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ZGPT Semi-automatic/Full-automatic Parallel Operation for MTU, Cumins, Perkins, Doosan Diesel generator
I. Parallel theory
The set in parallel means that several generator sets are in operation, the power provided by each generator set is connected to a single power to load. Every set should meet the four conditions as same phase-sequence, same voltage, same frequency as well as same phase-position, when can parallel to the whole system safely.
The important problem is to share loads appropriately when the multi gensets (different brands and types) are in parallel operation. The load is composed by active power (kW) and reactive power (KVA). The active power is provided by diesel speed regulating system, and reactive power provided by generator AVR.
II. The concept of parallel cabinet
The optimum operating state is between 70% and 85% of load. If generator sets continue to operate beyond this load range for a long time, it will not only cause waste of energy, but also increase the combustion waste, which needs to supply frequent maintenance.
When the load and load variation become bigger, several sets supply electricity separately, some load of sets is very small, while some load is very big. In order to start the electro-motor, we will increase the capacity and make set in the condition of light load. This has many faults of enormous waste energy, hard management, many times of maintenance and high frequency, making no full use of the existing resource.
The advantages of parallel system: enhance quality and capacity of electricity, enhance the reliability of system, and increase the capability of directly starting asynchronous motor. With flexible system operation, reasonable load share as well as simplified supplying system grounding, it will make sets operate in economic loading condition and reduce the expense of operation and maintenance.
ZGPT Semi-automatic Parallel Operation
1. Features
1.1 Optimizing selection for components, safe and reliable, easy maintenance.
1.2 Centralized parallel operation, easy and convenient operation.
1.3 Excellent performance and price.
2. Composition
2.1 Main switch
The domestic famous air circuit breaker or joint, import and user-defined air circuit breaker is adopted as the executive components of completing operation with functions of overload, over-current protection and pre-accumulator.
2.2 Measurement meter
Adopting 6L2 series meters as the display of the set operation status and parallel operation.
2.3 Synchronizer
Complete the manual and semi-automatic parallel function. Rotated speed or voltage regulation resistance shares the active power and reactive power of system in parallel operation.
2.4 Protection device
Protections of reverse power, overload and over-current.
2.5 Control system
Adopting relay and change-over switch as logic control components, easy maintenance.
3. Main technological parameters
3.1 Work conditions: Specification of diesel generator set.
3.2 Generator major loop
Rated voltage�?00/230V
Rated current�?.804×set power（kW�?/DIV>
Rated frequency�?0Hz
Power factor�?.8
3.3 About diesel generator set of same power, the division difference of active power and reactive power is not more than 10% in parallel operation. However, about diesel generator set of different power, the division difference of active power and reactive power for high-powered genset is not more than 10% in parallel operation, while the division difference for low-powered genset is not more than 20%. About semi-automatic parallel operation, the power ratio of single genset is not in excess of 3:1.
4. Functional description
The parallel control cabinet can be installed with parameter meter and synchronizer, as AC voltage, current, frequency and power. And the parallel cabinet can separately complete the operations of manual close, open, alarm reset and automatic synchronous close.
5. Parallel figure
ZGPT Full-automatic Parallel Operation
When two or more gensets are in parallel, the set is initiated automatically (The set must be self-start set.), once the start control signal is received (This signal can be provided by manual or external controller.). After the start, the control system will complete parallel operation automatically. The load is shared automatically in parallel. The set can be increased or reduced automatically according to the load, in order to achieve non-impulse load transfer. When the stop signal is received, the system will be disconnected automatically as follows: firstly, reduce the load gradually, the set is in parallel operation as load is near zero; then the set is disconnected and withdrawn from operation. After then, the set is shutdown after the idle operation for minutes. The operation sequence is also designed by requirements.
1. Features
1.1 Optimizing selection for components, safe and reliable, easy maintenance.
1.2 Centralized parallel operation, easy and convenient operation.
1.3 Excellent performance and price.
2. Composition
2.1 Main switch
The domestic famous air circuit breaker or joint, import and user-defined air circuit breaker is adopted as the executive components of completing operation with functions of overload, over-current protection and pre-accumulator.
2.2 Measurement meter
Adopting 42L6 series meters as the display of the set operation status and parallel operation.
2.3 Synchronizer and load shares
The American GAC parallel control module is adopted, in order to finish the automatic and manual parallel function and automatic load shares proportionally.
2.4 Protection device and alarm display
Protections of reverse power, overload and over-current.
2.5 Control system
Adopting relay and general change-over switch as operating control components, easy maintenance, and the PLC as logic control components.
