【正文】 ucing the tripping time for faults on the upstream work. To counterbalance these advantages however, it requires pilot links (SOLKORRF) and matched class X current transformers are generally remended with stabilising resistors for the differential protection of transformers, rotating machines and busbars. The differential relays for cable protection, type SOLKORRF, operate on a special principle ? They do not pare individually the currents in each phase, but rather a bination of the three currents. ? The advantage of this system is that only one pair of pilot wires is required, but the operating levels are different for faults on different phases. Directional protection When a substation is supplied by two cables or two transformers in parallel, the protection on these two feeders (in the upstream substation) would operate simultaneously for a fault affecting one of them. To obtain selective protection it is necessary to use either differential or directional relays. In the latter case phase directional overcurrent relays type RMSD7921 or ITD7111 should be installed on each iner. The directional element of these relays checks the phase angle between the current and voltage of one phase, and allows the overcurrent unit to operate if this phase angle indicates current in the reverse direction. RMSD 7000 relays, with the FFT input signal treatment, check the phase angle between the fundamental of current and voltage. As a result they remain stable and selective even in works containing high levels of harmonics. The time delay of the directional relay is chosen to be selective with the upstream relays, and thus the loop is first opened (by tripping the correct LV breaker), followed by the upstream protection isolating the faulty feeder. Alternatively, the upstream breaker may be opened by sending an intertrip signal from the LV directional relay to accelerate fault elimination. 1 簡介 繼電保護(hù)裝置可以認(rèn)為是 電力 系統(tǒng)設(shè)備 裝置中的大腦 部分。 DISTRIBUTION NETWORKS Protective relays play an important role in the operation of industrial works. If they are correctly applied they provide protection of both equipment and personnel together and ensure the best possible quality of electrical power supply. The object of this guide is to define the protective relays that are the most suited to the layout of the electrical power system work (parallel operation of production units or stepdown substations, ringmain or radial distribution, type of work earthing, etc.). Reference is made to various types of overcurrent relays: ? ITG, RMS and RMSA series. ? ITG relays are classical solid state overcurrent and earth fault relays. RMS and RMSA relays are microprocessor based relays which use an original method of analysing input current signals。 為了使 電力系統(tǒng)的 穩(wěn)定性和安全性達(dá)到最 優(yōu)化 的 需求 ， 規(guī)定我們 在靠近電力線路斷路器側(cè) 配置 使用 獨(dú)立的 繼電器 來控制 。 歐洲各國發(fā)展基于 PROCOM 技術(shù)的 數(shù)字 繼電器 ， 在 不犧牲古典固態(tài)繼電器的獨(dú)立能力如 ITG 和 TTG 系列 繼電器 的基礎(chǔ)上提高它的性能 。同時，對器件的穩(wěn)定性和安全的性的要求也在不斷的提高。 對第一個問題的答案則 決定了 保護(hù)類型的選擇和他們的 保護(hù)范圍的 設(shè)定。 2 高電壓工業(yè)和配電網(wǎng)絡(luò)的保護(hù) 繼電保護(hù)在電能 網(wǎng)絡(luò)中扮演這非常重要的角色，他們是否能夠 對 器件和全體設(shè)備 作出正確的保護(hù)動作 ，這為能否提供高質(zhì)量 電能提供了 保證。使用 這種繼電器時需要考慮大量諧波電流的 有效值。他們必須要能夠快速的感知 在短路情況下產(chǎn)生的 電流 沖擊變化量 并 在 短時間內(nèi) 做出 正確的反應(yīng) （ 還要考慮到 電應(yīng)力和熱應(yīng)力 的承受范圍 ） 它的另一個基礎(chǔ)特性就是 選擇性 ,能夠正確反應(yīng) 故障處 短路 以 維持供電 網(wǎng)絡(luò)的健康穩(wěn)定。但是 ， 這 還是有一些 不足 之處，如 最 靠近電 源 處 故障清除時間 會 增加 ， 且短路 電路電流非常的大 。 分級間隔可能會減少如果需要 ,時間小于 1秒， 使用繼電器與高穩(wěn)定性定時器電路 則在 250ms左右 (ITG 7000或均方根 700/7000繼電器 )。故障清除時間是獨(dú)立于它的位置 ， 繼電器最低操作時間 僅 作為一個 與下級信息傳送速度有關(guān)的一個 函數(shù) 。 差動保護(hù) 這一保護(hù)的原則是比較同一相上電流的大小，單由兩個繼電保護(hù)裝置來執(zhí)行保護(hù)。 獲得選擇性保護(hù)很有必要利用微分或方向繼電器。結(jié)果他們保持穩(wěn)定和選擇性甚至在網(wǎng)絡(luò)含有高水平的