| The extra high voltage (EHV) and ultra high voltage (UHV) power transmission systems play significant roles in power systems of our country. In EHV and UHV power lines, long distance transmissions require large charging power, and the line voltage is very high while on light load. To solve the problem, the HV shunt reactor must be installed. The faults in HV shunt reactor will seriously affect the safe operation of the whole power system. The phase separation structure is generally applied in extra and ultra HV shunt reactors, and thus the inter-phase short circuit is not easy to happen. However, the main faults in such shunt reactors are the inter-turn short circuit. The current in the reactor is through type, the differential protection is unable to effectively protect the inter-turn short circuit faults, and thus it is meaningful to study the protection of the HV shunt reactors.This dissertation firstly analyzes the characteristics of the zero sequence power direction protection, the negative sequence power direction protection and the comparison of absolute value with zero sequence direction protection by using MATLAB/Simulink. In simulations, a 500 kV transmission line with distributed parameters is employed. The performance of the protections under the faults such as inter-turn short circuit, grounded short circuit in the region, grounded short circuit outside the region, open-phase operation are analyzed. It can be seen that if we reduce the block current, false tripping may be occurred during the period of open-phase operation and then automatic reclosing lock. If we increase block current, the protection failure regions will be large. In addition, improved suggestions are proposed for the negative sequence power direction protection and the comparison of absolute value with zero sequence direction protection schemes.The measured negative sequence impedances under the inter-turn short circuit and grounded short circuit in the region are very different from that under other running status. According to this feature, a negative sequence impedance based inter-turn protection is proposed. By using Simulink, the performance of this protection is simulated. Simulation results show that the initialization of the proposed inter-turn protection is very easy to determine. To solve the false tripping problems during the period of open-phase operation and then automatic reclosing lock, the moving average process is added, which makes the protection using very small block current and has very high tripping sensitivity. Also, the false tripping can be avoided. By using digital signal processor (DSP), the negative sequence impedance based inter-turn protection is implemented, and the hardware-in-the-loop tests are made on the RT-LAB simulation test bed. Experiment results verify the effectiveness of the negative sequence impedance based inter-turn protection.This dissertation investigates the inter-turn protection employing the Reduced Multivariate Polynomial (RMP). The RMP can be taken as a novel neural network, the zero sequence voltage and the zero sequence current are the two inputs, one output determines whether the inter-turn protection is tripping or not. The algorithm to obtain the weight by using the training sequence is proposed, and the weight can be determined by using the algorithm once, which does not need repeated iterations. Simulation results show that the RMP can well implement the inter-turn protection and ensure the safe operation of the HV shunt reactors.Compared to the commonly used simplified analysis method, the simulation method e mployed in this dissertation is more accurate and more comprehensive. Also, the simulatio n method can also find the problem that the simplified analysis method is hard to find. This dissertation proposes two inter-turn protection schemes, which plays a positive role in imp roving the protection performance of the HV shunt reactor, and is beneficial to the safe ope ration of the ultra and ultra HV power transmission systems.
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