PSCAD Program Research Articles

Study of Problem and Effect Mitigation Technique of Unbalance Capacitance in 500 kV Single Phase Transformers

This article presents the study of the effect of unbalanced stray capacitance in single-phase 500 kV power transformers and establishes the mitigation technique. The power transformers were operated in Wang Noi Substation for transmitting the electrical power. There are 3 units of single-phase power transformer. Previously, a transformer of phase B failed after being serviced for several years. Thus, the new power transformer was ordered instead of the failed one. However, once the new system had been operated, the hotspots at the surge arrester of tertiary winding (22 kV) were found and the unbalance of phase voltages was observed, resulting in overvoltage as a root cause of the problem. Once a thorough investigation was done, it was found that there was an effect of unbalanced stray capacitance between tertiary winding and ground core since the new power transformer has some different designs compared with the remaining. Hence, the mitigation technique was performed by adding the capacitor parallel to the tertiary winding until the voltage balance was achieved. Simulation with the PSCAD program was performed to determine the optimum value for additional capacitors, i.e., voltage balance, using an iterative method. In this article, the capacitors used for additional were capacitor voltage transformers, which have been installed. As a result of the troubleshooting, the voltage at the 22 kV bus was more balanced as well as not causing overvoltage, and the hotspots at the surge arrester of tertiary winding were not detected resulting in gaining the stability and reliability of using these transformers.

Tracing passive traveling surge-based fault management control scheme in unearthed distribution systems

In this paper, a novel enhanced centralized fault management technique is proposed for smart unearthed distribution systems based on tracing passive traveling waves. The main objective of the proposed scheme is to efficiently identify the faulted section among multiple short-length sections within the distribution system. This is accomplished by installing synchronized surge detectors at both the lateral panel substations and the ends of branches. The identification process relies on analyzing the amplitudes and time stamps of the first arrival waves of the voltages. The distribution system is divided into zones based on the number of lateral panel substations, and the proposed approach encompasses three essential steps: determining the faulted zone, identifying the faulted path within the determined zone, and precisely pinpointing the faulted section. The faulted zone is determined by comparing the energies of the first arrival waves across all lateral panel substations. To identify the faulted path and section, two criteria and a voting system are proposed. The strength of the proposed scheme lies in its ability to cover all possible fault scenarios at various locations. Extensive tests are conducted using the detailed simulation of the IEEE 33-bus system with the PSCAD program. The mathematical core of the proposed approach is implemented using MATLAB. The results obtained from these simulations confirm the high reliability of the proposed fault management scheme, making it a viable solution for implementation in distribution systems.

Examination of EV Abilities to Provide Vehicle-to-Home Service in Low Voltage Installation

This paper deals with the application of an electric vehicle (EV) motor inverter and its batteries as an energy storage device supporting the operation of home electrical installation. This additional functionality of EV is called a Vehicle-to-Home (V2H) service. Two kind of services are considered: a peak shaving and an emergency power supply. The simulation model developed in the PSCAD program is presented. It allows for the examination of the EV battery control and operation during EV driving and parking. Additionally, it allows an evaluation of the availability of home installation for the V2H service. Control algorithms enabling the implementation of discussed work options are presented. Results of simulations are presented illustrating the EV control and operation in different operational modes.

Output power smoothing of wind power plants using self-tuned controlled SMES units

