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August 24, 2020
Operation Mode of Hydro-generator in Hydro Power Station
Operation mode of hydropower station turbine under rated conditions
1. The way that the turbine generator of a hydropower station operates according to the data specified on the manufacturer's nameplate is called the rated operation mode. The turbine generator of a hydropower station can operate continuously for a long time in this mode.
2. The rated value of the rotor current should be adopted when the rated power factor and voltage fluctuation are within ±5% of the rated value, and the frequency variation is within ±1%, so as to ensure the current value at the rated output of the generator.
3. After the turbine generator of the hydropower station is put into operation and before the temperature rise test, if there is no abnormal phenomenon, carry the load according to the nameplate data of the generator. Before the temperature rise test, the turbine generator of the hydropower station is not allowed to run beyond the rated value on the nameplate, and it is also not allowed to limit the capacity without basis. If the temperature rise test proves that the generator of the hydropower station has a large margin in terms of temperature rise, the analysis of the structure of the generator of the hydropower station also shows that when it can run beyond the rated value, the test record should be combined with the structure. Analysis (domestic products should be accompanied by the manufacturer’s opinions) after being submitted to the higher-level competent authority for approval, the rated value can be exceeded and operated with new data.
4. Generators with improved output must pass temperature rise tests and other necessary tests, as well as technical analysis and appraisal to determine the operating data after the increased output. After being approved by the higher-level competent authority, it can be used as the normal operation mode of hydropower generators. Excessive operation of hydro-generators in hydropower stations must consider whether the nameplate capacity of the prime mover (turbine), the excitation system of the hydropower station generators, related electrical (primary and secondary) equipment and mechanical ancillary equipment can be adapted.
5. The maximum temperature of the rotor winding, stator winding and stator core is the temperature of the hydroelectric power station turbine generator under the rated inlet air temperature and rated power factor, and the temperature that occurs during continuous operation with rated load. These temperatures are based on the temperature rise test. The result is determined, and its value should be within the limit allowed by the insulation class and the manufacturer.
6. When the maximum capacity is set on the nameplate of the hydroelectric generating set of the hydropower station, the hydropower station turbine shall be allowed to operate continuously and safely under the maximum load. The power factor at maximum load, the maximum operating current of the stator and rotor, and the temperature of each part of the generator shall be stated in the on-site operating regulations according to the manufacturer's regulations.
Operation mode when the inlet air temperature changes
1. Due to the influence of ambient temperature, when the inlet air temperature exceeds the rated value, if the temperature of the rotor winding, stator winding and stator core does not exceed the insulation class and the temperature allowed by the manufacturer after the test, the generator capacity may not be reduced. But when these temperatures exceed the allowable value, the stator and rotor currents should be reduced until the above allowable temperature is reached.
2. When the inlet air temperature is lower than the rated value, the stator and rotor currents can be increased until the winding temperature is within the range specified in Article 4.1.5.
3. If the generator has not been tested for temperature rise, when the inlet air temperature is higher or lower than the rated value, the allowable value of the stator current should be based on the allowable temperature of the stator winding and stator core given by the manufacturer.
4. For the temperature measurement of the stator core of the turbine generator of a hydropower station, when the inlet air temperature is lower than the rated value, the stator and rotor currents are allowed to increase until the inlet air temperature is 10°C lower than the rated value.
5. For air-cooled generators with closed cooling, the minimum inlet air temperature should be based on the non-condensing water droplets of the air cooler.
6. The temperature difference between the inlet and outlet air of the turbine generator of a hydropower station has increased significantly. The reasons should be analyzed and measures should be taken to solve the problem.
7. Each air cooler of the air-cooled generator must be equipped with temperature measuring components to facilitate the on-duty personnel to adjust the temperature of the cold air.
Operation mode when voltage, frequency and power factor change
1. Under the following conditions, the generator can be operated at rated capacity:
a) At rated speed and rated power factor, the deviation of the voltage from its rated value should not exceed ±5%.
b) At rated voltage, the deviation of frequency from its rated value shall not exceed ±1%.
c) When the voltage and frequency deviations at the same time (the two deviations do not exceed ±5% and ±1% respectively) and both are positive deviations, the sum of the two deviations does not exceed 6%; if the voltage and frequency are different, it is a positive deviation When the absolute value of the deviation between the two is not more than 5%. When the voltage and frequency deviation exceeds the above specified value, it should be able to run continuously. At this time, the output power is limited to the excitation current not exceeding the rated value and the stator current not exceeding 105% of the rated value.
2. The maximum allowable voltage for continuous operation of the generator shall comply with the manufacturer's regulations, but the maximum shall not be greater than 110% of the rated value. The minimum operating voltage of the generator should be determined according to the requirements of stable operation, and generally should not be lower than 90% of the rated value. If the generator voltage bus has a direct power distribution line, the operating voltage should still meet the user's voltage requirements. At this time, the stator current is limited to the rotor current not exceeding the rated value.
3. When the power factor of the turbine generator of a hydropower station changes during operation, the stator and rotor currents should not exceed the allowable value under the current inlet air temperature.
4. It is allowed to increase the active power of the generator to the rated apparent power operation by increasing the power factor, but it should meet the requirements of power grid stability.
5. Whether the generator can run in phase should follow the manufacturer's regulations. Anything not specified by the manufacturer shall be determined through special temperature rise test and stability check. The depth of the phase advance operation is determined by the heat generation of the end structural parts of the hydroelectric generator and the stability of the operation in the power grid.
6. The excitation current of the hydroelectric generators of hydropower stations that are allowed to operate as a regulator should not exceed the rated value during phase modulation operation.