| Energy is power to push society development. At present, the energy structure is composed of non-renewable resources. With the decreasing of non-renewable resource and the ecological environment problem becoming more and more serious, renewable energy gets more and more attention. Solar energy is an abundant renewable energy, which is mainly used by photovoltaic power generation inverter. In order to high efficiency usage of solar energy, the power generation efficiency has already been pursuing. And the transformerless grid-connected inverter is warmly welcoming. At the same time, the reliable performance and safety requirement should be paied much more attention. High-performance photovoltaic (PV) monitoring system is increasing becoming important in the PV power generation. Because it can not only solve the problem of maintenance and achieve realtime monitoring but also can improve the safety and reliability of power system operation. Under the circumstance of smart grid application, the monitoring system can promote the implement of power dispatching.This paper studies the Photovoltaic grid connected inverter, taking the H6-bridge inverter as the main topology structure of photovoltaic inverter. The system control strategies of inverter are studied, and the current loop is taken as the inner loop and the voltage loop as the outer loop. This double loop control can keep the DC bus voltage constant and guarantee the power generation quality, and achieve a dynamic matching of energy as well. The control to output transformation function has been deduced and on this basis the control parameters desigened. In order to make current phase tracking down phase of grid voltage, the phase locked loop has been designed to realize the active power output of the system. Additionally, a kind of islanding detection method based on frequency perturbation has been discussed in detail.The photovoltaic monitoring system is also explored and designed in this paper. This monitoring system has two layers of architecture, i.e., on-site monitoring layer and remote monitoring layer. Among them the site monitoring layer employs TMS320F2808as the main controller, LPC1768as the slave controller. The LCD display module, keypad module and communication module are designed; on the other hand, the remote monitoring layer monitors the running state of inverter with the help of the GUI developed by C#language. The GUI software of monitoring system consists of interface display, real-time communication and data storage. Field control layer and remote control layer takes RS485as the communication Bus and Modbus protocol as the communication protocol to implement the reliable transmission of remote data. Base on the above research, this paper elaborate a power management unit, which on the monitoring system basis, can make the paralleling set control the reactive power dispatch well.The study on the designments of H6-type inverter’s mian paramerters and control has been conducted by Psim software simulation. And a4.6KW transformerless single-phase photovoltaic inverter is developed as experimental prototype, and its monitoring system also configured. Experiments have been done to verify the design method of transformerless PV single-phase inverter and the reliability of the monitoring system. |
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