Test specification for impedance characteristics of power supply equipment in information system

Technical specifications for connecting the power quality monitoring device of the medium and low voltage distribution to the IoT platform

Abstract—Offshore wind farms connected with HVDC transmission line is a promising solution to bring the power to shore and assure the system efficiency. A DC-DC converter with high step ratio is required for such application. The modular multilevel converter (MMC) for transformer-less DC-DC converter application is regarded as an alternative solution to replace the two-stage DC-AC-DC conversion. A hybrid multiport modular multilevel DC-DC converter is proposed in this paper, which have one high voltage port and multiple low voltage ports. The low voltage ports can be connected to the dc output of wind turbines. The bidirectional power flow is realized by controlling the arm voltages. The proposed converter has a lower circulating currents as compared to the single-port MMC DC-DC converter. By using the full bridge submodules (FBSMs), the converter also has DC fault blocking capability. 

Abstract—Modular Multilevel Converter (MMC) is composed by hundreds of sub-modules (SMs). Such a large scale power electronic switches and power nodes will become very difficult to solve in the process of real-time simulation of the electromagnetic transient. These switches will occupy a very large amount of calculation, in this case, still use a large step (microsecond) simulation has been unable to meet the sub-module operation during dynamic  response, especially when a short circuit fault occurs in the bridge arm, the electromagnetic transient process of the system cannot be accurately reflected. In order to solve the problem, this paper presents a simplified sub-module model and an equivalent valve model based on state-space node solver implemented in FPGA for the real-time simulation. This method can effectively reduce the power nodes and decrease the computation time, and improves the accuracy of the simulation. In addition, the multi-rate simulation of RT-LAB and the test method of hardware-in-the-loop (HIL) are explained in this paper. Finally the simulation results show that the effectiveness of the proposed method.