How much do you know about the system application of inverters? Today we mainly talk about this, please see the system application and connection of the inverter shown in Figure 1 below.
(1) An independent off-grid power supply (photovoltaic array or wind turbine) supplies power to the charge controller, then charges the battery pack, and then the battery pack supplies DC power to the inverter (see Figure 1a), and finally the inverter outputs alternating current. The battery pack is the primary input source of the inverter.If you would like to learn more about inverter batteries, please visit Tycorun Battery.
(2) The grid-connected/battery-free power source (photovoltaic array or wind turbine) directly supplies power to the inverter (see Figure 1b). The inverter operates in parallel with the grid and supplies power to the load at the same time. If the output power of the photovoltaic array or wind turbine is greater than the demand of the local load, the excess power is fed into the grid. because of this
The system does not require battery purchase and maintenance costs, so it is a cost-effective solution. In this scheme, a generator can be used as a backup power source.
(3) Grid-connected battery (dual-mode) type The system can operate in parallel with the grid or off-grid (see Figure 1c). The inverter is connected to the battery pack, and if the grid loses power, the inverter can supply power directly to the load. The battery pack can be charged from renewable energy or from the grid. Such systems are often used as backup systems to power critical loads after grid outages.
(4) Hybrid off-grid type In this system, two sets of energy sources such as photovoltaic arrays and wind turbines operate in parallel. Each system provides DC power to the inverter, which then drives the load. The system is so flexible that wind turbines, fuel generators or battery packs can provide most of the power to the load when solar radiation is low, and photovoltaic arrays provide most of the power when solar radiation is strong. This strategy reduces reliance on one system and always has a backup power source. The inverter in the system has multiple paralleled power supplies to provide input.
Each graph in Figure 1 represents a different application. Note the location of the charge controller and inverter in different applications. The inverter is a high-tech device and the core equipment of the system. Inverter design and parameter specifications vary from application to application. The inverter’s software and hardware manage the flow of energy between the grid and other power sources. The most straightforward design is an interactive grid-connected system without batteries. If the designer is unsure about the best inverter for a particular application, the manufacturer should be consulted. Many electrical product suppliers can offer complete systems for specific applications (see Figure 2).
Single-stage string inverter is a common inverter. The term string means that PV modules are connected in series to generate high voltage, and these inverters are rated for DC600V input. Microinverters, high frequency transformer inverters, transformerless inverters, three-phase inverters, and off-grid battery inverters are also used in other common designs.
High frequency transformer inverters are a common choice. The input DC power enters the H-bridge circuit, which produces a high frequency output above 60Hz. The output form is a high-voltage high-frequency PWM square wave. The high-voltage electricity is reduced in voltage by a high-frequency transformer, and then filtered into a sine wave that meets the grid requirements. Compared with the 60Hz transformer with the same rated power, the high-frequency transformer has the characteristics of small size, light weight, easy transportation and installation, and less heat generation.
The circuits in the inverter often interfere (cause noise) with radios, televisions, and telephone equipment, resulting in a hum or hum in the sound heard. To reduce interference, install the inverter close to the battery pack, or coil the cables, or separate the AC cables from the phone and audio lines.
There are many certification requirements for grid-tied interactive inverters, such as UL1741, IEEE1547, and Article 690 of the National Electrical Code. The software programs and algorithms that run in the inverter are critical to meeting these certification requirements. All certifications are listed on the equipment nameplate.
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