What are the power system voltage regulation methods and measures?
Power system voltage regulation
1.Shun pressure
The peak load allows a slightly lower voltage at the central point and a slightly higher voltage regulation at low load. It is suitable for distribution networks that allow for large voltage offsets, such as rural distribution networks.
2. Reverse pressure regulation
The voltage regulation method of lowering the voltage of the central point when the central point voltage and the low valley load are increased at the peak load. It is usually used when the power supply line is long and the load changes greatly.
3. Constant pressure regulation
The voltage regulation method that maintains the central point voltage at a substantially constant value under any load. It is usually applied to situations where the load variation is small and the voltage loss on the line is small.
Power system voltage regulation measures
1. Correctly select the ratio of the power transformer and the voltage tap
The rated voltage of the primary coil of the transformer should be reasonably selected. The user transformer close to the power supply can be used with 10.5kV or 6.3kV. The user transformer far from the power supply can use 10kV or 6kV to make the secondary voltage close to the rated value. Generally, the total range of the transformer high-voltage side voltage tap can be adjusted to 10%, manufactured by ±5%, ±2×2.5% or +0%, -2×5%, etc., using voltage taps to change the transformer ratio and adjust The secondary coil voltage ensures that the terminal voltage of the powered device does not exceed the allowable value.
2. Reasonably reduce the impedance of the power supply and distribution system
System impedance is one of the main factors causing voltage offset. Reasonable selection of wires and cross-sections to reduce system impedance can keep the voltage level relatively stable under load fluctuations. Since the reactance of the high-voltage cable is much smaller than that of the overhead line, the cable line should be used when conditions permit.
3. Balance the three-phase load
In the design and power management, the three-phase load should be balanced as much as possible, and the uneven distribution of the three-phase load will generate an unbalanced voltage, thereby increasing the voltage offset.
4. Reasonably adjust the operation mode of the power supply system
For enterprises with one-shift or two-shift production, the load is large during the work shift, and the voltage is often low. At this time, the tap of the high-voltage winding of the power supply transformer can be set at -5%, in order to prevent it during non-work shifts. If the voltage is too high, some transformers can be cut off and the low voltage tie line can be used for power supply. For the substation where two main transformers are running in parallel, when one load is light, one transformer can be cut off, which can also reduce the overvoltage and can The economic operation of the transformer is considered comprehensively.
5, using reactive power compensation device
Due to the large inductive load of the user, the power supply system generates a large amount of reactive power with phase lag, reduces the power factor, and increases the voltage drop of the system. The parallel capacitor method can generate the reactive power of the phase lead, which reduces the power in the line. Reactive power transfer reduces the voltage drop of the system.
6, using on-load tap changer
The on-load tap-changer can realize effective load-bearing voltage regulation according to the load fluctuation and the actual level of the power supply voltage. It has great technical advantages, but it is generally only applied to large-scale hub substations. The voltage offset of most users in an area is in compliance. For important loads with high voltage quality requirements, consider setting up a small on-load tap-changer for local voltage regulation.
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