Preconditions and technical solutions for diesel generator parallel operation
With the development and growth of the country, many well-known domestic enterprises have higher and higher requirements for equipment, but they are also often accompanied by the trouble of power outages. How did they solve it? At present, many enterprises in our country will install a diesel generator when solving the power outage, so as to solve the trouble of power outage. However, due to the advanced equipment and the relatively high power of the equipment, when a diesel generator set cannot provide sufficient power, the following is the use of diesel generator sets and technology. What should be paid attention to when using diesel generator sets in parallel Matters, what conditions to meet, and technical solutions for paralleling.
The following is a brief description of the diesel generator parallel technology solution by Jiangsu Lide Power Equipment Co., Ltd.
并列运行的条件是什么？ What are the conditions for generating units to run in parallel?
The whole process of generating units running in parallel is called parallel. Run one generator set first and send the voltage to the bus. After the other generator set is started, it should be placed in parallel with the previous one. At the moment of closing, the generator set should not cause harmful surge current, and the shaft No sudden shock. After closing, the rotor should be able to be pulled in quickly. (That is, the rotor speed is equal to the rated speed) Therefore, the gensets must have the following conditions:
The rms voltage and waveform of the generator set must be the same.
The phases of the two generator voltages are the same.
Both generators have the same frequency.
The phase sequence of the two generators is the same.
What is the quasi-synchronous juxtaposition method for generating units? How to carry out the simultaneous parallel?
The quasi-synchronous period is the exact period. For quasi-synchronous method for parallel operation, the generator set voltage must be the same, the frequency is the same, and the phase is the same. This can be monitored by two voltmeters, two frequency meters, synchronizers and non-synchronous indicators installed on the synchronizer disk. Proceed as follows:
Close the load switch of one of the generating units and send the voltage to the bus, while the other unit is in the standby state. Close the beginning of the same period, adjust the speed of the generator to be paralleled to be equal to or close to the synchronous speed (with a frequency difference of less than half a cycle from the frequency of the other generator), and adjust the voltage of the generator to be synchronized with the other generator. The voltage of the generator set is close. When the frequency and voltage are close, the rotation speed of the synchronization table is getting slower and slower, and the synchronization indicator is also on and off. When the standby unit is in the same phase as the other unit, the synchronization table pointer The indicator is at the upper and middle position. The synchronization lamp is the darkest. When the phase difference between the standby unit and the other unit is the largest, the synchronization table points to the lower center position. At this time, the synchronization lamp is the brightest. When the synchronization table pointer rotates clockwise This indicates that the frequency of the generator to be merged is higher than the frequency of the other generator, and the speed of the generator to be merged should be reduced. Conversely, when the pointer of the synchronization table rotates counterclockwise, the speed of the generator to be merged should be increased. When the pointer of the synchronization table rotates slowly clockwise and the pointer is close to the synchronization point, the circuit breakers of the units to be paralleled are closed immediately, so that the two generator sets are juxtaposed. After the juxtaposition, the synchronizer switch and the related synchronizer switch are removed.
What should be noticed when quasi-synchronous juxtaposition of generator sets?
The quasi-synchronous juxtaposition is a manual operation. Whether the operation is smooth or not has a great relationship with the experience of the operating personnel. To prevent the juxtaposition in different periods, the following three situations are not allowed to close.
1. When the pointer of the synchronization table appears to be beating, it is not allowed to close, because there may be a jam phenomenon inside the synchronization table, which does not reflect the correct parallel conditions.
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。 2. When the synchronization table rotates too fast, it means that the frequency difference between the standby generator set and another generator set is too large. Because the closing time of the circuit breaker is difficult to grasp, the circuit breaker is often not closed at the synchronization point. Do not close at any time.
3. If the pointer of the synchronization table stops at the synchronization point, it is not allowed to close at any time. This is because if the frequency of one of the generator sets suddenly changes during the closing of the circuit breaker, it is possible to make the circuit breaker close to the non-synchronous point.
