Rational reconstruction of sectioning posts of AC catenary at disconnectors

Operation of sectioning posts of the AC catenary at the disconnectors on the Gorkovskaya railway for a period of more than 60 years has shown its reliable operation, and the maintenance was reduced to a minimum. However, due to the growth of heavy haul and high-speed traffic on a number of sections, their reconstruction was required. In accordance with the current regulatory documents, such a reconstruction provides for the transfer of the operation of sectioning posts from disconnectors to circuit breakers. In connection with the reliable operation of the sectioning posts on disconnectors and the simplicity of their maintenance, it is proposed to expand the options for the reconstruction of the sectioning posts on the disconnectors and to introduce three reconstruction options into the regulatory documents. The first option provides for the reconstruction of the sectioning post with disconnectors by transferring it to the classic scheme with four switches, as indicated in the current regulatory documents. The second option provides for leaving the sectioning post at the disconnectors, but adding a fast-acting automatic reclosing device in the inter-substation zone in case of passing short circuits. The third option provides for the reconstruction of the sectioning post on disconnectors with the introduction of a vacuum circuit breaker into the bus of the post and a device for high-speed automatic reclosing and opening of the disconnector, in the zone of which a short circuit has occurred. The schemes of automatic devices for determining a stable (passing) short circuit in a traction network and a device for determining the location of damage are considered. The operation of the sectioning posts, reconstructed according to the indicated options, has been tested practically at the existing sections of the power supply of the traction network of the Gorkovskaya railway. All of them have shown high reliability.

Application of Estimation of Model Parameters for Protective Automation of Transmission Lines

Transmission lines are indispensable part of power transmission system, which are highly exposed to fault risk factors of environmental and anthropogenic nature. Therefore, protection and control have to be robust and reliable as possible. Distance protection and some of fault location methods, used today for transmission lines, operate within a limited scope of available information that can result in errors and incorrect operation, especially when faults have high transient resistance. In order to overcome these drawbacks of one-terminal-based distance protection and fault locations methods it is proposed to use a technique of estimation of unknown power system model parameters, solving these problems as an optimisation tasks. The scope of available information is extended by incorporation of all measurements, available from the controlled substation, thus eliminating necessity of long-distance communication networks, and by a separate stage of parameter estimation during the pre-fault regime, which is similar to estimation of fault parameters but operates with a nonlinear model reflecting the influence of governors. The Thesis provides modelling tools for both pre-fault and different fault regimes based on symmetrical component and topological modelling methods to accommodate the increased measurement scope. The proposed method was extensively tested considering two different strategies for selection of measured parameters used by the optimisation. The proposed method and its results is not limited to the fault location or distance protection, as the developed technique was also used to create a new method of an adaptive single-phase automatic reclosing algorithm. The proposed method can be used as a base for creation of robust algorithms and devices for the fault location, distance protection and single-phase automatic reclosing. It can also be modified or directly implemented for different transmission line automation and protection problems. The modelling tools described in the Thesis can be used for a further analysis and development of relay protection and automation.