供配電系統(tǒng)外文翻譯(2)-其他專(zhuān)業(yè)(編輯修改稿)
2025-02-24 07:26 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 nsformers. The extensive use of electric clocks and the use of frequency for other timing purpose require accurate maintenance of synchronous time which is proportional to integral. A change in active power demand at one point is reflected throughout the system by a change in frequency. Because there are many generators supplying power into system, some means must be provided to allocate change in demand to the generators. A speed governor on each generating unit provides the primmy speed control function, while supplementary control origination at a central control center allocates generation. In an interconnected system with two or more independently controlled areas, in addition to control of frequency, the generation within each area has to be controlled so as to maintain scheduled power interchange. The control of generation and frequency is monly referred to as loadfrequency control (LFC). The control measures of power and frequency include: (1) Regulation of the generator speed governor (2) Underfrequency load shedding (3) Automatic generation control (AGC) AGC is an effective means for power frequency control in largescale power systems. In an Interconnected power system, the primary objectives of AGC are to regulate frequency to the specified nominal value and to maintain the interchange power between control area at the scheduled values by adjust the output of the selected generators. This function is monly referred to as loadfrequency control. A secondary objective is to distribute the required change in generation omong units to minimize operating costs. For efficient and reliable operation of power system, the control of voltage and reactive power should satisfy the following objectives: (1) Voltages at the terminals of all equipment in the system are within acceptable limits. Both utility equipment and customer equipment are designed to operate at a certain voltage rating. Prolonged operation of the equipment at voltages outside the allowable rang could adversely affect their performance and possibly cause them damage. (2) System stability is enhanced to maximize utilization of the transmission system. (3) The reactive power flow is minimzed as to reduce the equipment and the transmission lines losses to a practical minimum.
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