An advanced electricity infrastructure for efficient and reliable delivery of offshore renewable energy to onshore grids calls for High Voltage direct current (HVdc) transmission networks. With the advancement of power electronics, HVdc networks have evolved from point-to-point two terminals to Multi-Terminal direct current (MTdc) networks. For efficient operation of MTdc networks, fast and accurate methods of fault detection and isolation is a necessity. Traditional ac breakers fail to protect the system from dc faults due to their slow operational speed. The dc faults if not detected and removed can cause catastrophic damages to the network. This dissertation analyses the several stages of a dc fault and their impacts. Several specially designed dc breaker studies have been performed and evaluated. Hybrid dc circuit breaker (dcCB) has been found to be a viable choice for dc fault interruption owing to its fast operation and lower conduction losses. The major contributions of this dissertation are: (1) Spectral analysis of traveling waves using wavelet transform to detect faults; (2) Development of an efficient and robust non-communication-based algorithm for detection of fault; and finally (3) A non-intrusive method of fault location by analyzing the natural decay of line current after proper fault detection andisolation. Due to the absence of reactance in dc transmission lines and cables the rate of rise of fault current is high. Thus, the window of fault detection is very short for dc systems. Fault detection in dc systems is challenging due to the presence of common terminals and is affected by sensitivity and reliability issue with existing algorithms. This dissertation analyses the effects of faults on HVdc transmission systems and proposes two methods based on traveling wave detection through application of wavelet transform and also by the direction of arrival of current and voltage transients for efficient fault detection. Traveling wave are generated at the onset of faults. These fault transients are highly informative and help to provide us with the idea of time and location of the faults. With the application of wavelet transform, these transient signals are analyzed to detect and isolate the faults using hybrid dc breakers.Present communication technologies do not work faster than the speed of fault propagation. Most of the suggested fault detection methods require communication for efficient operation. Post-fault voltage and current are comprised of a transient portion from the generated traveling waves on the pre-fault voltage and current. By isolating the current and voltage transients and analyzing their direction of arrival at the hybrid dcCB’s, a faulted section of the network can be determined. All the connected dc breakers are operated individually, and the proposed methodology helps to prevent any misoperation of the breakers even on ac side faults. Finally, MTdc networks are installed in remote locations. Proper location of fault is a challenge. The natural dissipation of the circuit parameters is considered for fault location. A relationship between the natural frequency of oscillation of the fault current and fault location has been established. The hybrid dcCB interrupts the fault current and the line current attenuates under the absence of any driving voltage source. The line capacitance discharges into the fault at a damping frequency and a rate of attenuation. Utilizing these information’s, the fault location in a MTdc network is achieved. With the current advancements in MTdc network installations for off-shore renewableenergy integration, the proposed fault detection and location techniques can be utilized to develop resilient and robust networks. All the proposed methods were justified theoretically and their performances were evaluated through simulation studies.