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Technology Roadmap of PV inverters

Date:2014/9/17    Access:2583 Secondary

Before the rise of the photovoltaic industry, inverter or inverter technology has been applied to such major rail transportation, power and other industries. After the rise of the photovoltaic industry, photovoltaic inverter has become a new energy power generation system, the core equipment, followed by everyone familiar with. Especially in the American and European countries, due to popular arts concept of environmental protection, the PV market to carry out early, especially the rapid development of domestic photovoltaic systems in many countries, home inverter has been in use as a household appliance, the penetration rate than the high.
Fed into the PV inverter PV modules produce direct current into alternating current power grid after the inverter performance and reliability determines the power quality and power efficiency power generation, so the entire PV inverter PV system in a central position .
In general, the relationship between the inverter and the grid to classify, photovoltaic inverter will be divided into the following main categories
1. Grid (Grid-connected) inverters
2, off-grid (Solo) inverter
3, bi-directional (Bi-direction) of the inverter
4, micro-grid (Smart grid) inverter
Among them, and inverter occupy a major market share in all categories, but also a beginning of all inverter technology. Compared to other types of inverters, grid inverse primary technically relatively simple, focusing on photovoltaic power input and output, safe, reliable, efficient, high-quality output power has become the focus of this type of inverter technology to measure indicators. PV inverter grid-technical conditions in different countries to develop, more than a few similarities become the standard measure of the point, of course, the details of the parameters are different. For grid-connected inverter, all the technical requirements are around to meet the power requirements of distributed power generation system expanded, more requirements from the grid inverter requirement that top-down requirements, such as voltage, frequency, size, power quality requirements, the occurrence of safety, fault time control requirements, as well as how the grid, the grid, and so what voltage level requirements, so grid inverter is always to meet the requirements of the grid that is can, it does not come from inside the power system requirements, but technically speaking, a very important point is grid-connected inverter is "grid" that is consistent with, and network conditions that generate electricity, it does not bear the grid itself The stability, security and other issues, not related to energy management issues within the PV system. According to statistics from abroad, has built and runs the photovoltaic system, about more than 90% of all PV inverter system, are used in a grid-connected inverter.
And grid inverter opposing a class inverter is off-grid inverter. Off-grid inverter means that the inverter output and the grid is not linked, but the load linked, directly contributing to the load. Off-grid inverter applications is less, mainly in remote areas, do not have and network conditions, and poor network conditions, or a self-generating, self-under electricity demand of the occasion, off-grid systems emphasize that "spontaneous for personal use. " Off-grid inverter is due to fewer applications, so technically research and development are very small. In the international arena on off-grid inverter technical conditions, standards and few, which led to the kind of inverter research and development is less and less, shrinking trend. But off-grid inverter has the function of technology involved is not simple, especially with storage batteries fit. System by other devices off-grid inverter, solar panels, batteries, and other components of the load is already a simple micro-grid system, the only thing is that the system is not associated with the grid, is a "island system."
In fact, off-grid inverter is a basic bi-directional inverter development, bi-directional inverter is actually a combination of grid-connected inverter and the inverter from the technical characteristics of the network, the application of the local power supply network or power systems and grid parallel applications use. Although this type of application is not much, but because the class system is the prototype micro-grid development, in line with the future of distributed power generation infrastructure and commercial operation mode, so technically belong to the past and a role that the current grid inverter bridge between applications and the future between local micro-grid applications. In fact, in a number of PV development faster, more mature countries and markets, micro-grid applications in home, small regional units already begun to slowly develop. Meanwhile, the local government to encourage the development of the family as a unit of local power generation, electricity storage, electricity networks to new energy priority for personal use, and the gap from the grid. Therefore bi-directional inverter consider more control and energy management functions, such as battery charge and discharge control, grid / off-grid operation strategy, load and reliable power supply strategies. Overall, bi-directional inverter will be more from the perspective of the whole system plays an important control and management functions without considering only require a single grid or load requirements.
As one of the direction of grid development, to build new energy at the core of the local power generation, distribution, electricity network will be one of the main ways the future development of the micro-grid. In this mode, the local power grid and micro-grid will form an interactive relationship, microgrid will no longer rely on a large grid operation closely, and more ways to operate independently, that is an island in the run mode. To meet the security zone, reliable electricity priority, only the rich or the local electricity needs to take power from an external power when it formed and network operation mode. Currently, due to the various aspects of technology, policy and other conditions are not ripe, the microgrid has not been applied on a large scale, only a small number of demonstration projects in operation, and these projects, and network operation mode with the majority. Micro-grid inverter is a combination of technical features bi-directional inverter, while playing an important network management functions, is typical of the inverter, control and management of an integrated inverter control one machine. It bears the local energy management, load control, battery management, inverters, protection and other functions, will and micro-grid energy management system (MGEMS) with the completion of the entire micro-grid management functions, will be to build the core equipment microgrid system. And inverter technology in the beginning compared to grid-connected inverter, inverter has been out of pure function, and carries a microgrid management and control functions, concerns and solve some of the problems from the system level

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