A method for monitoring the line impedance of a protective earth (PE) conductor is provided. The method injects a small stimulus current at a frequency much higher than the grid frequency. The stimulus current circulates in the loops between a grid-connected device and a grid source, creating small voltage drops in the grid conductors, resulting in a common mode voltage which can be measured. The method then includes measuring the common mode voltage and the residual current at a point of common coupling (PCC). The method then includes monitoring the resistive and reactive parts of the line impedance. For example, the method can monitor the line impedance and report a broken PE conductor or a high PE resistance, beyond a given threshold where safety becomes a concern.

A method for monitoring the line impedance of a protective earth (PE) conductor is provided. The method injects a small stimulus current at a frequency much higher than the grid frequency. The stimulus current circulates in the loops between a grid-connected device and a grid source, creating small voltage drops in the grid conductors, resulting in a common mode voltage which can be measured. The method then includes measuring the common mode voltage and the residual current at a point of common coupling (PCC). The method then includes monitoring the resistive and reactive parts of the line impedance. For example, the method can monitor the line impedance and report a broken PE conductor or a high PE resistance, beyond a given threshold where safety becomes a concern.

Grounding simulation models for training linemen and other power or utility technicians are disclosed. The grounding simulation models can be configured to provide equipotential zone (EPZ) grounding training for high voltage electric power transmission. In some instances, the grounding simulation models can include a power pole assembly including power poles, a top conductor, a middle conductor, a bottom conductor and an optical ground wire (OPGW). In some instances, the grounding simulation models can include a lineman meter configured to emulate a utility worker operating on high voltage electric power lines. In some instances, the grounding simulation model can include step leads that can be positioned anywhere along a matrix pattern on a mounting board, wherein the step leads are configured to demonstrate step and touch potential. In some instances, the grounding simulation models can include a model wire puller and insulation and isolation platforms.

The application relates to a method and system for a pilot directional protection of LCC-HVDC lines based on virtual grounding resistance. The method comprises: Obtaining a conduction state information of a converter and characteristic parameters of a converter circuit within one commutation period after a fault occurs; according to the conduction state information and characteristic parameters, determining characteristic frequency of the circuit; according to the characteristic frequency and characteristic parameters, determining a virtual grounding resistance; according to the virtual grounding resistance, determining fault areas.

The application relates to a method and system for a pilot directional protection of LCC-HVDC lines based on virtual grounding resistance. The method comprises: Obtaining a conduction state information of a converter and characteristic parameters of a converter circuit within one commutation period after a fault occurs; according to the conduction state information and characteristic parameters, determining characteristic frequency of the circuit; according to the characteristic frequency and characteristic parameters, determining a virtual grounding resistance; according to the virtual grounding resistance, determining fault areas.