How to adjust the reverse power phenomenon of parallel units? When two generators are side-by-side without load, a problem of frequency difference and voltage difference will occur between the two units. And on the monitoring instruments of two units (ammeter, power meter, power factor meter), the actual reverse power situation is reflected, one is the reverse power caused by the inconsistent speed (frequency), and the other is caused by the unequal voltage. Reverse power, its adjustment is as follows:
1. Adjustment of frequency causing reverse work phenomenon:
If the frequency of the two units is not the same, when the difference is large, it will be displayed on the instrument (ammeter, power meter). The current of the unit with a high speed will show a positive value, the power meter indicates positive power, otherwise, the current indicates a negative value, power. Indicates a negative value. At this time, adjust the speed (frequency) of one of the units, adjust it according to the indication of the power meter, and adjust the indication of the power meter to zero. Make the power indication of both units zero, so that the speed (frequency) of the two units is basically the same. However, at this time when the ammeter still indicates, this is the reverse power phenomenon caused by the voltage difference.
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。 2. Adjustment of reverse power phenomenon caused by voltage difference: When the power meter indications of both units are zero, and the ammeter still has current indication (that is, one inversion and one positive indication), the voltage adjustment of one of the generator sets can be adjusted. The knob, when adjusting, depends on the indication of the ammeter and power factor. Eliminate the indication of the ammeter (that is, adjust it to zero). After the ammeter has no indication, depending on the indication of the power factor meter, adjust the power factor to a lag of more than 0.5. Generally, it can be adjusted to about 0.8, which is the best state.
Generator protection circuit
1. Reverse power The reverse power phenomenon is caused by the different speed (frequency) and voltage of the generator set, that is, one generator set has positive power and the other set has negative power. In other words, the unit with negative power becomes a load (the frequency of the unit is low and the speed is inconsistent). When the voltages are not the same, the unit with a high voltage provides a reactive current and a reactive voltage to the unit with a low voltage (the unit's ammeter is positively indicating), which is equivalent to adding a camera unit in the power supply system. The low-voltage unit becomes a large load at this time, receiving a large reactive current to maintain the voltage balance of the two units (the unit's ammeter reversely indicates). During monitoring, the voltage of one unit is increased, or the voltage of the other unit is increased, resulting in reverse current of one unit, and its operating current is about 20% of the rated current. Reverse relay action, trip, alarm, but does not stop.
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。 2. Overcurrent: The current rated power of the generator set is fixed, and its overload capacity is very low, which is basically about 5% of the rated power . The allowed load time is 15-30 minutes, and the maximum is not more than 60 minutes. The generator set will generate heat and the insulation of the wires will decrease, which will reduce the service life. Therefore, there is no special requirement when setting the overcurrent protection, and the overcurrent protection can be set at 110% of the rated current. During the load test, the current is brought to 110% of the rated current, and the overcurrent relay is activated. Trip, alarm, non-stop.
3. Overvoltage: When using the generator set in parallel, the power supply system is most afraid of oscillation. Once the voltage of the oscillating system increases, it is easy to cause insulation breakdown of the power equipment and power supply equipment, and paralyze the power supply equipment and the power equipment. 105%为最佳。 To this end, the generator sets used in parallel are equipped with overvoltage protection, and the set value is 105% of the rated voltage is the best. Short circuit over voltage relay, trip and stop, alarm action.
(6) Opening and closing circuit Both the opening and closing circuit are connected to the mobile phone in parallel, and the control circuit is automatically connected in parallel.
Manual opening / closing: Each unit can be used as the first machine or waiting to be opened and closed, and closed, and when manually connected or powered, manual opening / closing is used.
Automatic opening and closing: Each unit can be selected as a standby unit or the first unit; after the first unit is started, the closing circuit is automatically closed, and the synchronization is automatically switched on and off. After the same period, the parallel units will automatically close and run in parallel.
Regardless of manual closing or automatic closing, once the unit has reverse power, after the low oil pressure, high water temperature, high water temperature, high oil temperature, and overvoltage, all the breakers will be automatically disconnected and disconnected from the load.
