Inverters are the "brain" and "heart" of photovoltaic power generation.
Time:2024-08-02
Views:112
Photovoltaic inverter is a power electronic conversion device that connects solar panels and the grid, and its main function is to convert the direct current generated by solar panels into alternating current that can be connected to the grid through a power module.From the point of view of the necessity of inverters, photovoltaic arrays can generate electricity as DC, but DC power supply system has a big limitation, it is not easy to change the voltage and the range of application of the loads is very limited, inverters can be used to convert the DC generated by the panels into the alternating current (AC) power needed for life.
According to the technical route, PV inverters can be broadly classified into four categories: centralised inverters, string inverters, hub-and-spoke PV inverters and micro-inverters.
1) Centralised inverter: generally used in large-scale power generation systems such as large-scale plants with uniform sunshine, desert power stations, ground power stations, etc., and the total power of the system is generally above the MW level, the advantage of which lies in the fact that the number of inverters in the power station using centralised inverter is small, which is easy to manage, and the degree of integration is high, the power density is high, the cost is low, and the disadvantage is mainly the narrow voltage range of the MPPT, which is generally 450-820V, and the configuration of the components is not flexible.Short power generation time in rainy and foggy ministries and districts:The system is complicated to maintain and occupies a large area.
2) String inverter: mainly used for distributed and small ground power station, each PV string (1-5kw) through an inverter, in the DC terminal with maximum power peak tracking, the advantage is not subject to the module differences between the group Shen, and the impact of the sun and shadow shading, and at the same time to reduce the PV module optimal operating point and the inverter does not match the case of the maximum increase in power generation; small size, light weight, handling and installation are very convenient.
3) Collective PV inverter: It is suitable for medium-sized PV power station, which can be flexibly configured according to the actual demand, with high efficiency and reliability, and at the same time with good economic benefits.
4) Microinverter: able to achieve maximum power point tracking at the panel level, through the optimisation of the output power of each module, so that the overall output power is maximised, when one or even more modules fail, the system can still continue to provide power to the grid, high availability, and effectively reduce the impact of shadows caused by local shading on the output power, but the price is much higher than the centralised and string-type
Energy storage converter is a bi-directional current controllable conversion device connecting the energy storage battery system and the power grid/load, the core function is to control the charging and discharging process of the energy storage battery, and carry out the conversion of AC and DC, so that it can directly supply power to the AC load in the case of no power grid.There are three main modes of operation for PCs: grid-connected and off-grid and hybrid mode:1)In grid-connected mode, the PCS achieves bidirectional energy conversion between the storage battery and the grid, and its main function is to carry out constant-power or constant-current control according to the microgrid monitoring commands, charging or discharging the battery while smoothing out the outputs of the wind power and photovoltaic, etc., which have a high degree of fluctuation.2)In the off-grid mode, the PCS can, according to the actual demand, supply AC energy to the local part of the load to provide AC energy that meets the power quality requirements of the grid.3) In the hybrid mode, the energy storage PCS is able to switch between the well-grid mode and the off-grid mode.
According to the technical route, PV inverters can be broadly classified into four categories: centralised inverters, string inverters, hub-and-spoke PV inverters and micro-inverters.
1) Centralised inverter: generally used in large-scale power generation systems such as large-scale plants with uniform sunshine, desert power stations, ground power stations, etc., and the total power of the system is generally above the MW level, the advantage of which lies in the fact that the number of inverters in the power station using centralised inverter is small, which is easy to manage, and the degree of integration is high, the power density is high, the cost is low, and the disadvantage is mainly the narrow voltage range of the MPPT, which is generally 450-820V, and the configuration of the components is not flexible.Short power generation time in rainy and foggy ministries and districts:The system is complicated to maintain and occupies a large area.
2) String inverter: mainly used for distributed and small ground power station, each PV string (1-5kw) through an inverter, in the DC terminal with maximum power peak tracking, the advantage is not subject to the module differences between the group Shen, and the impact of the sun and shadow shading, and at the same time to reduce the PV module optimal operating point and the inverter does not match the case of the maximum increase in power generation; small size, light weight, handling and installation are very convenient.
3) Collective PV inverter: It is suitable for medium-sized PV power station, which can be flexibly configured according to the actual demand, with high efficiency and reliability, and at the same time with good economic benefits.
4) Microinverter: able to achieve maximum power point tracking at the panel level, through the optimisation of the output power of each module, so that the overall output power is maximised, when one or even more modules fail, the system can still continue to provide power to the grid, high availability, and effectively reduce the impact of shadows caused by local shading on the output power, but the price is much higher than the centralised and string-type
Energy storage converter is a bi-directional current controllable conversion device connecting the energy storage battery system and the power grid/load, the core function is to control the charging and discharging process of the energy storage battery, and carry out the conversion of AC and DC, so that it can directly supply power to the AC load in the case of no power grid.There are three main modes of operation for PCs: grid-connected and off-grid and hybrid mode:1)In grid-connected mode, the PCS achieves bidirectional energy conversion between the storage battery and the grid, and its main function is to carry out constant-power or constant-current control according to the microgrid monitoring commands, charging or discharging the battery while smoothing out the outputs of the wind power and photovoltaic, etc., which have a high degree of fluctuation.2)In the off-grid mode, the PCS can, according to the actual demand, supply AC energy to the local part of the load to provide AC energy that meets the power quality requirements of the grid.3) In the hybrid mode, the energy storage PCS is able to switch between the well-grid mode and the off-grid mode.
Patrick Qi
Patrick Qi
Gitenno