Parallel operation of the hottest generator

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Parallel operation of generator

1 The voltage effective value UF of the generator to be paralleled is equal to or nearly equal to the voltage effective value u of electricity, and the allowable difference is ± 5% of the rated voltage value

the voltage difference between the voltage effective value UF of the generator to be paralleled and the voltage effective value u of electricity Δ U. If it is within the allowable range, the reactive impulse current caused is allowed. otherwise Δ The greater u is, the greater the impulse current is. This process is equivalent to a sudden short circuit of the generator. Therefore, the voltage between the two must be adjusted to make them close to the same before they can be paralleled

 2. The cycle FF of the generator to be connected shall be equal to the cycle F of electricity, but the allowable difference is within ± 0.05 ~ 0.1 cycle/s

if the two cycles are not equal, active impulse current will be generated, which will increase or decrease the speed of the generator, resulting in vibration of the generator shaft. If the cycle wave difference exceeds the allowable value and is large, it will cause the relative speed between the rotor pole and the stator pole to be too large, which is not easy to pull each other and easy to lose step. Therefore, when the generator to be paralleled, the cycle must be adjusted to the allowable range. Usually, the cycle of the generator to be paralleled is slightly higher than the cycle of electricity, so that the generator can be easily pulled into synchronization, and part of the load can be carried immediately after paralleling

    3. The phase of the voltage of the generator to be paralleled is the same as that of the electric voltage, that is, the phase angle is the same

when the generator is in parallel, if the phases of the two voltages are inconsistent, the resulting impulse current may reach 20 ~ 30 times the rated current, so it is very dangerous. The impact current can be divided into active and reactive components. The impact of active current will not only increase the burden of the steam turbine, but also may cause the steam turbine to be subjected to great mechanical stress. In this way, not only the generator to be paralleled cannot be pulled into synchronization, but also other generators running in parallel may lose synchronization

when quasi synchronous paralleling is adopted, the impulse current of the generator is very small. Therefore, the phase angle difference should generally be controlled within 10 º. At this time, the impulse current is about 0.5 times that of the generator rated current deposit system, which is also the most effective means for governments to promote the forced classification of garbage

    4. The phase sequence of the voltage of the generator to be paralleled must be consistent with the phase sequence of the electrical voltage

    5. The voltage waveform of the generator to be paralleled shall be consistent with that of the electric voltage

the problem of phase sequence in Item 4 of the above conditions requires that when installing the generator, determine the phase sequence of the generator according to the specified rotation of the generator. Therefore, in the later parallel process, the problem of phase sequence does not need to be considered. Item 5 is about the voltage waveform, which should be ensured in the process of whether the generator production machine is able to be manufactured

to sum up, when the generator is in parallel, it mainly meets the conditions of 1 ~ 3, otherwise it will cause serious accidents. In the process of parallel closing, when the voltage, cycle and phase angle of generator and electricity are close to but not equal, the small impulse current caused by this is still allowed. After closing, the generator can be pulled into synchronization under the "self-adjusting step"

there are two methods to convert search keywords into wordid in generator paralleling, namely, quasi synchronous paralleling method and self synchronous paralleling method. At present, quasi synchronous parallel method is widely used. Quasi synchronous parallel method is divided into manual, semi-automatic and automatic. Generally, manual or semi-automatic operation methods are adopted. At present, we use the manual quasi synchronous parallel method, and the specific operating procedures are as follows:

1 After the generator step-up operation is normal, it is necessary to turn the synchronization switch (5kp "tie line synchronization switch" tk/or 6kp "generator synchronization switch" TK) of the synchronization point to be paralleled to the right to the "on" position according to the specific operating conditions of the generator and the power system, so as to make the synchronization bus live

    2. Set the generator synchronization locking switch STK to the "locking" position, and its 1 and 3 contacts are disconnected. At the same time, the synchronization check relay TJJ enters the locking state

    3. Turn the 6kp "manual quasi synchronization switch" 1stk left to the "coarse adjustment" position, and the 6kp combined three-phase synchronization meter s has the indication of voltage and cycle. At this time, adjust the strain rate conditioning range (/s) 0 by adjusting the power generation 19 experiment The voltage and frequency of 0067 machine are similar to or basically consistent with the voltage and frequency of electricity

    4. When the difference between the generator cycle and the electric cycle is within 1.0 cycles/s, turn the "manual quasi synchronization switch" 1stk right to the "fine adjustment" position, then the coil of the combined three-phase synchronization meter s is powered on, and the pointer begins to rotate slowly clockwise. At this time, the frequency of the generator to be paralleled should be more finely adjusted according to the indication of voltage and frequency. In order to enable the generator to be paralleled to immediately carry part of the load, the frequency of the generator to be paralleled should be slightly greater than the frequency of the same period. At the same time, place the operating handle of the switch to be paralleled (121 of 5kp or 101 of 6kp) in the "ready for closing" position, and make preparations for parallel closing. At this time, the green indicator light of the switch flashes. When the pointer is close to the synchronization point (considering that the switch operating mechanism has an action time of about 0.2 seconds), quickly turn the operating handle of the standby switch (121 or 101) to the closing position. At this time, the red indicator light of the switch is flat and the green indicator light is off, which indicates that the standby generator is successfully paralleled

    5. After the generator is paralleled, the operating handles of the synchronization switch, manual quasi synchronization switch and synchronization locking switch on the control panel should be restored to their original positions, and then the load should be connected to make the generator operate in the normal operation mode

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