正確保護(hù)發(fā)電機(jī)很重要

　　Proper protection of the generator is crucial

　　如何正確的保護(hù)發(fā)電機(jī)對(duì)于發(fā)電機(jī)可能發(fā)生的故障和不正常工作狀態(tài),應(yīng)根據(jù)發(fā)電機(jī)的容量有選擇地裝設(shè)以下保護(hù)。

　　How to correctly protect the generator from possible faults and abnormal working conditions? The following protections should be selectively installed according to the capacity of the generator.

　　(1)縱聯(lián)差動(dòng)保護(hù):為定子繞組及其引出線的相間短路保護(hù)。

　　(1) Longitudinal differential protection: It is a phase to phase short circuit protection for the stator winding and its outgoing lines.

　　(2)橫聯(lián)差動(dòng)保護(hù):為定子繞組一相匝間短路保護(hù)。只有當(dāng)一相定子繞組有兩個(gè)及以上并聯(lián)分支而構(gòu)成兩個(gè)或三個(gè)中性點(diǎn)引出端時(shí),才裝設(shè)該種保護(hù)。

　　(2) Horizontal differential protection: It is used for short circuit protection between one phase and one turn of the stator winding. This type of protection is only installed when a phase stator winding has two or more parallel branches forming two or three neutral point terminals.

　　(3)單相接地保護(hù):為發(fā)電機(jī)定子繞組的單相接地保護(hù)。

　　(3) Single phase grounding protection: provides single-phase grounding protection for the stator winding of the generator.

　　(4)勵(lì)磁回路接地保護(hù):為勵(lì)磁回路的接地故障保護(hù)。

　　(4) Excitation circuit grounding protection: provides grounding fault protection for the excitation circuit.

　　(5)低勵(lì)、失磁保護(hù):為防止大型發(fā)電機(jī)低勵(lì)(勵(lì)磁電流低于靜穩(wěn)限所對(duì)應(yīng)的勵(lì)磁電流)或失去勵(lì)磁(勵(lì)磁電流為零)后,從系統(tǒng)中吸收大量無功功率而對(duì)系統(tǒng)產(chǎn)生不利影響,100MW及以上容量的發(fā)電機(jī)都裝設(shè)這種保護(hù)。

　　(5) Low excitation and demagnetization protection: To prevent large generators from absorbing a large amount of reactive power from the system and causing adverse effects after low excitation (excitation current below the static stability limit) or loss of excitation (excitation current is zero), generators with a capacity of 100MW and above are equipped with this protection.

　　(6)過負(fù)荷保護(hù):發(fā)電機(jī)長時(shí)間超過額定負(fù)荷運(yùn)行時(shí)作用于信號(hào)的保護(hù)。中小型發(fā)電機(jī)只裝設(shè)定子過負(fù)荷保護(hù);大型發(fā)電機(jī)應(yīng)分別裝設(shè)定子過負(fù)荷和勵(lì)磁繞組過負(fù)荷保護(hù)。

　　(6) Overload protection: The protection applied to the signal when the generator operates beyond its rated load for a long time. Small and medium-sized generators are only equipped with set sub overload protection; Large generators should be equipped with stator overload and excitation winding overload protection separately.

　　(7)定子繞組過電流保護(hù):當(dāng)發(fā)電機(jī)縱差保護(hù)范圍外發(fā)生短路,而短路元件的保護(hù)或斷路器拒絕動(dòng)作,這種保護(hù)作為外部短路的后備,也兼作縱差保護(hù)的后備保護(hù)。

　　(7) Stator winding overcurrent protection: When a short circuit occurs outside the longitudinal differential protection range of the generator, and the protection of the short-circuit component or the circuit breaker refuses to operate, this protection serves as a backup for external short circuits and also serves as a backup for longitudinal differential protection.

　　?(8)定子繞組過電壓保護(hù):用于防止突然甩去全部負(fù)荷后引起定子繞組過電壓,水輪發(fā)電機(jī)和大型汽輪發(fā)電機(jī)都裝設(shè)過電壓保護(hù),中小型汽輪發(fā)電機(jī)通常不裝設(shè)過電壓保護(hù)。

　　(8) Stator winding overvoltage protection: used to prevent stator winding overvoltage caused by sudden shedding of all loads. Both hydro generators and large steam turbine generators are equipped with overvoltage protection, while small and medium-sized steam turbine generators usually do not have overvoltage protection.

　　(9)負(fù)序電流保護(hù):電力系統(tǒng)發(fā)生不對(duì)稱短路或者三相負(fù)荷不對(duì)稱(如電氣機(jī)車、電弧爐等單相負(fù)荷的比重太大)時(shí),會(huì)使轉(zhuǎn)子端部、護(hù)環(huán)內(nèi)表面等電流密度很大的部位過熱,造成轉(zhuǎn)子的局部灼傷,因此應(yīng)裝設(shè)負(fù)序電流保護(hù)。

　　(9) Negative sequence current protection: When an asymmetric short circuit or three-phase load asymmetry occurs in the power system (such as in electric locomotives, arc furnaces, etc. where the proportion of single-phase loads is too high), it can cause overheating in areas with high current density such as the rotor end and the inner surface of the protective ring, resulting in local burns to the rotor. Therefore, negative sequence current protection should be installed.

　　(10)失步保護(hù):反應(yīng)大型發(fā)電機(jī)組與系統(tǒng)振蕩過程的失步保護(hù)。

　　(10) Out of step protection: It reflects the out of step protection of large generator sets and system oscillation processes.

　　(11)逆功率保護(hù):當(dāng)汽輪機(jī)主汽門誤關(guān)閉,或機(jī)爐保護(hù)動(dòng)作關(guān)閉主汽門而發(fā)電機(jī)出口斷路器未跳閘時(shí),從電力系統(tǒng)吸收有功功率而造成汽輪機(jī)事故,故大型機(jī)組要裝設(shè)用逆功率繼電器構(gòu)成的逆功率保護(hù),用于保護(hù)汽輪機(jī)。

　　(11) Reverse power protection: When the main steam valve of the steam turbine is mistakenly closed, or when the boiler protection action closes the main steam valve but the generator outlet circuit breaker does not trip, it absorbs active power from the power system and causes a steam turbine accident. Therefore, large units need to install reverse power protection composed of reverse power relays to protect the steam turbine.

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