二．什么叫发电机组的准同期并列法？怎样进行同期并列？准同期就是准确周期。用准同期法进行并列操作，发电机组电压必须相同，频率相同以及相位一致，这可通过装在同期盘上的两块电压表、两块频率表以及同期表和非同期指示灯来监视，并列操作步骤如下：
将其中一台发电机组的负荷开关合上，将电压送至母线上，而另一台机组处在待并状态。合上同期开头，调节待并发电机组的转速，使它等于或接近同步转速（与另一台机组的频率相差在半个周波以内），调节待并发电机组的电压，使其与另一台发电机组电压接近，在频率与电压均相近时，同期表的旋转速度是越来越慢的，同期指示灯也时亮时暗；当待并机组与另一台机组相位相同时，同期表指针指示向上方正中间位置，同期灯最暗，当待并机组与另一台机组相位差最大时，同期表指向下方正中位置，此时同期灯最亮，当同期表指针按顺时针方向旋转时，这说明待并发电机的频率比另一台机组的频率高，应降低待并发电机组的转速，反之当同期表指针按逆时针方向旋转时，应增加待并发电机组的转速。当同期表指针顺时针方向缓慢旋转，指针接近同期点时，立即将待并机组的断路器合闸，使两台发电机组并列。并列后切除同期表开关和相关的同期开关。
三．在进行发电机组的准同期并列时，应注意什么？准同期并列是手动操作，操作是否顺利与运行人员的经验有很大的关系，为防止不同期并列，下列三种情况不准合闸。1． 当同期表指针出现跳动现象时，不准合闸，因为同期表内部可能有卡带现象，反映不出正确的并列条件。 2． 当同期表旋转过快时，说明待并发电机组与另一台发电机 组的频率相差太大，由于断路器的合闸时间难以掌握，往往使断路器不在同期点合闸，所以此时不准合闸。3． 如果同期表指针停在同期点上不动，止时不准合闸。这是因为断路器在合闸过程中如果其中一台发电机组的频率突然变动，就有可能使断路器正好合在非同期点上。
四．怎样调整并列机组的逆功现象？
当两台发电机组空载并列后，会在两台机组之间，产生一个频率差与电压差的问题。并且在两台机组的监视仪表上（电流表、功率表、功率因数表），反应出实际的逆功情况，一种是转速（频率）不一致造成的逆功，另一种是电压不等造成的逆功，其调整如下：
1．频率造成逆功现象的调整： 如果两台机组的频率不等，相差较大时，在仪表上（电流表、功
表）显示出，转速高的机组电流显示正值，功率表指示为正功率，反之，电流指示负值，功率指示负值。这时调整其中一台机组的转速（频率），视功率表的指示进行调整，把功率表的指示调整为零即可。使两台机组的功率指示均为零，这样两台机的转速（频率）基本上一致。但是，这时电流表仍有指示时，这就是电压差造成的逆功现象了。
2,电压差造成逆功现象的调整： 当两台机组的功率表指示均为零时，而电流表仍然有电流指示（即一反一正指示）时，可调整其中一台发电机组的电压调整旋钮，调整时，视电流表与功率因数的指示进行。将电流表的指示消除（即调整为零），电流表无指示后，这时视功率因数表的指示，把功率因数调至滞后0.5以上即可.一般可调整至0.8左右,为最佳状态。
五、发电机保护回路
1．逆功 逆功现象是由发电机组转速（频率）及电压不同而造成的，即一台发电机组带正功，而另一台机组带负功率。也就是说带负功率的机组，这时变成了一个负载（此机组频率低，转速不一致的现象）。电压不相同时，电压高的机组，向电压低的机组，提供一个无功电流与无功电压（此机组的电流表正向指示），相当于在本供电系统内，加了一个调相机组。电压低的机组，这时成为一个大的负载，接受一个很大的无功电流，来维持两台机组的电压平衡（此机组的电流表反向指示）。监测时把某一台机组的电压调高，或将另一台机组电压高低，造成一台机组有逆功电流，其动作电流为额定电流20%左右。逆动继电器动作、跳闸、报警，但不停机。
2．过电流： 现在的发电机组额定功率一定的，它的超载能力很低，基本上在额定功率的5%左右，允许带载时间15~30分钟，最多不超60分钟，超过这个时间，发电机组会发热，导线绝缘会降低，也就降低了使用寿命。所以在设定过电流保护时无特殊要求的，过电流保护设定在额定电流的110%即可。带载测试时，将电流带至额定流的110%，过流继电器动作。跳闸、报警、不停机。
3．过电压： 在并列使用发电机组时最怕供电系统发生振荡，一但发生振荡系统电压升高，易造成用电设备及供电设备的绝缘击穿，使供电设备与用电设备一起瘫痪。为此并列使用的发电机组均装有过电压保护，其设定值为额定电压的105%为最佳。短接过电压继电器，跳闸停机、报警动作 .
