In this paper, a realization method for high-efficiency broadband power amplifier (PA) based on split-ring resonator (SRR) second harmonic output matching network (SHOMN) is presented. The SRR is composed of double rectangular rings, and it can flexibly match the second harmonic components to the high-efficiency impedance region in the Smith chart in a wide frequency band. Besides, the impedance transformation characteristic of SRR is derived, and the optimal output impedance is converted from the transistor drain to the output of SHOMN for accurate fundamental matching. For validation, a PA operating in 1.2–3.0 GHz is designed and fabricated for a 10-W GaN transistor. The measurement results show that the maximum efficiency can reach 78.3%; meanwhile, the average saturated output power is 41.0 dBm.
This paper investigates the impact of power converter station modeling
to high frequency overvoltage based on the on-site experimental test of
a fully operational 200 kV MMC-HVDC converter station. Artificial
short-circuit faults were generated in the system with hybrid DC circuit
breakers along coaxial cables by means of an unmanned aerial vehicle for
the first time. Fault transients recorded during the tests are found not
to comply with the typical framework where power stations are assumed to
present a high impedance, or at least dominated by the reactor
inductance. This discrepancy is proven to be caused by parasitic
elements at the terminals of the converter station, resulting in a
spurious low-frequency resonance dominating fault transients. A wideband
converter station model is proposed and validated by the test data. The
simulation results show that the proposed wideband model should be
adopted avoiding the risk of huge resonance bias in short line distance.
When fault distance is 10 km away, converter station model will converge
to standard AVM, while the high impedance or reactor model is no longer
valid. The experimental data provide a benchmark to validate the
converter station model for transient overvoltage or electromagnetic
interference under the fault condition.
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