1. When the first machine is turned on, the power is sent to the bus. At this time, the bus detects the synchronous circuit and the synchronous circuit to be paralleled. After receiving the signal, it automatically closes the synchronous detection relay. The bus voltage and the voltage to be paralleled are sent to the synchronization control module, and the module automatically detects the voltage and speed of the parallel units. If there is a difference in rotation speed, the synchronization module automatically adjusts the rotation speed to be paralleled to make it parallel. After the synchronization point is found, the synchronization module issues a closing command. After the parallel unit receives the instruction, the closing command is executed, that is, the two units run side by side.
2. After the units are juxtaposed, the synchronization circuit automatically exits the working state, but the automatic synchronization transfer switch must be manually exited to prevent the parallel unit from receiving a parallel signal when it is dismissed after an incoming call, and the synchronizing device is automatically put into operation to make the units parallel again. .
(Eight) load distribution
1. When stand-alone operation, the load distributor is not put into operation.
2. After the units are juxtaposed, the load divider of each unit is put into operation at the same time, and each of them adjusts its own speed so that the power of the two units is evenly distributed. The working principle is based on the output power of the unit (that is, the current) , Automatically adjust the speed of the Ding unit to make it load balanced.
(9) Voltage adjustment circuit:
1. Before the units are juxtaposed, the voltage of the two units must be adjusted to the same value.
2. After paralleling with no load, adjust the voltage knob to eliminate the reverse power phenomenon and make its power factor lag around 0.8.
3． After the parallel units are under load, you can manually adjust the voltage adjustment knob according to the load to make the power factor at the optimal position, and you don't need to adjust it later.
(10) Speed adjustment circuit:
1. Before juxtaposition, the speed (frequency) of the two units must be adjusted to be the same.
2. When juxtaposed, the rotation speed of the first or standby unit can be adjusted according to the rotation speed of the synchronization table, so that the rotation direction of the synchronization table is rotated clockwise or counterclockwise. Tied.
3． After juxtaposition, observe whether the current and power of the two units are balanced. If the difference is too large, you can adjust the speed knob to adjust the power of the two units to be the same.
(11) Instrument detection circuit:
1. Before operation, all relevant instruments must be adjusted to zero, but the power factor meter and frequency meter are not at zero.
2. During operation, observe the running status of various instruments to see if they comply with the regulations (with or without reversed meter wiring).
3． Check the current and voltage with relevant instruments and see if the indicated values are normal.
(12) Starting circuit:
1. Before operation, you must check whether the starting circuit is normal.
2. Whether the related components can work normally after startup.
3． Whether the combination of the initiator and the host is normal and whether to exit.
(13) Shutdown circuit:
1. Whether the stop solenoid and solenoid valve operate reliably.
2. Whether to stop automatically when the unit fails.
3． Whether the manual stop loop is complete.
4． It only needs to be stopped when tripped.
是一家专业从事柴油发电机组、移动式柴油发电机组、集装箱式柴油发电机组、静音箱式柴油发电机组、康明斯柴油发电机组、玉柴柴油发电机组、沃尔沃柴油发电机组的生产厂家。 Jiangsu Reed Power Equipment Co., Ltd. is a professional manufacturer of diesel generator sets, mobile diesel generator sets, container diesel generator sets, silent box diesel generator sets, Cummins diesel generator sets, Yuchai diesel generator sets, and Volvo diesel generator sets . Manufacturer. (消音、水冷、空气净化及并机)、维修和零配件销售。 The company is mainly dedicated to the sales of diesel generator sets and mobile diesel generator sets, as well as ancillary projects (silencer, water cooling, air purification and paralleling), maintenance and spare parts sales of a series of products .
24小时服务热线，配备技术骨干，随时为客户排忧解难。 The company has a service team with rich maintenance experience and excellent technology. Each branch has set up a 24-hour service hotline, equipped with technical backbones, to solve problems for customers at any time. Rigorous, pragmatic, honest and responsible work attitude, and adhere to the customer-oriented, continuous innovation business philosophy, after years of continuous efforts, enjoy a high reputation among domestic counterparts.
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