六、分合闸回路分、合闸回路均接入手机并列，自动并列的控制回路。
1． 手动分合闸：每台机组均可做为首机或待并分、合闸使用，在手动并车或供电时，使用手动分合闸。
2． 自动分合闸：每台机组均可选择为待并机组，或首台机组；首机机组自启动后，合闸回路自动合闸，自动投入及退出同期。同期后把待并机组自动合闸并列运行。
3． 无论是手动合闸，还是自动合闸，一旦机组出现逆功，过了低油压、高水温、高水温、高油温、过电压，全部自动分闸解列与负载脱离。
七、同期回路
1． 当首机合闸后把电源送至母线，这时母线检测同期回路，与待并机的同期回路，接到信号后，自动合上同期检测继电器。将母线电压与待并机电压送至同期控制模块，模块自动检测，并列机组的电压与转速。如果转速有差别时，同期模块自动调整待并机转速，使其达到并列条件。找到同期点后同期模块发出合闸指令，待并机组接到指令后执行合闸，即两台机组并列运行。
2． 机组并列后，同期回路自动退出工作状态，但必须人为的把自动同期的转换开关退出，防止来电后在解列时，待并机组又接到并列信号，将同期装置自动投入，使机组再次并列。
八、负载分配
1． 单机运行时，负载分配器不投入工作。
2． 机组并列后每台机组的负载分配器，同时投入工作，各自调整自已的转速，使其两台机组的功率平均分配，其工作原理，就是根据本机组的输出功率的大小（即电流的大小），自动调整丁机组的转速，使其负载平
九、电压调整回路
1． 机组并列前，必须把两台机组的电压调整在同一数值上。
2． 空载并列后，调整电压旋钮，把逆功现象消除，使其功率因数在滞后0.8左右即可。
3． 并列机组带载后，可根据负载情况，手动调节电压调整旋钮，使其功率因数在最佳位置，以后可不用再调整。
十、速度调整回路
1． 并列前必须把两机组的速度（频率）调整一致。
2． 并列时，可根据同期表的转动速度，调节首机或待并机组的转速，使同期表转动方向，按顺时针或逆时针方向转动，速度越慢越好，但同期表的指针必须转动才能并列。
3． 并列后，观察两台机组的电流、功率是否平衡，如差别太大，可调整速度旋钮，将两台机组的功率
十一、仪表检测回路
1． 操作前，必须把各种相关的仪表调改至零，但功率因数表与频率表不在零处。
2． 操作时，观察各种仪表的运行状态，是否符合规定（有无仪表接线接反的现象）。
3． 电流、电压、要使用有关仪表与之检验一下，看指示数值是否正常。
十二、启动回路
1． 操作前必须首先检查启动回路是否正常。
2． 启动后相关元件是否能够正常工作。
3． 启动机与主机的结合是否正常，能否退出。
十三、停机回路
1． 停机电磁铁与电磁阀动作是否可靠。
2． 在机组发生故障时，是否自动停机。
3． 手动停机回路是否完善。
4． 只需跳闸时，是否停机等现象。
Conditions and working principle of diesel generators and machine grid
Diesel generator set and control
A. What are the conditions of parallel operation of generator sets? Generating units put into parallel operation of the whole process is called parallel. A generator set up and running, the voltage sent to the bus after the start of another generating units with a generating set side by side in the closing moments, the current generator set should not be a harmful impact, the shaft not subject to sudden impact. After closing, the rotor should be able to quickly pulled into synchronization. (Ie, the rotor speed is equal to the rated speed) generator group tied for the RMS and waveform of a generator set voltage must meet the following conditions must be the same the same. Two generator voltage phase 3. Two generating units at the same frequency. (4) the phase sequence of the two generating units.
