The impact of large-scale photovoltaic and wind power grid connection on the power grid

1. The impact of load peaks and valleys on the power grid

Photovoltaic and wind power grid-connected power generation systems do not have peak regulation and frequency regulation capabilities, which will impact the early peak load and late peak load of the power grid. Because the increased power generation capacity of photovoltaic and wind power grid-connected power generation systems cannot reduce the ownership or redundancy of generator sets in the power system, the power grid must be photovoltaic. The wind power generation system prepares corresponding rotating standby units to solve the peak shaving problem of early peak and late peak. Photovoltaic and wind power grid-connected power generation systems supply power to the grid at the expense of the reduction in unit hours. This is of course not what generators want to see.

2. The influence of day and night changes, time difference between east and west and seasonal changes on the power grid

Due to the periodicity of sunlight and load, the increase of photovoltaic and wind power grid-connected power generation cannot reduce the demand for installed capacity of the grid.

3. The impact of changes in meteorological conditions on the power grid

When the grid-connected power generation of photovoltaic and wind power in a region reaches a certain scale, if the geographical weather changes significantly, the grid will provide enough regional rotating standby units and reactive power compensation capacity for photovoltaic and wind power grid-connected power generation systems to control and adjust. System frequency and voltage. In this case, the power grid will guarantee the safe and stable operation of the power grid at the expense of the economical operation mode.

4. The impact of long-distance photovoltaic power transmission on the power grid

When photovoltaic grid-connected power generation is economically and technically possible to transmit power over long distances, since photovoltaic grid-connected power generation has no rotational inertia, governor and excitation system, it will bring new stability problems to the AC power grid. If the photovoltaic power generation scale is connected to the grid, the use of high voltage AC and DC power transmission will bring stability and economic problems to the adjacent AC system of the photovoltaic power generation and DC power transmission system. Regardless of whether high-voltage AC or DC transmission is used, photovoltaic grid-connected power stations must be equipped with automatic reactive power voltage regulation devices. As for the impact on grid stability, there is no mathematical model for photovoltaic power generation in grid stability calculation. It is not clear how much the photovoltaic well grid power generation will affect the safe and stable operation of the grid.

5. The impact of consumption reduction on the power grid

One of the main advantages of photovoltaic and wind grid power generation is the consumption of alternative fossil fuels. Since photovoltaic and wind power grid-connected power generation increases the rotating standby or hot standby of power plant generators, the actual consumption reduction ratio of photovoltaic and wind power grid-connected power generation should deduct the energy lost by rotating standby units or hot standby units. The consumption reduction efficiency of photovoltaic and wind power grid-connected power generation should take into account the efficiency loss caused by the reduction in the utilization hours of generator sets due to the power provided by the photovoltaic and wind power grid-connected power generation systems. Since the power system operates as a whole, the grid-connected photovoltaic and wind power generation will infringe the interests of other power generators. This is a problem that government planners need to consider. Not only the hydropower plant should serve as a rotating reserve, but the power grid should also be stable when considering safety, stability and economical operation. Therefore, the theoretical coal consumption reduction equivalent to the total photovoltaic and wind power grid-connected power generation in the system should be multiplied by a coefficient less than 1, and the plant power loss of the rotating standby unit should be subtracted in equal proportion.

Therefore, in the process of developing solar and wind energy resources, it is very necessary for the power grid to carry out new energy planning. The task of new energy development planning is to study the scale and speed of long-term development of new energy. Scope Based on the development of the future national economy, with natural resources and other economic resources as the conditions, the user's demand for electricity and electricity is measured, and then certain guidance and assistance for economic development are provided.

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