Real time parameter estimation for power quality control and intelligent protection of grid-connected power electronic converters

This paper presents a method to identify power system impedance in real-time using signals obtained from grid- connected power electronic converters. The proposed impedance estimation has potential applications in renewable/distributed energy systems, STATCOM, and solid state substations. The method uses wavelets to analyze transients associated with small disturbances imposed by power converters and determine the net impedance back to the source. A data capture period of 5ms is applied to an accurate impedance estimation which provides the possibility of ultra fast fault detection (i.e. within a half cycle). The paper describes how the proposed method would enhance the distributed generation operation during faults

Grid impedance estimation for islanding detection and adaptive control of converters

The grid impedance is time varying due to the changing structure of the power system configuration and it can have a considerable influence on the control and stability of grid connected converters. This paper presents an online grid impedance estimation method using the output switching current ripple of a SVPWM based grid connected converter. The proposed impedance estimation method is derived from the discretised system model using two consecutive samples within the switching period. The estimated impedance is used for islanding detection and online current controller parameter adaptation. Theoretical analysis and MATLAB simulation results are presented to verify the proposed method. The effectiveness of the grid impedance estimator is validated using experimental results

Real time parameter estimation for power quality control and intelligent protection of grid-connected power electronic converters

none4This paper presents a method to identify power system impedance in real-time using signals obtained from grid- connected power electronic converters. The proposed impedance estimation has potential applications in renewable/distributed energy systems, STATCOM, and solid state substations. The method uses wavelets to analyze transients associated with small disturbances imposed by power converters and determine the net impedance back to the source. A data capture period of 5 ms is applied to an accurate impedance estimation which provides the possibility of ultra fast fault detection (i.e., within a half cycle). The paper describes how the proposed method would enhance the distributed generation operation during faults. © 2014 IEEE.noneSumner M., Abusorrah A., Thomas D., Zanchetta P.Sumner, M.; Abusorrah, A.; Thomas, D.; Zanchetta, P

Real Time Testing and Validation of a Novel Short Circuit Current (SCC) Controller for a Photovoltaic Inverter

About 45% applications from PV solar farm developers seeking connections to the distribution grids in Ontario were denied in 2011-13 as the short circuit current (SCC) capacity of several distribution substations had already been reached. PV solar system inverters typically contribute 1.2 p.u. to 1.8 p.u. fault current which was not considered acceptable by utility companies due to the need for very expensive protective breaker upgrades. Since then, this cause has become a major impediment in the growth of PV based renewable systems in Ontario. A novel predictive technique has been patented in our research group for management of short circuit current contribution from PV inverters to ensure effective deployment of solar farms. This thesis deals with the real time testing and validation of a short circuit current (SCC) controller based on the above technique. With this SCC controller, the PV inverter can be shut off within 1-2 milliseconds from the initiation of any fault in the grid that can cause the short circuit current to exceed the rated current of the inverter. Therefore, the power system does not see any short circuit current contribution from the PV inverter and no expensive upgrades in protective breakers are required in the system. The performance of the PV solar system with the short circuit current controller is simulated and tested using (i) industry grade electromagnetic transients software PSCAD/EMTDC (ii) real time simulation studies on the Real Time Digital Simulator (RTDS) (iii) physical implementation on dSPACE board to generate firing pulses for the inverter. The validation of controller is done on dSPACE board with actual PV inverter short circuit waveforms obtained from Southern California Edison Short Circuit Testing Lab. This novel technology is planned to be showcased on a physical 10 kW PV solar system in Bluewater Power Distribution Corporation, Sarnia, Ontario. This proposed technology is expected to remove the technical hurdles which caused the denials of connectivity to several PV solar farms, and effectively lead to greater connections of PV solar farms in Ontario and in similar jurisdictions, worldwide