High permeability new energy power grid connection system and stability control method

Abstract

The invention discloses a high permeability new energy power grid connection system and stability control method which belongs to the field of a new energy power system. When new energy has high permeability (50% to 100%), a power grid connection system is composed of a prime mover, a motor and a synchronous generator, or is composed of a motor and a synchronous generator. Rotors of the units are coaxially connected. New energy power is transmitted and converted to power the motor. According to the invention, the method is different from a traditional new energy direct grid connection method; a high permeability new energy power system has enough inertia; the frequency stability of the system is improved; the synchronous generator is retained to effectively damp system oscillation; through voltage and reactive power control, the power angle and the voltage stability of the system are improved; the peaking capacity of traditional thermal power and hydropower units and the like is retained; and through coordinated control of the motor, the synchronous generator and the prime mover, the dynamic regulation characteristic of the system is improved.

Description

technical field [0001] The invention belongs to the technical field of new energy power systems, and in particular relates to a high-permeability new energy power grid-connected system and a stability control method. Background technique [0002] Due to the increasingly serious environmental problems brought about by traditional fossil energy and the depletion of traditional fossil energy in the future, new energy power such as wind power and solar power has become the development direction of today's energy and power field with its unique advantages. The proportion of new energy power connected to the grid has greatly increased in recent years. In Europe, Germany plans to account for 20% of the total power generation in 2020 and 50% in 2050. [1] ;Denmark's wind power output reached 13% of the country's output in 2002, and it is planned to reach 50% of this indicator by 2030; 30%, and the states have also successively proposed 100% new energy grid-connected roadmap plans; i...

AI Technical Summary

Problems solved by technology

[0022] 2) As the number of synchronous generators is greatly reduced or almost zero, the control capability of power system power angle stability that relies on its excitation system will no longer exist, which will give nearly 100% new energy access to the power grid. The problem of angular stability poses great challenges;

[0023] 3) As the number of synchronous generators is greatly reduced or almost zero, the ability to control the voltage stability of the power system based on its excitation system will no longer exist. The process consumes a large amount of reactive power, which leads to more prominent voltage stability problems. Although the doubly-fed induction generator (DFIG) is widely used for its reactive power and voltage regulation capabilities, due to the limitation of its own converter capacity, its The voltage control ability cannot achieve the effect of synchronous generator set

When the voltage control demand exceeds the control capability of DFIG, the grid voltage stability will still be affected [6] ;

[0024] 4) Due to the reduction of synchronous generator sets, its total peak-shaving capability is greatly weakened, or almost zero, which makes power balance a difficult problem

[0026] Although people are discussing and researching large-scale energy storage technology and its possibility of stable operation for high-penetration new energy power systems, it is foreseeable that there is still a lot to be done for the mature and safe operation of large-scale energy storage systems. Solved technical problems

[0027] Therefore, if image 3 As shown in the grid with nearly 100% new energy access, the grid is approximately a zero-inertia system, resulting in the power system’s ability to maintain frequency stability, power angle stability, voltage stability, and peak-shaving operation are greatly weakened, and the reliability of the new energy power system operation Greatly reduced

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