電力專業(yè)英語閱讀-作業(yè)七

1、作業(yè)七:將下列段落翻譯成中文Frequency StabilityFrequency stability refers to the ability of a power system to maintain steady frequency following a severe system upset resulting in a significant imbalance between generation and load. It depends on the ability to maintain/restore equilibrium between system generat

2、ion and load, with minimum unintentional loss of load. Instability that may result occurs in the form of sustained frequency swings leading to tripping of generating units and/or loads. Severe system upsets generally result in large excursions of frequency, power flows, voltage, and other system var

3、iables, thereby invoking the actions of processes, controls, and protections that are not modeled in conventional transient stability or voltage stability studies. These processes may be very slow, such as boiler dynamics, or only triggered for extreme system conditions, such as volts/Hertz protecti

4、on tripping generators. In large interconnected power systems, this type of situation is most commonly associated with conditions following splitting of systems into islands. Stability in this case is a question of whether or not each island will reach a state of operating equilibrium with minimal u

5、nintentional loss of load. It is determined by the overall response of the island as evidenced by its mean frequency, rather than relative motion of machines. Generally, frequency stability problems are associated with inadequacies in equipment responses, poor coordination of control and protection

6、equipment, or insufficient generation reserve.In isolated island systems, frequency stability could be of concern for any disturbance causing a relatively significant loss of load or generation. During frequency excursions, the characteristic times of the processes and devices that are activated wil

7、l range from fraction of seconds, corresponding to the response of devices such as underfrequency load shedding and generator controls and protections, to several minutes, corresponding to the response of devices such as prime mover energy supply systems and load voltage regulators. Therefore, frequ

8、ency stability may be a short-term phenomenon or a long-term phenomenon. During frequency excursions, voltage magnitudes may change significantly, especially for islanding conditions with underfrequency load shedding that unloads the system. Voltage magnitude changes, which may be higher in percenta

9、ge than frequency changes, affect the load-generation imbalance. High voltage may cause undesirable generator tripping by poorly designed or coordinated loss of excitation relays or volts/Hertz relays. In an overloaded system, low voltage may cause undesirable operation of impedance relays.頻率穩(wěn)定度頻率穩(wěn)定

10、度是指一種電力系統(tǒng),以保持穩(wěn)定的頻率下產(chǎn)生的生成和負(fù)載之間的顯著不平衡嚴(yán)重系統(tǒng)心煩的能力。這取決于維持/恢復(fù)系統(tǒng)生成和負(fù)載之間的平衡,帶負(fù)載最小意外損失的能力。不穩(wěn)定,可能會導(dǎo)致發(fā)生在持續(xù)的頻率波動導(dǎo)致跳閘生成單元和/或負(fù)載的形式。嚴(yán)重系統(tǒng)混亂通常導(dǎo)致頻率,功率流,電壓,和其他系統(tǒng)變量的大偏移,由此調(diào)用的過程,控制和保護(hù)未在常規(guī)過渡穩(wěn)定性或電壓穩(wěn)定性研究建模的操作。這些過程可能很慢,如鍋爐動力學(xué),或只觸發(fā)極端系統(tǒng)條件,如伏特/赫茲保護(hù)跳閘發(fā)電機(jī)。在大型互連的電力系統(tǒng)中,這種情況是最常見的以下條件的系統(tǒng)分裂成島嶼相關(guān)聯(lián)。在這種情況下,穩(wěn)定是每個(gè)島是否會達(dá)到操作平衡狀態(tài)與負(fù)載的最小意外丟失的問題。它是由島的總響應(yīng)就證明了它的平均頻率,而不是機(jī)械的相對運(yùn)動確定的。一般來說,頻率穩(wěn)定度問題,在設(shè)備的反應(yīng),控制和保護(hù)設(shè)備,或不足一代,儲備的協(xié)調(diào)性差的不足有關(guān)。在孤島系統(tǒng),頻率穩(wěn)定度可能會關(guān)注任何干擾造成一個(gè)相對顯著損失負(fù)荷或產(chǎn)生的。期間的頻率偏移,這被激活將范圍從幾秒鐘分?jǐn)?shù),對應(yīng)于諸如低頻減載和發(fā)電機(jī)的控制和保護(hù)設(shè)備的響應(yīng),到幾分鐘的過程和設(shè)備的特征時(shí)間,對應(yīng)于裝置,例如響應(yīng)作為原動機(jī)的能源供應(yīng)系統(tǒng)和負(fù)載電壓調(diào)節(jié)器