Optical voltage sensor for MV networks

Photonic Voltage Transducer with Lightning Impulse Protection for Distributed Monitoring of MV Networks

“…The photonic voltage transducer is to be connected between one line of an 11 kV system and earth, and hence, its rated voltage is 6.35 kV (9 kV peak) [10]. For a primary rated voltage of 6.35 kV, the relevant rated voltage factors are 1.2 and 1.5, which are applicable to measurements between phase and earth on a continuous and 30 s duration basis, respectively [10]. Additionally, the device must withstand the rated power frequency for 60 s and 30 positive and negative impulses of the rated lightning impulse voltage levels as summarized in Table 1.…”

“…In the originally proposed design [10], shown in Figure 1, an FBG sensor was suspended between two quartz arms bridging a cylindrical block of PIC181 piezoelectric material, having a diameter of 40 mm and a thickness of 40 mm (2 × 20 mm thick cylinders). The FBG was attached to the arms with a UV epoxy and the attachment method was aimed at providing strain amplification.…”

“…To enable DC measurement, the sensor was equipped with an additional temperature-sensing FBG to enable temperature compensation in this mode of operation. The sensor was placed in a hollow core composite insulator and potted in a dielectric gel, offering a dielectric strength of 23 kV/mm, to provide additional protection against electrical discharge and external vibrations [10]. In order to allow for the installation on an 11 kV overhead line, a PVT prototype was tested against 75 kV lightning impulses of both polarities according to the IEC 60044-7 standard.…”

“…To enable access to multiple, remote, distributed, passive current and voltage measurements over long distances that can be applicable to a wide range of metering and protection applications, the concept of a photonic sensors suite utilizing fibre Bragg grating (FBG) sensors and piezoelectric transducers was proposed by the authors [ 8 , 9 , 10 , 11 ]. This included variants of the core technology—from using low-voltage piezoelectric stacks to measure the output of a conventional CT or Rogowski coil for current measurement [ 8 , 9 , 12 ], through to using the same approach for sensing the secondary voltage of a capacitor divider to achieve voltage measurement at 132 kV [ 11 ]—to direct the voltage measurement at medium voltage by using larger piezoelectric transducers that are capable of being exposed to multi-kV-level voltages [ 10 ]. The latter device has the benefit of using a “hard” piezoelectric transducer that generally has a better stability and long-term performance as opposed to the “soft” piezoelectric transducers [ 13 , 14 ].…”

Optical Voltage Transducer for Embedded Medium Voltage Equipment: Design and Parameters Optimization

“…Alternatively, an optical scheme consisting of an electrooptic crystal, polarizing bulk elements and three optical fibres [3] had been proposed for the development of an OVS Sensor. More recently an optomechanical solution been presented, in which the Voltage sensing transducer is a piezoelectric element and a fibre Bragg grating (FBG) basically acts as an optical strain sensing element [4]. With respect to these previous solutions, the optical Voltage sensor described by the same authors in [5], is based on a simple optical layout and potentially low cost, due to the use of standard telecom optical components.…”