stream ring is output as total control instruction u of inverse cascade^* _m, in addition detect and obtain system output current i_l；

Step 2.2, by each module outlet side DC voltage value v of measured isolation level in step 1.3_{dc_1i}With obtain DC voltage average value v_2aveCompare, its output is after proportional controller with system output current i in step 2.1_lAnd inversion Total control instruction u of level^* _mIt is multiplied and obtain the instruction δ u of each DC voltage all pressures_{m_1}、δu_{m_2}、…、δu_{m_i}；

Step 2.3, by the instruction δ u of each DC voltage all pressures obtaining in step 2.2_{m_1}、δu_{m_2}、…、δu_{m_i} With total control instruction u of inverse cascade in step 2.1^* _mIt is added command value u obtaining each module of inverse cascade_{m_1}、u_{m_2}、…、u_{m_}i.

Compared with prior art, the method have the benefit that:

The present invention utilizes isolation level dc-dc converter control system to realize to isolation level input side DC voltage Pressure and Control With the control of isolation level outlet side DC voltage average value track reference voltage, using inverse cascade dc-ac converter control system Realize to isolation level outlet side DC voltage Pressure and Control.

Control method of the present invention can realize Pressure and Control between tandem type Monophase electric power electronic transformer cascade module, method Simply.Simulation results show correct, the reliability of the method, is engineer applied provides good reference value.

Brief description:

Fig. 1 is single-phase multi-module cascade dc-ac electric power electric transformer main circuit topology figure；

Fig. 2 is the control block diagram of isolation level input side DC voltage Pressure and Control part；

Fig. 3 is isolation level input side DC voltage Pressure and Control and outlet side DC voltage average value controls synthesis isolation level The control block diagram of overall control；

Fig. 4 realizes the control block diagram of isolation level outlet side direct current Pressure and Control for inverse cascade.

Fig. 5 is isolation level input side DC voltage simulation waveform.

Fig. 6 is isolation level outlet side DC voltage simulation waveform.

Specific embodiment:

With reference to shown in Fig. 1, the Monophase electric power electronic transformer system power main circuit of present invention application is by isolation level and inverse Become level composition: isolation level is high-frequency isolation type dc-dc changer, inverse cascade is dc-ac inverter.In order to meet medium-pressure or high pressure The requirement of grade, the input series connection medium-pressure or high pressure direct voltage source v of all dc-dc changers of isolation level_dc, outfan Connect the direct-flow input end of corresponding inverse cascade dc-ac inverter.All dc-ac inverter ac sides of inverse cascade adopt series system Connect output filter.

A kind of present invention Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method realize process include with Lower step: electric power electric transformer DC source side bus voltage Pressure and Control and electric power electric transformer isolation level output side bus Voltage Pressure and Control.

Wherein, electric power electric transformer DC source side bus voltage Pressure and Control specifically include following step of realizing:

Step 1.1, with reference to Fig. 1, detects electric power electric transformer DC voltage source (isolation level input side) each dc-dc Changer DC voltage v_{dc_11}、v_{dc_12}、…、v_{dc_1i}(i=1,2 ..., n), and obtain the meansigma methodss of this n DC voltage v_1aveReference value is all pressed using the DC side as in step 1.2；

$v_{1\mathrm{ave}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{\mathrm{dc}\_1i}$

Step 1.2, by each module DC voltage value v in step 1.1 measured_{dc_1i}(i=1,2 ..., n) ask together DC voltage meansigma methodss v going out_1aveCompare, its output obtains each dc-dc changer after proportional and integral controller The instruction of DC voltage all pressures(i=1,2 ..., n).Isolation level input side DC voltage is equal The control block diagram of pressure control section is as shown in Figure 2；

Step 1.3, the DC voltage v of detection electric power electric transformer isolation level outlet side_{dc_21}、v_{dc_22}、…、v_{dc_2i} (i=1,2 ..., n), and obtain meansigma methodss v of this n DC voltage_2ave；

$v_{2\mathrm{ave}}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{\mathrm{dc}\_2i}$

Step 1.4, meansigma methodss v of the isolation level outlet side DC voltage that step 1.3 is tried to achieve_2aveWith isolation level outlet side Direct voltage reference value v^* _{dc_2ref}Compare, its output obtains isolation level outlet side DC voltage after proportional and integral controller The instruction of meansigma methodss；

Step 1.5, by the finger of each isolation level obtaining in step 1.2 dc-dc changer input side DC voltage all pressures Order(i=1,2 ..., n) add that the isolation level outlet side unidirectional current obtaining in step 1.4 flattens The instruction of averageThus synthesizing the final instruction of each isolation level dc-dc changer (i=1, 2,…,n)；Isolation level input side DC voltage Pressure and Control and outlet side DC voltage average value control synthesis isolation level overall The control block diagram controlling is as shown in Figure 3.

