Aiming at the case of large frequency fluctuation in natural gas unit black start project, combining with the gas black start system and the waveform diagram during static frequency convertor (SFC) startup, the failure phenomenon is described in detail and the specific cause of the failure is analyzed. On the basis of considering the slow response speed of diesel generator unit, a super capacitor-assisted black start frequency modulation (FM) strategy is proposed. The SFC power is divided into base power and frequency fluctuation power, among which the base power is borne by the diesel generator unit to ensure stable operation of the system, and the frequency fluctuation power is quickly responded by the supercapacitor to suppress the frequency fluctuation effectively. Through the black start experiment of a 4F gas unit, the strategy not only effectively reduces the frequency fluctuation during the black start process, but also avoids the overcurrent fault during ramp-up and load-change phase, thus the reliability and safety of black start of the gas unit is improved.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |