The contradiction between China’s energy and economic development makes the energy problem become more and more tense, photovoltaic power generation can alleviate this energy pressure to a certain extent. At present, the advanced distributed photovoltaic power generation technology can meet people’s electricity consumption in daily life and work, and ensure that people are better engaged in various activities.
1 Photovoltaic power supply
The photovoltaic power supply is a device that converts solar energy into electricity by using renewable solar energy and using solar panels. Photovoltaic power supplies rely on solar photovoltaic Ford development, the use of solar energy emitted by the heat, and the use of solar energy under the action of the panel to produce electricity. It provides the most effective and sufficient energy supply for people’s work and life. Photovoltaic power supply device is mainly composed of three parts, the three parts are the controller, solar panels, and inverters. The photovoltaic power supply device is the storage and conversion of electric energy under the joint action of these three parts. The use of photovoltaic power supplies has many benefits, its use can not only reduce the harm to the environment but also achieve better electricity effects. For people in remote areas when using electricity, the flexibility of photovoltaic power supplies can use better electrical energy for them. After the photovoltaic power generation starts to be used in the area where it is used, there are many ways to choose to use it, as shown in Figure 1. They can be used independently or in conjunction with other distribution networks. Such strong adaptability can basically meet people’s demand for electric energy. However, due to the different seasons, photovoltaic power supplies will be affected in the process of converting electrical energy, thus hindering the normal operation of the grid. The relevant departments of China’s power grid have put forward normative requirements for the photovoltaic power supply in the process of grid connection, so as to reduce the adverse effects caused by the energy conversion process.
(1) China’s relevant departments require the use of grid-connected power generation, which can reduce the adverse effects caused by the power generation process.
(2) In the operation process of photovoltaic power supply, too much quantity cannot be accessed, because too many photovoltaic power supplies will cause the pressure of the power grid to increase, thus making the pressure of the power grid increase.
(3) The voltage of the photovoltaic power supply in the grid needs to be below 8kV. These specifications require the relevant departments to conduct self-supervision so that photovoltaic power supplies can be better used in the power grid, so as to improve the reliability of photovoltaic power supplies in the use of the process.
2. Impact of grid-connected photovoltaic power generation on power grid operation
2.1 Poor control of power grid operation
The effective use of photovoltaic power supply is of great significance for the increase of people’s living standards and working quality, which also fully reflects the importance of photovoltaic power supply in the process of effective use of electric energy. The use of photovoltaic power generation connected to the grid can realize the effective utilization of solar energy into electric energy. However, with the increase of the scale of grid-connected photovoltaic power generation, once the power supply environment becomes harsh, the relevant staff of the power supply station can not accurately grasp the changing power of the grid; It is also impossible to make an accurate judgment on the increase of electric energy load after large-scale use. The uncontrollability of these two aspects causes the relevant staff to have difficulties in the process of electric energy scheduling. In addition to large-scale use, the staff can not accurately grasp the load and grid power, there are many other uncontrollable factors in the process of solar power generation. For example, when the process of solar power generation is affected by some unstable factors, sometimes large problems will occur under these unstable factors, which will cause serious problems. In this case, the photovoltaic power grid is no longer applicable, The relevant staff need to use traditional means of power generation, so that the rescheduling of power, can not meet people’s normal demand for electricity, and can not ensure people’s normal electricity. After photovoltaic power generation is connected to the grid, the access to photovoltaic power in the grid will increase, and the increase in the number of photovoltaic power supplies will increase the pressure of peak regulation and frequency modulation of the grid, which makes the scheduling process of electric energy significantly affected. At the same time, in the public power grid, the access to photovoltaic power supplies will make the number of photovoltaic power supplies and the application area become larger. In this case, if the power system is not able to control all photovoltaic power supplies, it will cause problems in the power system’s power supply equipment, voltage value, etc., resulting in poor control effects, resulting in safety accidents during the operation of the entire grid.
2.2 Power quality damage
After the photovoltaic power supply is connected to the grid, its operation needs to operate the inverter under high-frequency modulation, but under this mode of operation, it is relatively easy to appear harmonics, harmonics will cause the quality of power to be damaged. If after the harmonic amplification, then for the original grid, its output power will also change accordingly. The output power after the change is more difficult for the staff to regulate, so it is easy to lead to voltage instability of the entire grid, resulting in safety accidents. At the same time, China’s traditional power grid with that supply mode is a single supply, but this is not in line with the situation after photovoltaic power access. After the photovoltaic power supply is connected to the grid, the voltage of the corresponding access point is not the same, so it is necessary to manage the grid after the access to the photovoltaic power supply, which will cause more links that need to be managed. In the above cases, the occurrence of harmonics, the instability of voltage, output power, and the increase of working links will cause power quality damage.
2.3 Island effect
The island effect often occurs after the photovoltaic power supply is connected to the public network. In the operation of the power grid, if there is a failure in the public power grid, then the public power grid can not provide a normal power supply for people, but in the process, photovoltaic power is still a normal power supply. If at the time of failure, timely maintenance and overhaul can not be carried out, photovoltaic power generation is still underway, it will make many people in isolated areas can not get a timely power supply, thus forming an island effect. At the same time, if the maintenance personnel directly carry out the inspection and maintenance of the fault, it is easy to cause safety accidents, if the maintenance is not timely, it will cause insufficient power supply, affecting people’s normal life and work.
3. Improvement strategies for the impact of grid-connected photovoltaic power generation on power grid operation
3.1 Improve the control of the power grid
In view of the poor control of the power grid during operation, the power supply-related units can use photovoltaic power prediction technology to detect the output power after the photovoltaic power supply is integrated into the power grid so that the photovoltaic power supply and other power supplies can realize the output power and voltage supervision in the case of automation, so as to achieve the rationality of power supply scheduling. In order to realize the rationality of power supply dispatching and distribution, the power station should do the following points.
(1) Because the photovoltaic power supply is affected by radiation, light, etc., it is still relatively large. Therefore, in view of this situation, relevant technicians should investigate the light intensity, radiation, and cloud cover of the area where the photovoltaic power supply is connected to the grid, and then use relevant technologies to build a model of photovoltaic power generation. Through the combination of relevant natural conditions and photovoltaic power generation, the law of existence is found, so as to provide relevant data support for the practical application in the later period.
(2) Through the relevant data find the best location to install photovoltaic power supplies, reduce the influence of external factors on photovoltaic power supplies, and improve the stability of photovoltaic power supplies in the application process.
(3) It is necessary to reserve electrical energy. In the process of power generation, there will certainly be power instability, so in this case, it is necessary to use the reserved electric energy to supplement, so as to achieve the stable operation of electric energy and improve the operation efficiency of the grid.
3.2 Improve power quality
If the power supply unit wants to improve the quality of electric energy, it must improve the supervision of electric energy. Relevant personnel can carry out comprehensive power quality management for each photovoltaic power supply access point before connecting to the grid. The power quality is measured by integrated power quality management of access points. In the process of detection, if harmonics or voltage fluctuations are found, the relevant technicians can quickly take measures to strengthen the control of power quality.
3.3 Improve the islanding effect
The method to improve the islanding effect can be detected by means of maintenance. When the power grid is powered off, the passive detection method can be used to detect the relevant parameters of the inverter, so as to find the existing problem, If there is a large gap between the output power and the load power, then there is an island effect. Relevant personnel can also take active detection or a combination of active and passive detection means to find the problem. To solve the island effect, relevant personnel need to repeatedly study the common problems and find the commonality of the problems, so as to effectively prevent the problems and reduce the occurrence of the island effect.