This paper exhibits a new application of the continuous mixed p-norm (CMPN) algorithm to self-tune all controlled superconducting magnetic energy storage (SMES) units to smooth wind power plants output power. The proposed algorithm is applied to self-tune all PI controllers of these storage units. In the present article, two wind farms are connected with the power grid. Each wind farm is equipped with a self-tuned (ST) controlled SMES unit. The control strategy of this unit is based on a voltage source converter (VSC) and a DC chopper. The VSC is implemented to control the reactive power and the DC chopper is utilized to control the real power exchange with the power grid. These aforementioned power electronic circuits are fully controlled by the proposed CMPN-ST-PI controllers. To achieve more realistic studies, measured values of wind speed that captured from Hokkaido wind power plants are implemented in system investigation. In addition, the turbine model depends on a two-mass structure, which highly affects system dynamics. Moreover, a practical SMES device of a rated capacity of 10 MVA, which is established in Kameyama, is joined the PCC of wind power plants. The proposed self-tuned controller is validated by using the simulation results, which are extensively performed on PSCAD program. The effectiveness of proposed adaptive controlled SMES devices is compared with that obtained by using optimal genetic algorithm-based PI controlled SMES devices under wind speed uncertainty conditions. With these CMPN-ST-PI controllers, the output power of wind power plants can be further smoothed and its fluctuations can be depressed.

Prevention of voltage instability in radial distribution system during fault occurrence

One of the most important fundamentals required for the rapid progress of technology, is stability in power systems. Therefore, with the power systems used for transfering energy over long distances, alongside the exposure of natural phenomena and errors, the stability of voltage protection becomes a necessity for economic and occupational safety reasons. In this paper, the analysis of the level of the voltage of the distribution network was studied by linking the capacitor bank after the network was exposed to error. A study was carried out for the compacted dynamic after connecting the capacitor bank. A PSCAD program was used to simulate a complete electrical distribution system and test results were taken from the same program.

Online condition monitoring of surge arresters based on third-harmonic analysis of leakage current

Surge arresters play an important role in maintaining the reliability and protection of the high voltage power systems. Various diagnostic online monitoring methods of surge arrester are based on the decomposition of the measured leakage current into their capacitive and resistive components. The arrester's resistive component of the leakage current, in particular, the third harmonic component, is known as to be directly related to the degree of degradation of the ZnO blocks. This paper proposes an online monitoring technique for the surge arrester under dry and pollution conditions when measuring either the total leakage current or both the internal and external leakage currents of three different types of surge arresters. This technique based on feature extraction of the magnitudes, frequencies, and phase angles of all frequency components of the real measured current signals using Prony analysis-Hilbert transform approach and MATLAB program. The observed results illustrate the viability of this technique for online monitoring of surge arrester. Furthermore, the effect of voltage harmonics on the measured leakage currents is investigated through surge arrester model simulation performed with PSCAD program.

Influence of Modeling Methods on the Calculated Lightning Surge Overvoltages at a UHVDC Converter Station Due to Backflashover

The insulation coordination of the converter station is very important for the security and economy of the UHVDC power transmission system, and lightning surge overvoltages at the converter station should be calculated accurately. This paper mainly analyzes the influence of modeling methods on the lightning surge overvoltages caused by the backflashover of the incoming dc transmission lines by using the PSCAD program, such as the selection of lightning stroke current waveform, tower model, flashover criterion of the insulator, and so on. The simulation results show that modeling methods have a great influence on the backflashover lightning withstand level of the incoming dc transmission lines, but their influences on the lightning surge overvoltages of the equipment in the converter station are not so obvious.

PV 어레이의 계통연계 모의를 위한 PSCAD 사용자 정의 모델 개발

Since large and small scale photovoltaic(PV) systems have been commercialized in many countries, it is necessary to assess the effects of PV systems on the electric power system. For this, the development of accurate simulation model of PV arrays is very important. PSCAD/EMTDC, a widely used simulation tool for analyzing the transient behavior of electrical apparatus and networks, does not have a standard model of a PV array. Therefore in order to simulate the PV array, users have to develop their own simulation model. However, the block-diagram-based model is very complicated, and it is hard to modify the model parameters. In this study, we develop the user-defined model of a PV array by using the Design Editor, which is provided by PSCAD program. The mathematical model of a PV array and the method to determine the parameters of nonlinear I-V equation are implemented in a Fortran code. The graphical user interface provides the users with easy and simple way to modify the PV array parameters and simulation conditions. In order to help the users, this model also provides the parameters of 10 commercial PV arrays.