Abstract
Electric power system reactive compensation is a very important fault, and its problems should not be taken lightly. In this paper, the general types of reactive compensation in electric power systems and their advantages and disadvantages are introduced. Moreover, the causes and solutions of the problems caused by various types of reactive compensation are discussed.
Keywords: Electric power system; Reactive compensation; Fault problems
1 Introduction
Electric power system reactive compensation is an important part of the power system, which is mainly used for system voltage stability, reliability and quality of the power supply. Due to the large impact and the huge cost of equipment transformation, the application of reactive compensation measures is more and more popular and imperative.
At present, the various types of reactive compensation equipment and technology used in electric power system have different advantages and disadvantages. According to the requirements of the power system, suitable type of reactive compensation strategies and measures should be selected based on the actual conditions of the power system.
2 Types of Reactive Compensation
Reactive power compensation in electric power system mainly includes static reactive power compensation, surge arrester compensation, self-excitation compensation and substation ground reactive grid compensation.
2.1 Static reactive power compensation
Static reactive compensation mainly includes capacitors, reactors, automatic reactive power compensation equipment, flexible AC transmission system (FACTS) and HVDC three-winding transmission equipment.
Static capacitors and reactors are suitable for locations where the load is light and the requirements for reactive power compensation are low. It has the advantages of relatively low investment, convenient adjustment and simple management, but it has the problems of low accuracy and weak dynamic response.
Automatic reactive power compensation equipment can be divided into two categories: on-load and offline. The on-load compensation equipment is mainly used for occasions where the requirement of reactive power compensation is relatively high and the load is relatively stable. It has the advantages of fast response speed, high dynamic response speed and low switching operation. The offline type requires manual switching, so it has poor dynamic response and poor compensation performance.
FACTS is mainly used for long-distance transmission or middle loop compensation or reactive power adjustment which has the requirement of high accuracy and fast response. It has the advantage of precise adjustment and strong dynamic response.
HVDC three-winding transmission is mainly suitable for large scale long-distance transmission or weak grid compensation. It has the advantages of low loss and high efficiency, but it is suitable for limited areas due to its high cost.
2.2 Surge arrester compensation
Surge arrester compensation is mainly used for scene large load changes and other occasions where the requirement for reactive power compensation is low. It has the advantages of low cost and simple control, but it cannot bear the momentary over-voltage.
2.3 Self-excitation compensation
Self-excitation compensation is suitable for special occasions such as isolated insulators where reactive power compensation is needed. It has the advantages of no extra external power supply, wide area and convenient control, but the long time device is easily damaged and the frequency pulse is easy to cause harmonic wave.
2.4 Substation ground reactive grid compensation
The substation reactive grid compensation is suitable for the scene of high accuracy and fast response requirement for reactive compensation, but it is not suitable for the scene of large load change because it has low dynamic response speed.
3 Problems of Reactive Compensation
In practical application, the various types of reactive compensation have different problems.
3.1 Problems in static reactive power compensation
The capacitors and reactors used in static reactive power compensation are easily damaged by lightning strikes and fault current, resulting in burning, smoke, and even fire.
The static reactive power compensation devices may be mis-operated, leading to over-compensation of reactive power, resulting in further unstable voltage or overvoltage.
In addition, improper maintenance or operation of static reactive power compensation devices can also lead to equipment faults.
3.2 Problems in surge arrester compensation
The surge arrester will be destroyed by the lightning current, resulting in the failure of the arrester and the burning of the arrester.
3.3 Problems in self-excitation compensation
The self-excitation compensation device can cause the current and voltage to over-excitation when the load changes suddenly, and even cause the device to be damaged.
In addition, the self-excitation compensation device is prone to harmonic resonance, which leads to vocal distortion.
3.4 Problems in substation ground reactive grid compensation
The substation ground reactive grid compensation device may cause distorted waveforms, resulting in an increase in power loss.
4 Causes and Solutions
Reactive compensation has certain problems, and these problems are caused by different causes.
4.1 The causes of static reactive power compensation problems
The cause of the static reactive power compensation devices’ fault may be the incorrect selection of compensation equipment, the improper maintenance of equipment, or the incorrect setting of parameters.
4.2 The causes of surge arrester compensation problems
The problems of surge arrester compensation may be caused by incorrect selection of arresters, incorrect installation or adjustment, undervoltage or overvoltage and other factors.
4.3 The causes of self-excitation compensation problems
The problems of self-excitation compensation may be caused by the incorrect choice of parameters, the selection of inappropriate device, or the incorrect setting.
4.4 The causes of substation ground reactive grid compensation problems
The causes of the substation ground reactive grid compensation problems may be the incorrect selection of devices and incorrect parameter settings.
Since the causes of different compensation problems are different, the corresponding measures should also be different.
4.1 Solutions for static reactive power compensation problems
Check whether the parameters set on the equipment are reasonable, clean the equipment regularly, and reduce the number of start-stop operations.
4.2 Solutions for surge arrester compensation problems
The lightning arrester should be selected correctly, and the installation should be done in accordance with the regulations, ensuring that the lightning arrester is grounded reliably.
4.3 Solutions for self-excitation compensation problems
The selection of self-excitation compensation parameters should be accurate, and the choice of the proper device should be based on the actual conditions of the power system.
4.4 Solutions for substation ground reactive grid compensation problems
The selection of ground grid compensation devices should be based on the actual situation of the power system and the characteristics of the fault.
5 Conclusion
Reactive power compensation is very important for the power system. The various types of reactive power compensation have their own advantages and disadvantages. In the process of application, due to the improper operation and selection of equipment, the various problems are more or less generated, resulting in various losses. Therefore, the selection and maintenance of reactive power compensation equipment should be done more carefully to ensure the safe and orderly operation of the power system.
