What are the measures for voltage adjustment of the power system

The main measures are as follows:

1. Increase or decrease reactive power for voltage regulation, such as generators, condensers, shunt capacitors, and shunt reactors;

2. Change the distribution of active power and reactive power for voltage regulation, such as voltage regulating transformer and changing transformer tap voltage regulation;

3. Change the network parameters for voltage regulation, such as series capacitors, switching and stopping transformers running in parallel, and switching and stopping no-load or light-load high-voltage lines for voltage regulation.

Under special circumstances, the voltage is sometimes adjusted by adjusting the electrical load or curtailing.

The voltage regulation measures of the power system are:

1. Control and adjust the excitation current of the generator to change the voltage at the end of the generator.

2. Adjust the tap of the transformer to control the transformer ratio.

3. Reactive power compensation equipment is used in the substation to change the distribution of transmitted power.

4. Connect the capacitors in series on the transmission line to change the network parameters.

The power system is composed of power generation, transmission, distribution, electricity and other equipment and its auxiliary systems (relay protection, safety automation, measurement, dispatching automation and communication devices), according to the specified technical and economic requirements, to convert primary energy into electric energy and transmit and distribute it to users. The fundamental task of the power system is to provide users with sufficient, reliable, qualified and reasonable electric energy.

Power System Planning:

Electricity is a secondary energy source. The development of the power system should not only consider the resource conditions of primary energy, but also consider the situation of electric energy demand and related material and technical equipment, as well as the related economic conditions and indicators. In the total energy consumption of society, the proportion of electric energy has always been increasing.

The development of the information society has increased the dependence on electric energy.

In the United States, for example, the share of electricity in total energy consumption rose from 11% to 26% between 1920 and 1970, and will exceed 40% in the 90s. In order to meet the growing demand of users for electric energy, the power system must be developed on the basis of scientific planning.

The construction of the power system not only requires a large investment, but also takes a long time. Insufficient electric energy** or unreliable power supply will affect the development of the national economy, and even cause serious economic losses; Excess power generation, transmission and distribution capacity in turn means that the efficiency of power investment is reduced, which affects the cost of power generation. Therefore, it is necessary to carry out comprehensive planning of the power system to improve the predictability and scientificity of the development of the power system.

1. Transformer transformer.

The main function of the transformer is to convert the voltage and transmit electric energy, which can increase the voltage or decrease the voltage; According to different voltages and powers, transformers with different ratios and turns are wound. The output power can be very large, and it is commonly used to step down and boost in the larger power supply, which can isolate the primary power supply from the secondary load, which is beneficial to safety.

2. Resistance step-down.

This is a very common step-down method used in electronic circuits, which realizes voltage division and current limiting through series resistance; Shunt action is realized by parallel resistors; The voltage can be easily adjusted through the variable resistor, and the voltage can be regulated by both AC and DC; The disadvantage is that the resistor is an energy-dissipating element that generates heat, and the resistor with larger power is bulky.

3. Capacitor step-down.

The capacitor step-down function is innate, but now the manufacturing technology has developed by leaps and bounds, and the voltage resistance and capacity of the capacitor have been improved, the volume has been reduced, and the cost has been reduced, so it has been widely used. Through the current of the capacitor i=U XL, and the capacitive reactance xc=1 2 fc, it can be seen that the larger the capacitance of the capacitor, the smaller the capacitive reactance, and when the load such as resistance is connected in series with it, the capacitor plays the role of voltage divider.

4. Inductance step-down.

Inductor buck was applied relatively early, and the ballast on the fluorescent lamp we used was a typical buck inductor. In the electric fan, the governor is made of inductor taps; Its step-down principle is the same as that of the capacitor, and its inductive reactance XL=2 F, and there will be impedance and voltage drop when the alternating current passes; The filter inductor in the rectifier circuit actually acts as a step-down, reducing the AC component.

5. Thyristor voltage regulation.

This voltage regulation method can achieve stepless voltage regulation, and is widely used in DC motor speed regulation, lamp dimming and other circuits, including one-way thyristors and two-way thyristors, and the wiring mode is also very flexible and small in size; With the manufacture of high-power thyristors, the application is more extensive; The disadvantage is that the circuit is relatively complex; There are more components.

The measures to suppress the overvoltage of the power system are: (1) Improve the synchronicity of the switching action: Since many resonant overvoltages are caused by non-full-phase operating conditions, improving the synchronicity of the switching action and preventing non-full-phase operation can effectively prevent the occurrence of resonant overvoltage.

2) Install small reactance at the neutral point of the parallel high-voltage reactor: this measure can be used to block the power frequency voltage transmission and series resonance during non-full-phase operation.

3) Destroy the conditions for the generator to generate self-excitation and prevent the parameter resonance overvoltage.

4) Strictly implement the scheduling procedures: in the operation mode and the operation of the reverse gate.

In the process, the circuit breaker break capacitor is prevented from forming a series resonant loop with the no-load bus and bus PT to prevent the flutter from damaging the equipment due to resonant overvoltage.

5) Avoid operating overvoltage: when switching to the empty bus, strengthen the bus voltage monitoring, when ferromagnetic resonance occurs, the circuit breaker with broken capacitor should be closed immediately, the loop capacitance should be removed, and the resonance should be terminated to prevent the development of hidden dangers and accidents.

6) Neutral grounding point: increase the busbar to ground capacitance or reduce the voltage transformer in the system.

The number of grounding stations at the neutral point increases the ground inductive reactance of the busbar, thereby reducing the natural frequency of the natural vibration.

Eggplant skin avoids the ferromagnetic resonance overvoltage of the bus due to the east of the system.

7) Relay protection.

In view of the occurrence of specific accidents, such as single-phase grounding in the bus of the substation, the bus differential protection action, after the bus tie switch trips, if the main transformer switch acts before the line switch, it will not cause resonance.

1. Increase the reactive power for voltage regulation, such as generators, condensers, open-link capacitors, and shunt reactors.

2. Change the division of meritorious and reactive power into cities for suppression. Such as adjusting the compactor and changing the voltage regulation of the transformer tap.

3. Change the network parameters for voltage regulation, such as series capacitors, switching to stop the leaf train running transformer, dropping and stopping idling or dining high-voltage weft regulation.

According to the allowable deviation of the operating voltage, the voltage at the voltage pivot point is adjusted to the upper limit of the voltage curve during the peak load period of the power system, and the voltage is adjusted to the lower limit of the voltage curve during the trough load period.

When the power system is under peak load, the transmission power of transmission lines and transformers is large, and their voltage loss is also large, and the voltage at the user is low; At low valley loads, the transmission power of transmission lines and transformers is small, their voltage losses are also reduced, and the voltage at the user is high.

1. Control and adjust the excitation current of the generator to change the voltage at the end of the generator.

2. Adjust the tap of the transformer to control the transformer ratio.

3. Adopt reactive power compensation equipment in the substation to change the distribution of the transmission and shielding power.

4. Connect the capacitors in series on the transmission line to change the network parameters.

The power system consists of power generation, transmission, distribution, electricity and other equipment and its stove auxiliary system (relay protection, safety automatic, measurement, dispatching automation and communication devices), according to the specified technical and economic requirements, to convert primary energy into electrical energy and transmit and distribute it to users. The fundamental task of the power system is to provide sufficient, reliable, qualified and reasonable electrical energy to users.