Non-conventional Instrument Transformer Research Articles

Modelling and design of low-power, non-conventional current sensors based on smart materials for high-voltage transmission lines

This paper presents a new technique for measurement of current based on magnetic shape memory (MSM) smart alloys. MSM alloys undergo shape changes when exposed to magnetic fields. The non-conventional instrument transformer (NCIT) proposed in this paper utilises this property to measure current. There is a correlation between the magnetic field produced by a current and the shape change of an MSM material (MSM sensor). By exploiting this correlation, we have shown that it is possible to measure alternating currents (a.c.) in high voltage overhead transmission lines. A change in the length of the MSM element causes voltage output in a linear variable differential transducer. The design of the NCIT was optimised for transmission lines. Several designs of its magnetic circuit were simulated using finite element package ANSYS APDL. Several key parameters were investigated to evaluate their effects on the sensitivity of the NCIT. Results are presented as the relationship between the current in the conductor and strain (linear elongation) of the MSM element. A commonly used conductor in high-voltage transmission lines was modelled together with the MSM element and the magnetic circuit. Recommendations have been made on the design of NCITs considering various parameters. In addition, analyses of errors in ANSYS models for the magnetic circuit have been presented. The developed methodology and obtained results are verified by comparing them to the results obtained through an experiment done by a manufacturer of MSM materials.

Toward a Substation Automation System Based on IEC 61850

With the global trend to digitalize substation automation systems, International Electro technical Commission 61850, a communication protocol defined by the International Electrotechnical Commission, has been given much attention to ensure consistent communication and integration of substation high-voltage primary plant assets such as instrument transformers, circuit breakers and power transformers with various intelligent electronic devices into a hierarchical level. Along with this transition, equipment of primary plants in the switchyard, such as non-conventional instrument transformers, and a secondary system including merging units are expected to play critical roles due to their fast-transient response over a wide bandwidth. While a non-conventional instrument transformer has advantages when compared with the conventional one, extensive and detailed performance investigation and feasibility studies are still required for its full implementation at a large scale within utilities, industries, smart grids and digital substations. This paper is taking one step forward with respect to this aim by employing an optimized network engineering tool to evaluate the performance of an Ethernet-based network and to validate the overall process bus design requirement of a high-voltage non-conventional instrument transformer. Furthermore, the impact of communication delay on the substation automation system during peak traffic is investigated through a detailed simulation analysis.

Modelling and optimisation of design of non-conventional instrument transformers

In this paper, we have proposed, modelled and optimised several designs of non-conventional instrument transformer (NCIT) for high voltage overhead transmission lines (400kV). We have discussed several parameters and investigated how they influence the sensitivity of our NCIT, consisting of magnetic shape memory (MSM) element, magnetic circuit and an LVDT (linear variable differential transformer). One of the most used conductors in these lines, 528-Al1/69-ST1A ACSR conductor (old code MOOSE), was modelled together with the MSM element and the magnetic circuit in ANSYS APDL. Based on the obtained results we have given suggestions on how NCIT could be designed taking into account a choice of the most appropriate material for this application. The way how the model was developed was presented as well as calculations of errors in the model in ANSYS APDL for electromagnetic problems.

Modelling of non-conventional instrument transformers (NCIT) by Finite Element Method FEM

In this paper, we have shown that the proposed non-conventional instrument transformer using magnetic shape memory (MSM) alloys can be used for current measurement in high voltage overhead transmission lines. By modelling one of the most used conductors at high voltage overhead transmission lines (400kV, 300–600A, AC) and our sensor consisting of a magnetic circuit and an MSM element, NCIT’s design was optimised for these lines and it was shown that the typical values of electrical current expected in a normal working regime would trigger the MSM element. Different designs of magnetic circuits were modelled in ANSYS APDL and discussed, comparing the obtained results for several different materials for magnetic circuit.

A non-conventional instrument transformer

The paper describes a non-conventional instrument transformer (NCIT) offering the possibility of adapting the measuring points in the high-voltage power network to new states as a result of the impact of intermittent renewable energy resources, harmonic distortions evoked by switching apparatus and smart-grid systems, enabling prompt and accurate measurements in a wider frequency range at a higher dynamics, and providing more reliable operation of the power network. The features of the proposed NCIT are in using the low-power current transformers (LPCT) and in the measuring and processing electronics which are situated partially on the potential of high voltage (HV) line and partially on earth potential.

Research on Key Technology of Smart Substation with Intelligent Materials

Smart substation is the intelligent node of the smart grid, which plays a fundamental part in the construction of the smart grid. This paper presents the concept and the technical characteristics of the smart substation and some important aspects in the development of Substation Automation System (SAS): the meaning, technical characteristics and the development of IEC61850 which is the international and the best standard for the construction of SAS; different Substation Communication (SC) architecture to ensure the reliability, availability and survivability of the geographically distributed complex power; the characteristics of Non Conventional Instrument Transformer(NCIT), the Intelligent Switchgear as well as their implement.