Design and implementation of fibre optical HV sensor in relay protection systems

Measurements in high voltage

High voltage measurements are very important as they are used in electrical power networks as a source of information to relay protection systems and load management systems. Electrical power is a very important source of energy. It plays an important role in the interdependence with other energy sectors like water, telecommunications, transport etc.

An electrical network can be defined as an interconnection of electrical components (e.g. switches, capacitors, inductors, and resistors) or an electrical model of the interconnection, which compromises of electrical components like current sources, voltage sources, inductances, resistances.

Electrical networks needs to be protected from faults, in-order to avoid power failures. The common way of protecting networks from faults is isolating the fault areas from the non-fault areas. Faults can be random and may be caused by common cause issues like lightning strikes, earthquakes, flooding.

The electrical protection schemes must be the starting points of measuring the voltages i.e. overvoltage (fault detection) in networks, there after instigating the clearing of these faults.

The protection systems usually consist of current transformers, voltage transformers, protective relays, circuit breakers. Conventional HV sensors have limitations like: inability to operate reliably and accurately in harsh environments, affected by EMI, low resolution etc.

The thesis addresses this by developing and implementing a reliable, robust Optical High Voltage Sensor and investigates other novel means of measuring voltages by using Bragg grating and optical Kerr.

Research Problems

Traditional High Voltage sensor for Relay Protection Systems (RPS) have known limitations. Problems such as electromagnetic interference, electrical insulation issues, inability to operate reliably in harsh environments etc.

The aim of the research is to design and implement an Optical High Voltage Sensor to be used in a Relay Protection System for Electrical Power Networks.

1. Prototype an optical voltage sensor to measure voltage up to 250V DC.
2. Simulate the sensor head of the sensor to determine its capability of measuring very high voltages. (up to 300kV AC)
3. Determine the Kerr effect on a fibre optics cable with has laser passing through it using RSoft software.
4. Model an Optical Kerr Cell using Maxwell software, in order to investigate its capability to measure voltages.
5. Verification and Validation of the High Voltage Optical Sensor
6. In-depth discussion of Relay Protection Systems in which the proposed High Voltage sensor can be used.