【正文】 d and also helps maintain synchronism of the generator with the power system by increasing synchronizing torque when required. In stable steady state operation, a power system has an exact match of mechanical power delivered to generators and electrical power consumed by loads. Further。s turbine governor control, system frequency, and interchange schedules and dispatches corrections to the unit39。 過去電力系統(tǒng)故障的簡潔描述就是發(fā)電機(jī)勵(lì)磁、渦輪機(jī)、調(diào)速器及電力系統(tǒng)控制也包括在內(nèi)。高架線是組任何電力系統(tǒng)的重要組成部分而瞬時(shí)性故障是由于種種原因而發(fā)生的。繼電器的誤動可能會導(dǎo)致不必要的動作或系統(tǒng)的大干擾。如果 機(jī) 端電壓是 穩(wěn)定的，增加勵(lì)磁 電流 將增加同步 機(jī)械 轉(zhuǎn)矩，并增加了無功功率的輸出。輔助控制 包括以下幾個(gè)方面： 最大 /最小勵(lì)磁級別限制（有機(jī)電致發(fā)光 /梅爾分別是，這些限制可能是十分之一依賴 ） ； 定子電流限制，以防止定子 過 熱超負(fù)荷 ； 伏特每赫茲的限制，以防止 由于潮流過剩導(dǎo)致 設(shè)備損壞 ； 機(jī) 端電壓限制，以防止由于過量介質(zhì)應(yīng)力設(shè)備損壞 ； 線下降的補(bǔ)償， 對于 系統(tǒng)電壓凹陷以增加發(fā)電機(jī)的反應(yīng) ； 無功控制發(fā)電機(jī)試圖規(guī)范相同參數(shù) ； 電力系統(tǒng)穩(wěn)定，從而抑制低頻 振動 ； 振蕩 上限 (UEL），以保護(hù)對發(fā)電機(jī)定子端部繞組 發(fā)熱 ，同運(yùn)行于 振蕩 模式 [15]。這些輔助控制，可確保即使根據(jù)自 動調(diào)節(jié)的一個(gè)主要參數(shù)，發(fā)電機(jī) 總是能運(yùn)行 在其能力范圍內(nèi)。 A：勵(lì)磁控制 ： 發(fā)電機(jī) 的 勵(lì)磁系統(tǒng)提供能源 建立 磁場 從而 使發(fā)電機(jī)與電力系統(tǒng) 保持同步 。 即使成功的排除了故障，有時(shí)候由于線路過負(fù)荷、無功缺額、不適合的繼電裝置仍能導(dǎo)致繼電器的誤動。 很多系統(tǒng)干擾可以歸因于運(yùn)行極限和在生產(chǎn)、輸電的少量冗余及配電能力。 從過去發(fā)生的主要事故中我們知道在發(fā)生故障的瞬間與發(fā)電機(jī)有關(guān)的保護(hù)有可能會動作。 aP accelerating power. The mechanical power mP is provided by the turbine and the average mechanical power must be equal to the average electrical power. When a system disturbance occurs, there is a change in one of the parameters of the electrical power equation. For faults, typically, the reactance between the generator and the load( tX )， the load voltage( tE )， or some bination of these two parameters causes the electrical power to change. For example, for a short circuit, the load voltage is reduced。 reactive power sharing controls for generators trying to regulate the same parameter。There are a variety of control functions that can be applied to the excitation system, including automatic voltage regulation (AVR), constant power factor regulation, and constant reactive power regulation. The excitation system may also operate in manual control with no automatic regulation. All of the automatic control modes may have supplementary controls. These supplementary controls may ensure that even under automatic regulation of a primary parameter, the generator is always operated within its capability limits. Supplementary controls may also enhance the stable operation of the generator in parallel with a power system. Supplementary controls may include the following: maximum and/or minimum excitation level limits (OEL/MEL respectively, these limits may be tithe dependent)。 the voltage is regulated within narrow limits. Small disturbances resulting in. power or voltage oscillations are quickly damped. Frequency is maintained within acceptable limits by turbine governor controls and sometimes by system load control as noted in other sections of this paper. During Large disturbances, excitation controls act to maintain system stability, For major disturbances. the terminal voltage change is sufficient that the output of the excitation is either full on, at ceiling, or full off. The AVR is the main control function in most cases, but the supplementary controls provide important features. Large system disturbances are typically caused by short circuits of different types. The opening of appropriate highspeed breakers isolates the fault. During the fault, the terminal voltage dips and, in response, the exciter increases its output voltage to ceiling which causes the excitation current into the field to increase at a rate determined by the voltage divided by the inductance of the field. System disturbances are also caused when a generation unit is suddenly dropped or when a breaker is suddenly opened and a load is dropped. When a unit is dropped, other nearby units pick up the load of the dropped unit and in response to the drop in mercurial voltage, the excitation of each of these units will increase When a breaker is suddenly opened and a load is dropped, the excitation will be reduced. The electrical power eP transferred from the generator, an electric machine, to the load is given by the equation tt si neEEP X ??? () where E internal voltage and is proportional to the excitation current。s turbine governor controllers accordingly. During some system disturbances where interconnected regions may bee separated, scheduled interchanges can no longer be maintained during the immediate post disturbance time frame. If AGC is still in service, it may adjust turbine governors in a fruitless attempt to maintain scheduled interchanges through transmission paths that no longer exist. Such blind AGC action may result in unacceptable load flows or system frequency deviations. Special protection systems applied for system protection purposes may include control actions to suspend AGC until interchange schedules can be readjusted and/or transmission paths restored to service. When AGC is suspended, the turbine governor speed references remain fixed and system frequency is brought back to near normal by system control actions acting together with turbine governor control actions using the fixed speed references. It can be seen therefore that because of limited individual effect on system frequency, turbine governor controls have less interaction with system and/or generator protection systems than generator excitation controls. However, proper setting of the governor controls is critical for maintenance of acceptable system frequency and reasonable unit load division after disturbances. Further, turbine governor controls may bee an integral part of special protection systems to maintain acceptable system performance in the post disturbance period. C. System Control： System control actions are usually expected to mitigate the effect of disturbances before any equipment (including generators) bees in danger of being physically damaged. 39。這篇文章的主題就是討論在系統(tǒng)期間運(yùn)行的發(fā)電機(jī)保護(hù)功能。 電力系統(tǒng)的穩(wěn)定運(yùn)行需要不斷地檢查能量供應(yīng)和系統(tǒng)負(fù)荷的平衡