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Uniform distribution of load power among gasoline generator sets in Shanghai
The parallel connection of Shanghai gasoline generating units should first meet the requirements for even distribution of power. The even distribution of power includes both active power and reactive power. Uniform distribution refers to the fact that the active power and reactive power carried by each generator should be proportional to their rated power.
There are definite requirements for the power distribution of the parallel operation generator sets in China. When the AC generator sets are operated in parallel, when the load changes within the range of 20% to 100% of the total rated power, it should be able to operate stably, and its power distribution error should be consistent. The following requirements: 1 The difference between the actual power actually assumed by each generator and the calculated value distributed according to the ratio of the rated power shall not exceed ±10% of the rated active power of the generator when the rated power of the generator is the same; when the rated power of the generator At the same time, it shall not exceed 110% of the maximum rated generator active power and ±20% of the rated generator rated active power; 1 The actual value of the reactive power assumed by each generator and the calculated value distributed according to the rated power of the generator. Poor, should not exceed ±10% of the maximum rated reactive power of the generator.
If there is a large imbalance in power distribution, whether it is active power or reactive power, it will not only affect the efficiency and economy of the unit operation, but can even cause the failure of the entire power plant.
If the active power distribution of the parallel-connected generator sets is seriously unbalanced, when the total power of the load is large, a generator set is often full or overloaded, while the other generator is still in a light load state, and thus cannot be fully utilized. The capacity of the gensets exerts the efficiency of the entire plant. Overloading of the unit will not only cause harm to the gasoline engine or generator, but also will cause the protection equipment to move and affect the operation of the entire power plant. Conversely, when the total power of the load is very small, the imbalance of active power often causes active circulation between the generator sets, causing some of the units to turn into motor states, which is also not allowed for gasoline engines. When the unit has reverse power protection, the reverse work phenomenon will cause reverse work trip and cause failure. For the gasoline engine power station with frequent changes in the load and a wide range of changes, the above situation should attract more attention. For example, in a petrol power plant of a marine electric propulsion device, when the parallel generators have uneven distribution of active load, when the ship is sailing at full speed, the total load power is large, overloading the heavy-duty generator is often caused, causing the switch to trip, resulting in the original light load. The generator was suddenly overloaded and the switch tripped, causing a serious power failure. When the ship is docked at the dock, the light load generator enters the reverse power state due to the small total load, causing reverse work tripping, which affects the reliability of the power plant and even the entire ship. The above conditions are sufficient to illustrate that the even distribution of power between parallel-connected generators is not only a problem of the economic operation of a generator, but also an important factor in ensuring the reliability of power supply for the entire gasoline engine power station.
Non-uniform distribution of reactive power, although not a serious impact on the gasoline engine, but the generator power rating is determined based on the apparent power, reactive power imbalance, will inevitably cause the apparent power of the generator imbalance, the same It will limit the capacity of the generator set, especially for power plants with low power factor, the load capacity of the set does not depend on the rated power of the gasoline engine, but depends on the size of the generator's rated current. Shanghai Gasoline Generator
The unbalanced reactive load can also be viewed as an imbalance between the two generators. The flow, and sometimes this current exceeds the load current of the generator, generates additional losses inside the generator. Even overloaded the generator. Reactive overcurrent also trips the generator's main switch, causing a fault. In addition, the size of the generator reactive current is consistent with its excitation current. The imbalance of reactive current is often at the same time as the excitation current imbalance, causing the excitation system to overload or even fail, such as the generator rotor winding is burned. The rectifier diode of the compound excitation device is damaged, and the consequences of such failure are often quite serious. It can be seen that the even distribution of reactive loads and the even distribution of active loads have the same meaning. As for the factors affecting the even distribution of load and adjustment methods, they will be discussed in detail later.