【正文】 4 EXPERIMENTAL RESULTS A test rig was set up to verify the theoretical derivations above. An active power filter is implemented with the current reference of Eq.(15) used as an input to the filter and the digital signal processing of the voltages and currents is implemented using a 32 bit floating point DSP, TMS 320C31. The configuration of the experimental setting is shown in . The nonlinear of the single phase power system under experimentation is a diode bridge rectifier with an RL load connected to the dc side. The ac to dc converter is rated at 25 kVA. An inductor, L, with a value of mH and a capacitor with a value of 10,000 181。F are used as dc output filter.. The output current of the active power filter is controlled by a hysteresis parator to confine the switching frequency to 15 kHz. shows the waveforms of the load current, the pensating current of the active power filter and the supply current. It is clear that active power filter performed its task of pensating for the harmonic distortion as the supply current is converted to a pseudosinusoidal waveform from its original square shape waveform. The top waveform in shows the original supply current waveform and the bottom waveform shows the supply current wave form after the implementation of the active power filter. The middle wave form is the pensating current of the active power filter. 5 CONCLUSIONS A novel strategy, orthogonal transformation technique, is used to yield reference current expressions for the active power filter of a single phase power supply feeding a solid state power converter, in terms of the supply voltage and current. The power active filter control strategy could pensate for either the harmonic distortion of the supply current or the reactive power or both. Experimental results demonstrated the effectiveness of the novel active power filter control strategy. 6 REFERENCES 1. Akagi, H., Kanazawa, Y. and Nabae, A., Generalized Theory of the Instantaneous Reactive Power in Three Phase Circuits, Proceedings IPEC83 Conference, Tokyo (J8), Sept. 1983, pp 13751386. 2. Dobrucky, B., Analysis and Modelling of Power Semiconductor in Steady and Transient States, PhD Thesis, University of Zilina, Slovak Republic, 1985. 3. Kim, H. and Akagi, H., The Instantaneous Power Theory on the Rotating pqr Reference Frame, Proceeding of PEDS’99 Conference, . 4. Kim, H., Blaabjerg, F., BakJensen, B. and Choi J., Novel Instantaneous Compensation Theory in Three Phase Systems, Proceedings of EPE’01 Conference, Graz (Austria), . 5. Akagi, H., Kanazawa and Nabae, Instantaneous reactive Power Compensators Comprising Switching Devices Without Energy Storage Components, IEEE Transactions on AI, , 1984, , pp 625630. Power System Harmonic Fundamental Considerations: Tips and Tools for Reducing Harmonic Distortion in Electronic Drive Applications Larry Ray, PE。 that is, by turning on and off in a manner not proportional to the applied instantaneous voltage, their kW/kVA relationship is not equal to the phase angle between fundamental voltage and current. This peculiarity, in fact, has required the establishment of two power factor definitions. These two power factors are equal for undistorted (sinusoidal) voltages and currents Displacement Power Factor (dPF) – Cosine of the phase angle between fundamental voltage and fundamental current. Total (sometimes referred to as “True”) Power Factor (tPF) – Real power (kW) divided by apparent power (kVA). Power factor correction capacitors primarily affect the displacement power factor for a circuit. If PFC’s are applied on a circuit that already has a high dPF, then the fundamental current ponent could be shifted into a leading relationship to fundamental voltage. This situation can result in voltage regulation and distortion problems for the circuit. In addition, the addition of large PFC’s on a PWM circuit can also increase the likelihood of harmonic resonance problems, and the resulting excessive voltage distortion issues introduced earlier. Harmonic Mitigation – Two Passive Techniques Harmonics Attenuation The earlier voltage and current distortion discussion, and voltage distortion estimates assume that the current distortion remains unchanged regardless of the circuit impedance, but this is not entirely true. Harmonic current distortion is affected by the amount of circuit impedance. In fact, an engineer will discover that placing the same harmonic producing load at two different nodes in a power system will result in two different levels of load current distortion. Power system designers can utilize this effect, called attenuation, as one method of passive harmonic mitigation. The current waveforms below show the effects of introducing a series line reactor (“choke”) at the terminals of a 100 hp pulsewidth This attenuation effect is often employed to reduce the harmonic distortion associated with threephase ASD’s. The ASD operation is not adversely affected, provided the line reactor chosen for the application does not exceed about 5% impedance (relative to the drive base). Harmonics Cancellation In addition to attenuation, harmonic current distortion can be reduced by cancellation. Cancellation occurs because individual harmonic ponents of a distorted current are affected differently when passing through normal power system transformers. The magnitude of harmonic currents, like the 60Hz ponent, increases or decreases consistent with the transformer turns ratio. The phase angle of harmonic ponents, however, is influenced by the type of connection of the three phase transformer. The 5th and 7th ponents, for example, experience a 3017