Power system software used for analysis and dynamic simulation and relay settings require accurate model parameters of different elements for precise results. For this, transmission line parameter verification is necessary at times, which changes due to atmospheric condition and aging. This paper presents a method for estimating the parameters of series compensated line online using synchronized time-domain data captured by the intelligent electronic devices at both ends of the line, which is free of the compensation model. The method uses traveling waves generated during disturbance to obtain the propagation constant of the line, which is used to estimate the resistance and the characteristic impedance of the line. Subsequently, the inductance and capacitance of the line are calculated. The proposed method is tested using PSCAD/EMTDC simulation data of an actual series compensated line in Indian power grid. Results demonstrate the accuracy of the proposed method.

This paper presents a fault location method for multi-circuit series compensated line using phasor data from intelligent electronic devices available at both ends. In case of unavailability of synchronized data, analytical synchronization is obtained using an operator. In the formulation, the method considers untransposed line sections resulting on two sides of the fault and the distributed nature of line. For a healthy phase, currents on two sides at the fault point are equal unlike different currents on two sides in a faulted phase. This is checked over the line length and the fault location is pinpointed. The method does not require the model of the series compensation placed at any location on the line and can be used for both inter- and intra-circuit faults. It also considers reactive component of the fault impedance for accurate fault location. The method is tested using PSCAD/EMTDC simulations for a multi-circuit series-compensated line in Indian power grid. Evaluation study confirms the validity of the method for various faults.

In a transmission network, autoreclosing provides quick restoration of the line for transient faults and improves system stability. Autoreclosing during permanent fault may damage power system elements. This paper presents a method to block autoreclosing for permanent line-to-ground faults on multicircuit series compensated transmission line using synchronized measurements from both ends. The method utilizes measurements from the healthy phases of the line to calculate an index, which determines the persistence of a fault to control the reclosing. In the case of a transient line-to-ground fault, the index is high during the fault and zero after extinction of the secondary arc. The index can be used to modify the dead time of the recloser and thereby reclosing during fault (both transient and permanent) is prevented. The proposed method is tested using the sample data obtained from EMTDC/PSCAD simulation of an actual series compensated line in the Indian power grid. Results demonstrate the accuracy of the proposed method.

Regulating agencies mandate that model verification of power system components must be performed to make sure that system analysis software performs accurately. Such verification is necessary for series compensation devices used in transmission systems, since they deteriorate due to aging or prolonged subjection to stressed conditions, leading to changes in compensation levels or voltage-current characteristics of the metal-oxide varistor (MOV) protecting them. This paper presents a method that uses synchronized time-domain data captured by intelligent electronic devices at both ends of a line for model verification of a fixed series compensation device installed at one location in the line. The electromagnetic transient line model is used to calculate the current and voltage across the compensation device, which, in turn, are used to determine the actual compensation and the actual voltage-current characteristics of MOVs. These characteristics are used to detect failures in MOV and spark gap. PSCAD/EMTDC is used to test the method.

To plan operations and avoid any grid disturbances, power utilities require accurate power generation estimates for renewable generation. The generation estimates for wind power stations require an accurate prediction of wind speed and direction. This paper proposes a new prediction model for nowcasting the wind speed and direction, which can be used to predict the output of a wind power plant. The proposed model uses perturbed observations to train the ensemble networks. The trained model is then used to predict the wind speed and direction. The paper performs a comparative assessment of three artificial neural network models. It also studies the performance of introducing perturbed observations to the model using six different interpolation techniques. For each technique, the computational efficiency is measured and assessed. Furthermore, the paper presents an exhaustive investigation of the performance of neural network types and several techniques in training, data splitting, and interpolation. To check the efficacy of the proposed model, the power output from a real wind farm is predicted and compared with the actual recorded measurements. The results of the comprehensive analysis show that the proposed model outperforms contending models in terms of accuracy and execution time. Therefore, this model can be used by operators to reliably generate a dispatch plan.

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 Indian blackouts in 2012. With the introduction of wide-area measurement systems (WAMS) into the grids, real-time monitoring of transmission network condition is possible. A phasor measurement unit (PMU) sends time-synchronized data to a phasor data concentrator, which can provide a control signal to substation devices. The latency associated with the communication system makes WAMS suitable for a 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 a 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 article is part of the themed issue ‘Energy management: flexibility, risk and optimization’.