Two. What is the quasi-synchronization of the generator set side by side? How Juxtaposition? The quasi-synchronization is accurate cycle. Quasi-synchronization method for parallel operation, the generator set voltage must be the same, the same frequency and phase-coherent two voltmeter mounted on the plate of the same period, two frequency table and the same period in the table and asynchronous indicator to monitor the parallel operation as follows:
One of the generating units of the load switch is closed, the voltage sent to the bus, while the other units in the pending and status. Close on the same period in the beginning of adjustment to be the speed of the generator set, making it equal to or close to synchronous speed (with another unit, the frequency difference of less than half a cycle), regulating the voltage to be generating sets to make it with another voltage of the generator set close in frequency and voltage are similar to the same period in the table rotation speed is getting slower and slower over the same period indicator light and dark; be and the unit with another unit phase, the table pointer over the same period indicate upward Founder intermediate position, the same period in the light most dark, the maximum phase difference with another unit when the unit be and the same period in the table point to a location under the Founder, the same period in light of the brightest, when the same period in the table pointer clockwise This shows that to be and the generator frequency is higher than the frequency of the other units, should reduce the wait and the speed of the generator sets to be and the speed of the generator set should be increased, and vice versa when the same period in the table pointer by counterclockwise rotation. When table pointer over the same period the slow clockwise rotation, the pointer close to the point of the same period, immediately will be the unit circuit breaker closing, the two units side by side. Tied after the removal of the same period in the table switch and switch of the same period.
Three. During the quasi-synchronization of the generator set side by side, attention should be what? Quasi-synchronous tie manual operation, operating smoothly and the experience of the operating personnel have a great relationship, in order to prevent different period tied, the following three conditions are not allowed to switch on. A. When the same period in the table pointer jumps are not allowed to switch on, because within the same period in the table may have a cassette, and do not reflect the correct parallel conditions. Two. When rapid table rotation during the same period, indicating that much difference, be and the frequency of the generator sets and other generating units often the breaker is not in the same period in point of closing the circuit breaker closing time is difficult to grasp, so in this case are not allowed to closing. 3. Table pointer over the same period parked in the same period point does not move, only when you are not allowed to switch on. This is because the circuit breaker in the closing process, if one generating units at the frequency of sudden changes in circuit breaker, it is possible to make precisely in the asynchronous point.
Four. How to adjust the parallel phenomenon of reverse power unit?
When the two units empty tied, resulting in a poor frequency and voltage difference between the two units. And monitoring of the two units on the meter (ammeter, power meter, power factor meters), reflect the actual reverse power, a speed (frequency) is inconsistent reverse power, another is a voltage ranging from causing reverse power, adjusted as follows:
A. Frequency caused by the phenomenon of reverse power adjustment: If the two units of frequency range, the difference is large, on the meter (ammeter, power
Table) show, the show coincided with the high speed of the unit current, and power meter indicates a positive power, on the contrary, the current directions negative power indicate negative values. Then adjust the speed of one unit (frequency), depending on the power meter instructions to adjust to the instructions of the power meter adjusted to zero can be. Two units of power directions are zero, so the speed (frequency) of the two machines are basically the same. However, when the ammeter still indicate, this is the voltage difference caused by the reverse power phenomenon.