The output side bus voltage Pressure and Control of electric power electric transformer isolation level specifically include following step of realizing:

Step 2.1, no matter electric power electric transformer connection is load or electrical network, using its electricity of conventional double -loop control Stream ring is output as total control instruction u of inverse cascade^* _m, in addition detect and obtain system output current i_l(referring to Fig. 1)；

Step 2.2, by each module outlet side DC voltage value v of measured isolation level in step 1.3_{dc_1i}(i=1, 2 ..., n) with the DC voltage average value v obtaining_2aveCompare, its output is after proportional controller with system in step 2.1 Output current i_lControl instruction u total with inverse cascade^* _mIt is multiplied and obtain the instruction δ u of each DC voltage all pressures_{m_1}、δ u_{m_2}、…、δu_{m_i}(i=1,2 ..., n)；

Step 2.3, by the instruction δ u of each DC voltage all pressures obtaining in step 2.2_{m_1}、δu_{m_2}、、δu_{m_i}(i =1,2 ..., n) with control instruction u that inverse cascade in step 2.1 is total^* _mIt is added command value u obtaining each module of inverse cascade_{m_1}、 u_{m_2}、…、u_{m_i}(i=1,2 ..., n).Inverse cascade realizes control block diagram such as Fig. 4 institute of isolation level outlet side direct current Pressure and Control Show.

In order to verify the effect of the present invention, we have been built altogether according to circuit shown in Fig. 1 by matlab/simulink There is the model of 9 h bridging parallel operations, wherein in the middle of each dab leakage inductance value have 10% difference, each DC side parallel etc. Effect loss resistance value has 50% difference.As shown in Figure 5 and Figure 6, Fig. 5 is isolation level input side DC voltage simulation waveform, Fig. 6 is isolation level outlet side DC voltage simulation waveform.In 0.25s, when the control method of the present invention is cut away, system DC voltage immediately begins to imbalance, in 0.28s, the control method of the present invention is put into again, through certain time Dynamic regulation, the DC voltage of system finally balances, and demonstrates effectiveness of the invention.

Claims (2)

1. a kind of Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method it is characterised in that: this Monophase electric power electricity The power main circuit of sub- transformator is made up of isolation level and inverse cascade, and wherein, isolation level is high-frequency isolation type dc-dc changer, Inverse cascade is dc-ac inverter；The input series connection medium-pressure or high pressure DC voltage of all dc-dc changers of isolation level Source, the direct-flow input end of the corresponding inverse cascade dc-ac inverter of output termination；All dc-ac inverter ac sides of inverse cascade are adopted Connect output filter with series system；This control method comprises the following steps: Monophase electric power electronic transformer DC source side bus Voltage Pressure and Control and the output side bus voltage Pressure and Control of Monophase electric power electronic transformer isolation level；

Wherein, Monophase electric power electronic transformer DC source side bus voltage Pressure and Control specifically include following step of realizing:

Step 1.1, detects each dc-dc changer DC voltage v of Monophase electric power electronic transformer isolation level input side_{dc_11}、 v_{dc_12}、…、v_{dc_1i}, and obtain meansigma methodss v of this n DC voltage_1aveReference is all pressed using the DC side as in step 1.2 Value, wherein, i=1,2 ..., n；

$v_{1ave}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{dc\_1i}$

Step 1.2, by each module DC voltage value v in step 1.1 measured_{dc_1i}With the direct current obtained in step 1.1 Side average voltage v_1aveCompare, its output obtains each dc-dc changer DC side electricity after proportional and integral controller The instruction of pressure all pressures

Step 1.3, the DC voltage v of detection Monophase electric power electronic transformer isolation level outlet side_{dc_21}、v_{dc_22}、…、v_{dc_2i}, And obtain meansigma methodss v of this n DC voltage_2ave；

$v_{2ave}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\σ}}}{v}_{dc\_2i}$

Step 1.4, meansigma methodss v of the isolation level outlet side DC voltage that step 1.3 is tried to achieve_2aveWith isolation level outlet side direct current Voltage reference value v^* _{dc_2ref}Compare, it is average that its output obtains isolation level outlet side DC voltage after proportional and integral controller The instruction of value

Step 1.5, by the instruction of each isolation level obtaining in step 1.2 dc-dc changer input side DC voltage all pressuresInstruction plus the isolation level outlet side DC voltage average value obtaining in step 1.4Thus Synthesize the final instruction of each isolation level dc-dc changer

2. a kind of Monophase electric power electronic transformer DC bus-bar voltage pressure equalizing control method according to claim 1, it is special Levy and be: the output side bus voltage Pressure and Control of Monophase electric power electronic transformer isolation level specifically include following step of realizing:

Step 2.1, no matter the connection of Monophase electric power electronic transformer is load or electrical network, using its electricity of conventional double -loop control Stream ring is output as total control instruction u of inverse cascade^* _m, in addition detect and obtain system output current i_l；

Step 2.2, by each module outlet side DC voltage value v of measured isolation level in step 1.3_{dc_1i}With the direct current obtained Average voltage v_2aveCompare, its output is after proportional controller with system output current i in step 2.1_lTotal with inverse cascade Control instruction u^* _mIt is multiplied and obtain the instruction δ u of each DC voltage all pressures_{m_1}、δu_{m_2}、…、δu_{m_i}；

Step 2.3, by the instruction δ u of each DC voltage all pressures obtaining in step 2.2_{m_1}、δu_{m_2}、…、δu_{m_i}Synchronous Total control instruction u of inverse cascade in rapid 2.1^* _mIt is added command value u obtaining each module of inverse cascade_{m_1}、u_{m_2}、…、u_{m_i}.