Analysis and solution of power quality problems caused by high proportion of new energy grid
The National Government Work Report for 2024 proposes to actively and steadily promote the "carbon peak, carbon neutrality" and solidly carry out the "Ten actions to reach the carbon peak", further promote the energy revolution to control fossil energy consumption, accelerate the construction of new energy systems, strengthen the construction of large wind power photovoltaic bases and delivery channels, promote the development and utilization of distributed energy and develop new energy storage. Promote the use of green electricity and international mutual recognition to play the role of coal and coal power to ensure energy demand for economic and social development.
1.High proportion of new energy grid features
Comparison of new and old power grid characteristics
(1) Traditional power grid
Thermal power, hydropower and other traditional units using synchronous motor, with strong mechanical inertia, power system has a large time constant, short circuit capacity.
The power generation of traditional power grid is stable and controllable.
The traditional power grid transmission mainly AC high-voltage lines.
The traditional power grid load is mainly motor, metallurgy, residential electricity, the main power quality problems are reactive power, low harmonic, flicker, imbalance and so on. The frequency of harmonics is relatively fixed, which is related to the rectification mode.
(2) New-type power grid
The new power grid introduces more power electronic equipment in the source-network-load end, and the power system shows significant power electronization. It presents the characteristics of low inertia, low short-circuit capacity and weak immunity, which makes the time constant of the power system smaller (millisecond level), the frequency domain wider (hundreds of Hertz), and the stability is worse.
The power generation of the new power grid is affected by natural factors, and the power generation is unstable and has large time variability.
New power grid transmission, HVDC transmission, flexible governance transmission, AC, DC transmission to build a highly flexible power grid.
The new power grid shows significant power electronization, harmonic problems are complex, low-frequency oscillation (below the fundamental wave), sub-synchronous oscillation, high-order ultra-high-order harmonics (tens of KHz).
2.Power quality issues change
Power quality problem of traditional power grid
The fundamental cause of harmonic generation in power system is due to nonlinear load. The nonlinear load in the traditional power grid is mainly diode rectifier circuit or thyristor phase controlled rectifier circuit, and various arc furnaces.
Power quality problem of new power grid
The harmonic problems of new power grid are complicated, and the power quality problems such as high frequency harmonic, sub-synchronous oscillation, low frequency oscillation and interharmonic are prominent.
3.Problem solving approach
Traditional power quality problem solving method
Through: FC passive filter, active power filter (APF), static reactive power compensation device (SVC), static reactive power generator (SVG), dynamic voltage restorer (DVR).
Power quality problem of new power grid
Through: new energy storage equipment, synchronous modulation camera, stationary synchronous modulation camera, grid energy storage converter.
4.Some research of FGI on networking
Grid type high voltage level energy reserve technology
The development of FGI level federal energy system, and the introduction of level federal energy virtual synchro algorithm for network construction algorithm. External characteristics meet the characteristics of the adjusting camera, with frequency regulation, pressure regulation, inertia and damping functions, to ensure the stable operation of the point system.
Networked high voltage cascaded SVG
Based on the company's existing high-voltage cascaded SVG, the network control algorithm of high-voltage cascaded SVG is developed, and the power synchronization strategy similar to that of synchronous generator is adopted, combined with the supercapacitor energy storage technology, to realize the active perception and active support of the power grid.
Over the years, FGI has been deeply engaged in product research and development, constantly breaking through technical barriers, and is committed to building a more efficient, intelligent and green new power grid system, effectively improving the stability, reliability and security of the power grid, and contributing to promoting the transformation and upgrading of the energy structure and sustainable development.
Power electronics technology is profoundly changing the global energy system, and will gradually spread to every corner of the world! We have always been based on power electronics technology, diligently and constantly explore to provide customers in the power, industrial and infrastructure fields with solutions and services covering the whole value chain and the whole life cycle. We have always been committed to the construction of new power systems to accelerate energy transformation through digitalization, help achieve carbon neutrality, and jointly create a better future for mankind.