3. Main technological parameters
3.1 Work conditions: Specification of diesel generator set.
3.2 Generator major loop
Rated voltage�?00/230V
Rated current�?.804×power （kW�?/DIV>
Rated frequency: 50Hz
Power factor�?.8
3.3 About diesel generator set of same power, the division difference of active power and reactive power is not more than 10% in parallel operation. However, about diesel generator set of different power, the division difference of active power and reactive power for high-powered genset is not more than 10% in parallel operation, while the division difference for low-powered genset is not more than 20%.
4. Functional description
The parallel control cabinet can be installed with parameter meter and synchronizer, as AC voltage, current, frequency and power. And the parallel cabinet can separately complete the operations of manual close, open, alarm reset and automatic synchronous close.
4.1 Automatic parallel: The synchronous module, based on the frequency and phase position of electrical power of bus-bar, can regulate the speed automatically. When the set reaches the synchronism point, the module gives the close signal automatically, with the whole process not more than 5S.
4.2 Automatic load sharing: According to power ratio for average load sharing after parallel operation, apply the isochronous automatic load sharing module, with full electricity, highly reactive sensitivity and high-adjusting accuracy. Share the total load averagely in proportion to size according to different powers. The automatic load sharing deviation can be controlled within 10% from idle load to overload. The PLD close-loop mode can increase the oil capacity advanced before the change of speed as the great load fluctuation; while the traditional regulating system may increase the oil capacity after the decline of speed (frequency) to make excellent performance of electric network.
4.3 Peak adjustment: The system automatically controls the numbers of parallel sets according to the capacity of load, and makes the operation of set better economy. If customer needed, we can provide pre-start function. When the system has standby set and needs to start the high-capacity motor load, we can provide the signal to start and parallel the standby sets, reduce the impact to system as starting the motor. (The emergency supply-electricity generator set system doesn’t set up this function)
4.4 The soft over\unloading and zero-power open: The load transfer of sets is not transient transfer in the peak regulating function, because the transient transfer will cause voltage fluctuation to the whole parallel system and impact to set and load. Applying the soft over\unloading, the whole system has no impact in the transfer process with the load transfer according to certain slope. When needs to remove a set, it will make the soft load wholly transfer to other sets, then the set could separate brakes automatically. In the same way, a set after parallel operation is loaded in the given slope, making the distribution and 100% load of same powered sets.
4.5. Protection
When the engine or control system go wrong in operation (as obstruction of engine fuel ), it will cause the abnormal power, then other set will make them enter motor condition, which increase the load of system. At the time, the control system will break the set automatically and give the alarm.
When the load appears over-current protection, system will trip automatically; break the supplying power as well as automatic cooled shutdown at the same time. While removing the malfunction, system will provide electrical power with automatic operation without recovery of the city electricity. Please connect with us for special needs.
4.6. Fault display and inter-trip. If the set shutdown in operation because of the problem for high water temperature, the parallel switch will be inter-trip to prevent reverse power to drag other sets and prevent the high pulse from burning excitation system. The malfunction indicator will work during this protection.
4.7. ATS transfer function (optional): The system monitors mains supply automatically. When the mains supply fails, the start can be delayed and paralleled automatically. After parallel, ATS can provide load transfer signal automatically and the load is transferred to genset. While the mains supply is recovered, the auto delay timer will transfer load to mains supply. Then, the parallel set will be open automatically and be shutdown for cooling, ready for next start.
5. Transfer System Diagram
Parameters:
·three-phase wire voltage
·three-phase current
·frequency
·active power
·power factor
·active watt-hour meter
·reactive watt-hour meter
Protections:
·high generator voltage
·low generator voltage
·generator overload
·generator short circuit
·reverse power
·power leakage protection (optional)
Indications:
·generator fault
·high generator voltage
·low generator voltage
·reverse power
·emergency stop
·air switch close
·generator operation
The main components list about automatic parallel operation:
|
Components |
Specification |
Product base |
|
main switch |
By the set |
Import\Joint |
|
Automatic synchronizer |
GAC SYC6714 |
Import |
|
Automatic load share protector |
GAC LSM672 |
Import |
|
Three-phase indicator |
200VAC |
Optional |
|
Three-phase current meter |
By the set |
Optional |
|
Voltage meter |
0-500V |
Optional |
|
Power meter |
By the set |
Optional |
|
Frequency meter |
45-55HZ220VAC |
Optional |
|
Power factor meter |
N/A |
Optional |
|
Three-phase voltage option switch |
N/A |
Optional |
|
Auto\Manual start switch |
N/A |
Optional |
|
Indicator |
24V DC |
Optional |
|
Alarm |
24V DC |
Optional |
|
Emergency button |
N/A |
Optional |
|
Synchronizer |
N/A |
Optional |
|
Synchronizer switch |
N/A |
Optional |
|
Relay |
N/A |
Optional |
|
Transformer |
N/A |
Optional |
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