By hvhipot 
HV Hipot Electric Co., Ltd. specializes in producing series resonance (also known as series resonance test device). Next, we will share with you the knowledge of ultra-high voltage shunt reactors that you may not know.
Ultra high voltage parallel reactor is one of the devices in the series resonance device. The series resonance mainly consists of: the series resonance test device includes: frequency conversion series resonance, excitation transformer, reactor, voltage divider, capacitor, and control box. Huatian Power Company is a manufacturer of series resonance test equipment, specializing in the production of reactors. The variable frequency series resonance test device is suitable for AC withstand voltage testing of 10KV, 35KV, 110KV, 220KV, and 500KV polyethylene power cables. The series resonance test device is suitable for AC withstand voltage testing of 60KV, 220KV, and 500KV GIS. The series resonance test device is suitable for power frequency withstand voltage testing of large transformers and generator sets, induction withstand voltage testing of power transformers, and measurement of grounding resistance. This article mainly introduces the protection and various functions of ultra-high voltage parallel reactors during operation.
Function of ultra-high voltage parallel reactor
Ultra high voltage shunt reactors have multiple functions to improve the reactive power related operating conditions of power systems, mainly including:
1. The capacitance effect on lightly unloaded or lightly loaded lines to reduce transient overvoltage at power frequency;
2. Improve voltage distribution on long-distance transmission lines;
3. To balance the reactive power in the line as much as possible under light load, prevent unreasonable flow of reactive power, and also reduce power loss on the line;
4. Reduce the steady-state power frequency voltage on the high-voltage bus when the large unit is parallel to the system, in order to facilitate synchronous parallel operation of the generator;
5. Prevent self excitation resonance phenomenon that may occur in generators with long lines;
6. When using a small reactance grounding device for the neutral point of a reactor, a small reactor can also be used to compensate for the phase to phase and phase to ground capacitance of the circuit, in order to accelerate the automatic extinguishing of the secondary current and facilitate its use.
The wiring of reactors can be divided into two types: series connection and parallel connection. Series reactors usually serve to limit current, while parallel reactors are often used for reactive power compensation.
1. Half core dry-type shunt reactor: In ultra-high voltage long-distance transmission systems, it is connected to the tertiary coil of a transformer. Used to compensate for the capacitive charging current of the circuit, limit the system voltage rise and operating overvoltage, and ensure the reliable operation of the circuit.
2. Half core dry-type series reactor: installed in the capacitor circuit, starting when the capacitor circuit is put into operation.
Protection of ultra-high voltage parallel reactor
Due to limitations in external dimensions, weight, and transportation equipment, an increasing number of ultra-high voltage parallel reactors are adopting phase separated structures. Therefore, the common faults of ultra-high voltage parallel reactors are single-phase grounding faults and inter turn pipeline faults. At the same time, in order to ensure the linear inductance characteristics of the parallel reactor, the iron core is usually made with an air gap, and the wire cakes on the iron core produce significant vibration and noise under the action of alternating electromagnetic force. Meanwhile, due to various factors affecting the transportation, installation, and use of reactors, they are prone to various types of faults during operation. In contrast, the correct operation rate of ultra-high voltage parallel reactor protection is very low compared to that of other main equipment protection.
For the protection of ultra-high voltage parallel reactors, in addition to non electrical protection such as gas, pressure release, and winding temperature rise, differential protection (including zero sequence differential) is commonly used for internal grounding faults of windings in reactor protection configurations using electrical quantities, and has high sensitivity.