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Accurate parameter estimation of power system equipment's are very important for getting precise models which can be further used for protection settings and stability studies. This paper presents parameter estimation method for transformers using terminal measurements available from IEDs used for transformer protection. Identifying the equivalent circuit and estimating the transformer parameters including turns ratio, leakage reactance, shunt reactance and loss components are explained in this paper. The paper introduces practical scenarios where the measurement data is highly erroneous. These bad measurements need to be detected and corrected to improve the estimation accuracy. This paper put forward an accurate parameter estimation method that consider the presence of measurement errors. Identifying the bad measurement and correcting this bad data is also considered in this work. The estimation accuracy of the proposed methods is verified by simulation in PSCAD/EMTDC and testing in MATLAB.

Cascade tripping of power lines triggered by maloperation of zone-3 relays during stressed system conditions, such as load encroachment, power swing and voltage instability, has led to many catastrophic power failures worldwide, including India blackouts in 2012. With the introduction of wide-area measurement system (WAMS) into the grids, real-time monitoring on transmission network condition is possible. A phasor measurement unit (PMU) sends time synchronized data to phasor data concentrator which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for slower form of protection. In this work, a method to identify the faulted line using synchronized data from strategic PMU locations is proposed. Subsequently, a supervisory signal is generated for specific relays in the system for any disturbance or stressed condition. For a given system, an approach to decide the strategic locations for PMU placement is developed, which can be used for determining the minimum number of PMUs required for application of the method. The accuracy of the scheme is tested for faults during normal and stressed conditions in New England 39 bus system simulated using EMTDC/PSCAD software. With such a strategy, maloperation of relays can be averted in many situations and thereby blackouts/large-scale disturbances can be prevented.

Cascade tripping of power lines triggered by maloperation of zone-3 relays during stressed system conditions, such as load encroachment, power swing and voltage instability, has led to many catastrophic power failures worldwide, including India blackouts in 2012. With the introduction of wide-area measurement system (WAMS) into the grids, real-time monitoring on transmission network condition is possible. A phasor measurement unit (PMU) sends time synchronized data to phasor data concentrator which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for slower form of protection. In this work, a method to identify the faulted line using synchronized data from strategic PMU locations is proposed. Subsequently, a supervisory signal is generated for specific relays in the system for any disturbance or stressed condition. For a given system, an approach to decide the strategic locations for PMU placement is developed, which can be used for determining the minimum number of PMUs required for application of the method. The accuracy of the scheme is tested for faults during normal and stressed conditions in New England 39 bus system simulated using EMTDC/PSCAD software. With such a strategy, maloperation of relays can be averted in many situations and thereby blackouts/large-scale disturbances can be prevented.

This paper investigates on distance relay characteristic for hybrid line; an overhead transmission line combined with a cable. Introducing ABCD parameter approach to sequence network the apparent impedance equation is derived that includes line capacitance. For a 400 kV hybrid transmission system results show that shunt capacitance has significant effect on settings for adaptive relaying. It is observed that the trip characteristic for hybrid line is unique. An adaptive setting method using local information is proposed and tested using simulated data obtained through EMTDC-PSCAD.

This paper presents adaptive zone-2 distance relay characteristics for multi-terminal power transmission system using PMU data. The apparent impedance equation which includes the infeed, outfeed and line shunt capacitance of the multi-terminal system is derived. For a 400 kV multi-terminal system, the results indicate that the trip boundary is significantly changing with the operating conditions. An adaptive setting method using Phasor Measurement Unit (PMUs) data is proposed and tested using simulated data obtained through EMTDC-PSCAD.