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Current differential protection is based on Kirchhoff s current law. Protection relays in different parts of the network analyse the vector sum of the measured currents and detect faults in the protected area as show in Figure 1. Differential definition:
With the integration of various distributed generators (DGs), traditional distribution networks have been transforming into active distribution networks (ADN). One typical challenge of the integration of DGs is that the fault current can possibly exceed the opening capacity of the related breakers. This paper presents a novel distributed solution, which can be hosted in the distributed feeder relays...
The DC-side line faults in high-voltage direct-current (HVDC) systems utilising voltage-source converters (VSCs) are a major concern for multi-terminal HVDC systems in which complete isolation of the faulted system is not a viable option. A number of challenges are posed by both pole-to-pole and pole-to-ground faults including the presence of very fast and high amplitude discharge current from the...
This work presents the outcome of a comprehensive study that assesses the transient behaviour of two high voltage direct current (HVDC) networks with similar structures but using different converter topologies, termed two-level and half-bridge (HB) modular multilevel converter (MMC). To quantify the impact of converter topology on DC current characteristics a detailed comparative study is undertaken...
A Multi-Terminal High Voltage Direct Current (MT-HVDC) network is being considered for utilising the full potential of offshore wind power whereas its realisation is currently being hampered by protection issues. In this paper, a protection strategy for future DC grids based on Modular Multilevel Converter (MMC) based HVDC system is presented. Firstly, a fault detection technique based on initial...
A new technique to detect the fault direction of single-phase-to-earth fault for Petersen's Coil compensated earthed power system is presented in this paper. The proposed technique can make a precise decision on detecting the single-phase-to-earth fault, not requiring higher frequency sampling rates, higher accuracy measurements. It can be implemented in traditional feeder relay with low sampling...
A new technique to detect the fault direction of single-phase-to-earth fault for Petersen's Coil compensated earthed power system is presented in this paper. The proposed technique can make a precise decision on detecting the single-phase-to-earth fault, not requiring higher frequency sampling rates, higher accuracy measurements. It can be implemented in traditional feeder relay with low sampling...
Traditional current differential protection is based on Kirchhoffs Law, certainly is severely influenced by the distributed capacitance current. A new traveling wave based differential protective principle is proposed by employing the characteristics of current traveling waves for the distributed parameter line model. There are fixed propagation relations between traveling waves of terminals as the...
A novel electro-magnetic transient analysis technique by means of the orthogonal projection method for lossy transmission line is proposed. By employing the proposed method, the traveling waves propagating from one terminal to another can be quickly obtained with less amount of computation under any larger sampling steps. First of all, the differential function to variable time can be approximated...
In this paper, the traveling wave based differential protection for HVDC transmission line is proposed, in which the backward traveling waves in mode 1 are employed to establish the traveling wave based protection, at the same time the zero-mode current detector is utilized to determine that which is the faulty line for bipolar HVDC lines. The operating traveling wave is the differential of the backward...
A novel electro-magnetic transient analysis technique based on approximation and z-transform theorems is proposed in this paper. The differential function relates to time is firstly approximated to convolution of the projection of differential operator and the function itself, subsequently the digital equation of transmission line is established. The z-transform is employed to obtain the solution...
The conventional approaches to electro-magnetic transient analysis is based on the Laplace transform. This method has certain drawbacks in terms of complexity. A new technique based on the projection operator reduces computational complexity and offers the possibility of real time application. After projection onto orthogonal bases, which map to a function space related to time variable t over a given...
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