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Application of high-power inverter in renewable energy system

Jan 25, 2021

Application of high-power inverter in renewable energy system

 The renewable energy market is rebounding strongly from the global financial crisis. Projects that were previously delayed or stopped have been restarted, and many new projects are being implemented. This climax strongly ignited the demand for renewable energy system components throughout the supply chain, including wind power and photovoltaic inverters.


   Similarly, for photovoltaic power generation, a strong growth of 40% of cumulative photovoltaic installed capacity is expected in 2010. Germany is the largest market, while new markets in Southern Europe, the United States and Asia have also seen good growth-especially in Asia. If the Chinese government approves its domestic photovoltaic growth stimulus plan, the plan is expected to be set to achieve 40GW of installed capacity by 2021 aims.


Trends in inverter topology


   The order volume of standard renewable energy inverters has grown tremendously, exceeding 300%.


   For inverters, a clear trend of power topology is emerging. Among them, in the wind power industry, the new development focus is on permanent magnet synchronous motors (SG) using full-power inverters. This configuration can provide higher overall efficiency, a wider range of available wind speeds, and enable the inverter to adapt to new regulations on the interference behavior of power generation equipment on the grid.


The rated power has been unified. For the shore system, the typical rated power of the new project is between 2MW and 3MW, mainly using water-cooled inverters, using double-fed induction generators (DFIG) and SG applications, air-cooled or water-cooled, the lowest power The point is 1.5MW. The power of offshore applications is stable at 5-6MW, and some pilot applications exceed this level. Although the shift to medium voltage (MV) for offshore systems is a clear trend, many new project developments continue to use parallel low voltage (LV) inverters.


  In solar applications, the power technology trend of grid interconnection systems is usually up to 500kW per inverter, and some ongoing new projects reach more than 1MW.


The maturity of the wind power and solar markets coupled with a strong market recovery has put increasing pressure on inverter suppliers to provide pre-qualified, low-tech risk and flexible enough to be used for a certain rating Off-the-shelf standard inverter for power range. Time to market has become the main driving force, and inverters for renewable energy have become commodity items.


Flexible platform: from 450kW to over 2.5MW


   Now there is a new inverter platform that enables system integrators to obtain an easy-to-use multi-function inverter at any time to meet market demand. SAFESAVE for renewable energy is a high-power three-phase inverter platform, which uses an intelligent power module (IPM) integrated with a heat sink, power supply module, drive and protection sensors/functions, and is used for renewable energy applications.了Optimized. Modular structure, with multiple options for rated power, optional air-cooled or water-cooled, and the ability to connect inverters in parallel, making it available for a wide range of applications, from about 450kW to over 250MW full power systems, such as those with System in SG wind power application.


The basic configuration of the    inverter includes three vertical mechanically mounted half-bridge phase units. Each phase unit contains a cooling plate or heat sink, a DC bus with long-life polypropylene capacitors, AC connections and buffers. The individual phase units are connected together by a low-inductance DC coupling and installed in a sturdy mechanical frame. The inverter group can be connected through a DC bus to realize a complete four-quadrant converter, or the inverters can be connected in parallel to obtain a larger rated power.


   Air-cooled and water-cooled versions are available. Both versions use the same overall mechanical structure for configuration. Users can choose between two solutions, one is a simple air-cooled solution that is usually used in solar applications and low-power doubly-fed wind power applications, and the other is a more powerful one that is usually used in larger SG wind power applications. Water cooling solution.


   For renewable energy, the versatility of SAFESAVE is reflected in the realization of the following applications. A typical 1.5MW double-fed system can be easily formed by combining two air-cooled SAFESAVE inverters into a four-quadrant configuration. The complete inverter can be installed in a 600mm wide cabinet. The height is only 1200mm, so that the entire assembly can be installed in a standard 2000mm cabinet and reserve space for other equipment.


  The water-cooled version has two chassis sizes to choose from, and the water-cooled version can achieve greater rated power. The larger 4/3 chassis can accommodate four bays. In a four-quadrant configuration, it is possible to combine four-bay and three-bay assemblies. This allows the module to be optimized, as the requirements for generator-side inverters are often stricter than those on the grid side. The 4/3 chassis can accommodate 1.5MW or 2.5MW full power applications with two inverters in parallel. SAFESAVE has a power density of 10kVA/liter, which has at least a 20% advantage over its closest competitors. The smaller 3/2 chassis uses three brackets for lower power requirements. It is usually used in DFIG systems where the inverter rated power is about 30% of the system power, and high-power solar systems.


  Each inverter only needs two cooling circuit water connectors, because independent cooling plates are connected in parallel to avoid heat accumulation. Two quick connectors for outlet and inlet are located at the bottom of each inverter to facilitate the connection with the external cooling system.


feature design


   Due to the functional design of the SAFESAVE platform for renewable energy, the components can be easily connected together at the DC bus through a low-inductance bus that couples between the components. This makes it easy to configure four-quadrant applications and parallel inverters to obtain more power. In addition, by using another SAFESAVE component, a brake chopper can be added. This flexibility allows system integrators to easily use the same components to build a series of products with different power ratings. As a standard configuration, a simple AC bus is provided to facilitate the cable connection at the front of the inverter assembly, or an AC bus kit can be purchased to locate the AC connection at the bottom of each inverter assembly.


Benefits for the renewable energy market


   Inverter system suppliers can benefit from being able to outsource a SAFESAVE standard product for renewable energy. System suppliers can now freely choose qualified models without expensive investment in design and manufacturing resources, and can minimize technical risks. The flexibility and functional design of the SAFESAVE product series adds another dimension to the supply chain, enabling system suppliers to meet the prevailing market demand for short time to market.