Resonant overvoltage

Resonant overvoltage? HVHIPOT specializes in the production of series resonance, with a wide range of product selection and professional electrical testing. To find series resonance, choose HVHIPOT. 

In the power system, some inductive and capacitive components can form various oscillation circuits during system operation or failure. Under certain energy sHVHIPOTces, series resonance phenomena can occur, leading to severe overvoltage in certain components of the system. There are several types of resonant overvoltage:

(1) The linear resonant overvoltage resonant circuit is composed of inductive elements without iron cores (such as the inductance of transmission lines and leakage inductance of transformers) or inductive elements with iron cores that have excitation characteristics close to linearity (such as arc suppression coils) and capacitive elements in the system. 

(2) The ferromagnetic resonance overvoltage resonance circuit is composed of inductive components with iron cores (such as no-load transformers and voltage transformers) and capacitive components of the system. Due to the saturation phenomenon of iron core inductance components, the inductance parameters of the circuit are nonlinear. This type of circuit containing nonlinear inductance components will generate ferromagnetic resonance when certain resonance conditions are met. 

(3) Parameter resonance overvoltage is composed of a loop consisting of inductance components with periodic changes in inductance parameters (such as the synchronous reactance of a salient pole generator that varies periodically between Xd and Xq) and system capacitance components (such as no-load lines). When the parameters are matched, energy is continuously transmitted to the resonance system through the periodic changes in inductance, causing parameter resonance overvoltage. 

Characteristics of resonant overvoltage conditions

In a neutral ungrounded power system, due to the nonlinear excitation characteristics of electromagnetic voltage transformers (TVs), resonant overvoltage occurs when voltage fluctuations cause the reactance in the network to approach the capacitive reactance. Especially when encountering TVs and systems with poor excitation characteristics (prone to saturation) that experience single-phase to ground flashover or grounding, it is more likely to cause resonance overvoltage. Mild cases may cause the fuse of the TV to melt, short circuit between turns, or explode; Serious accidents such as lightning arrester explosions, bus short circuits, and power outages that pose a serious threat to the safe operation of power systems and electrical equipment can occur in severe cases.

The main measures to limit resonance overvoltage are:

(1) Improving the synchronicity of switch actions is important as many resonant overvoltages are caused under non full phase operating conditions. Therefore, improving the synchronicity of switch actions and preventing non full phase operation can effectively prevent the occurrence of resonant overvoltages. 

(2) Install a small reactance at the neutral point of the parallel high-voltage reactor

This measure can block the transmission of power frequency voltage and series resonance during non full phase operation. 

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