风力发电机外文文献翻译--小规模发电pmsg风力涡轮转换器矢量控制英文(编辑修改稿)

风力发电机外文文献翻译--小规模发电pmsg风力涡轮转换器矢量控制英文(编辑修改稿)内容摘要：

is method. Therefore it will achieve a better estimation by adding a lowpass filter (LPF), as shown in Fig. 5. filtersusiEMF calculationde∧qe∧divider arctangentintegratorPI controllerθΔLPFθ∧ω∧ Fig. 5. Block diagram of sensorless vector control based on digital PLL B. Vector control of PMSG In order to study the torque control of PMSG, it is necessary to establish a mathematical model. Because qaxis leads daxis 90176。 in the DQ coordinate system, the generator voltage equation can be expressed as [8]: sdsd s sd d sq sqsqsq sq q d sddiuRiL LidtdiuRiL Lidtωωωψ⎧=+ −⎪⎪⎨⎪=+ + +⎪⎩ (3) The significance of various physical quantities in (3) is the same as in (1). The generator electromagic torque equation can be expressed as: 33()22esqdqsdqTpi pLLiiψ=+− (4) where p is the number of generator pole pairs, and ψ is the magic flux. Based on the above mathematical model, the sensorless vector control program of PMSG is established, and its control block diagram is shown in Fig. 6. *ωωˆθˆ*sdi*sqisdˆisqˆi*sdˆu*sqˆusaisbiIparkIclarkPark Clark Fig. 6. Sensorless vector control block diagram of PMSG Generator rotor position and speed which are estimated by sensorless algorithm can be used in vector control. The reference value of motor torque can be obtained by the speed 4controller. The voltage reference of generator can also be got by current controller, and then the control signals of rectifier switching device can be obtained by a set of PWM modulation algorithms. The position and speed of generator rotor which is necessary to vector control is obtained by sensorless algorithm. C. Singlephase gridconnected PLL Fig. 7 shows the block diagram of the singlephase girdconnected PLL. In order to ensure that the converter output voltage is in the same phase with the output current, the PLL is used to achieve unity power factor control. At the same time, the converter also provides the angle of the reference current transformation [5]. ffω∫ωPLLθθω Fig. 7. The block diagram of the singlephase PLL The transformation between orthogonal ab and DQ reference frames can be described by trigonometric relations, which are given in (5) and (6), and the rotating reference frame is shown in Fig. 8. Fig. 8. Definition of rotating reference frame ⎥⎦⎤⎢⎣⎡⎥⎦⎤⎢⎣⎡−=⎥⎦⎤⎢⎣⎡baqdffffθθθθcossinsincos (5) ⎥⎦⎤⎢⎣⎡⎥⎦⎤⎢⎣⎡ −=⎥⎦⎤⎢⎣⎡qdbaffffθθθθcossinsincos (6) Active power and reactive power equations can be expressed as: ⎩⎨⎧−=+=dqqdqqddivivQivivP (7) If the phase voltage and qaxis coincide, then 0=dv and vvq= , active power and reactive power equations can be simplified as: ||||qdP viQvi=⎧⎪⎨=−⎪⎩ (8) D. The vector control strategy of the gridside inverter For a three phase converter, simple PI pensators designed in a DQ synchronous frame can achieve zero steady state error at the fundamental frequency, but this method is not applicable to singlephase power converter because there is only one phase variable available in a singlephase power converter, while the DQ transformation needs at least two orthogonal variables. In order to construct the additional orthogonal phase information from the original singlephase power converter, the imaginary orthogonal circuit is developed, as shown in Fig. 9. The imaginary orthogonal circuit has exactly the same circuit ponents and parameters, but the current bi and the voltage be , maintain 90D phase shift with respect to their counterparts in the real circuit ai and ae [6]. vaRL+eaUdc+vbRL+ebReal CircuitImaginary Circuitaibi Fig. 9. Real circuit and its imaginary orthogonal circuit From Fig. 9, the voltage equation can be expressed as: ⎥⎦⎤⎢⎣⎡−−+⎥⎦⎤⎢⎣⎡⎥⎦⎤⎢⎣⎡−=⎥⎦⎤⎢⎣⎡bbaababaveveLiiLRiip11001 (9) Transforming the voltage equations into the synchronous reference frame using (5) and (6), and considering 0=dv and vvq= , we have: ⎥⎦⎤⎢⎣⎡−+⎥⎦⎤⎢⎣⎡⎥⎦⎤⎢⎣⎡−−−=⎥⎦⎤⎢⎣⎡||1//veeLiiLRLRiipqdqdqdωω (10) To achieve decoupled control of active power and reactive power, the output voltage of the inverter in the synchronous reference frame can be expressed as: ||)(1vixLedq+−= ω (11) )(2 qdixLe ω+= (12) Substituting (11) and (12) into (10), system equations can be rewritten as follows: 5⎥⎦⎤⎢⎣⎡+⎥⎦⎤⎢⎣⎡⎥⎦⎤⎢⎣⎡−=⎥⎦⎤⎢⎣⎡2。