2, the voltage difference caused by the phenomenon of reverse power adjustment: When the power meter indication of the two units are zero, while the ammeter current instructions (ie a reversal of a positive indication), adjust the voltage of the generator sets to adjust knob adjustment, depending on the ammeter with the instructions of the Power Factor. Ammeter's instructions to eliminate (ie adjusted to zero), no indication ammeter, then the instructions in the table of power factor, lagging power factor to more than 0.5 can be adjusted to 0.8, the best state.
Generator protection circuit 1. The inverse function inverse function phenomenon is caused by the speed (frequency) and the voltage of the generator set, generating units with a positive work
While the other unit with negative power. In other words with a negative power of the unit, then become a load (low frequency of this unit, the speed of inconsistency). Voltage is not the same, the high voltage of the unit low voltage unit, a reactive current and reactive power and voltage (this unit ammeter positive indication), which is equivalent to the power supply system, plus a phase modulation unit . Low voltage of the unit, then become a big load, to accept a large reactive current to maintain the voltage balance of the two units (this unit the ammeter reverse directions). Monitoring to increase the voltage of a unit or another unit voltage level, resulting in a unit with inverse reactive current, the operating current for
Two. Over current: now the generator set power rating certain, the overload capacity is very low, basically allowed to load in
3. Over-voltage: tied to use of the generator sets are most afraid of the power system oscillations, but the occurrence of the oscillation system voltage increases, could easily lead to the breakdown of insulation of electrical equipment and power equipment, power supply equipment and electrical equipment with paralysis . Used for this parallel generator sets are equipped with overvoltage protection, 105% of rated voltage set value for the best. Short take over voltage relay, trip down, the alarm action.
(F) and closing the loop points, closing the loop are connected to mobile phones side by side, the automatic control loop in parallel. A. Of opening and closing manually: each unit can be done, led by machine or to be opening and closing to use in the manual car or power of opening and closing manually.
Two. Of opening and closing automatically: each unit can choose to be and crew, or the first unit; since the launch of the first machine unit, the closing loop of the automatic switch on, automatic input and exit the same period. Over the same period after the wait and the unit automatically closing in parallel operation.
3. Manual closing or automatic closing, once the unit is the reverse power, over a low oil pressure, high temperature, high temperature, high oil temperature, over-voltage, all automatic gate splitting and load out.
(7) In the same loop. Power after the closing of the first machine sent to the bus when the bus detection of synchronous circuit, be and the machine synchronous circuit, the received signal, automatically close synchronism check relay. Sent to the same period the voltage of the bus voltage to be and machine control module, the module automatically detects the voltage and speed of the parallel units. If the speed difference, the same period in module automatically adjusts to be and machine speed to reach the parallel conditions. Issue closing instructions to find the same period point over the same period module be and crew received instructions executed after the closing of two units in parallel operation.
Two. Units side by side, the synchronous circuit automatically withdraw from the work state, but it must be man-made automatically over the same period of the changeover switch to exit, to prevent calls after splitting, to be and the unit also received parallel signal synchronizing device automatically put into the unit once again side by side .
(H) The load distribution 1. Stand-alone runtime, load distributor does not work.
Two. Units side by side, each unit of the load distributor, at the same time to work, each to adjust their own speed, two units of power evenly distributed, the size of its working principle is based on the size of the output power of this unit (ie, current) to automatically adjust the speed of the small units to make it load level
(Ix) the voltage regulation loop
A. Units side by side before, the voltage of the two units must be adjusted at the same value.
Two. No-load side by side, to adjust the voltage knob to eliminate the phenomenon of reverse power, power factor can lag 0.8.
3. Tied to the unit load, depending on the load situation, manually adjust the voltage adjustment knob, so that power factor in the best
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