# A Review of Distribution Grid Consumption Strategies Containing Distributed Photovoltaics
## 3 Distribution Grid Consumption Strategy with Distributed PV
### Voltage Control Strategies for Distribution Grids Containing Distributed Photovoltaics  
#### 3.3.1 Voltage Control using PV Inverters  
Distributed PV power access will change the grid structure, and when high-penetration PV power access is provided, it may exceed the dissipation capacity of the distribution grid, resulting in the active and reactive power balance of the power system being broken, which in turn affects the stability of the grid voltage and frequency. Therefore, the voltage overrun problem of distributed PV access also belongs to the consumption problem. The PV inverter is one of the very key devices in the grid-connected PV system, which can realize the inverter function of DC power through the control of power electronic switches, thus ensuring that the PV power meets the requirements of grid-connected. Some inverters also integrate functions such as maximum power point tracking to further improve the reliability and stability of the grid-connected system [83]. The topology of one of the PV inverters is shown in Figure 10 [84]. Figure 10: Topology of PV inverter network. In view of the key role of PV inverters, it is possible to formulate a scheme for PV inverters to participate in the reactive voltage control of the grid [85; 86; 87], utilizing the principle of absorbing and releasing reactive power by PV inverters, using external inverters to achieve filtering function and joining reactive power compensation devices to achieve the absorption of reactive power, which effectively improves the quality of electric power. The PV inverter is used to realize the regulation and control of the grid-connected voltage, and the distributed PV voltage coordination control strategy for traction power supply is proposed considering the reactive power capacity margin of the inverter, which makes full use of the PV's own voltage regulation capability. According to the principle of variable sag control combined with the energy storage system, the voltage stratification control method of PV plus energy storage can be designed. All of the above can make full use of the function of the PV inverter itself, but the common problem is that the inverter extremely easily fails a device; in the case of maximizing the use of its own function, design the corresponding inverter protection methods. In addition to the voltage control function of the PV inverter itself, the PV inverter also has the function of maximum power point tracking (referred to as MPPT) in order to obtain the maximum power output in a variety of situations. At this stage, there are many research methods for the MPPT, but the tracking accuracy is still to be improved because the accuracy can not be improved, so the power of the PV system has the same characteristics as that of the PV system. Because the accuracy cannot be improved, the power of the PV system has a considerable loss. Therefore, the MPPT technology for PV systems should be studied in depth in the future. The structure of the PV MPPT system is shown in Figure 11[88]. In order to improve the accuracy of PV MPPT, various researchers have also carried out optimization studies from various aspects, and the theoretical accuracy is indeed significantly improved, but whether it can be applied to the actual is still to be tested. Through intelligent algorithms [89; 90; 91; 92] to improve the accuracy of tracking, the application of intelligent algorithms is mostly similar to those summarized in energy storage; various types of intelligent algorithms for different defects, after the optimization of algorithms, have to reduce the search range, there is a change in the perturbation mechanism, and also to improve the dynamic performance of the optimization of the PV MPPT from a variety of perspectives to provide ideas.