Design and Evaluation of a Photovoltaic Inverter with Grid-Tracking and Grid-Forming Controls [2, 3], and, subsequently, inverters'' operation, the initial frequency regulation during grid
1 Introduction. Among the most advanced forms of power generation technology, photovoltaic (PV) power generation is becoming the most effective and realistic way to solve environmental and energy problems
An important technique to address the issue of stability and reliability of PV systems is optimizing converters'' control. Power converters'' control is intricate and affects the overall stability of the system because of the
This paper investigates the voltage and frequency stability problems in PV systems connected with weak power grids. The voltage problems caused by grid impedance, comprising inverter AC voltage and DC voltage,
The installation of photovoltaic (PV) system for electrical power generation has gained a substantial interest in the power system for clean and green energy. However, having the intermittent characteristics of photovoltaic,
When the inverter operates at lower power, the switching loss of the power device is no longer a limiting factor. Therefore, increasing the switching frequency of the power device according to certain constraints as the output power is reduced helps to reduce the harmonic content of the grid current and improve the grid-connected power quality.
The role of reactive power control in a PV inverter, as suggested by the authors in [research paper], is to mitigate distribution system voltage magnitude fluctuations caused by short-term solar power fluctuation. Reactive power control for PV inverters improves distribution system operation.
According to the previous analysis, the increase of the PV inverter output power may cause PV output voltage to contain high order harmonics under the weak grid, which are mainly distributed near the resonance peak of output filter LCL of PV inverter.
With increasing the PV output power, the maximum harmonic amplification coefficient in the low frequency band also grows to 1.228. Meanwhile, with the output power grows, the PV inverter causes harmonic amplification in PCC voltage.
The coupling of PV inverters connected to the grid through phase-locked loops (PLL) and voltage-current controllers is enhanced in the case of a weak grid. This in turn, brings a series of wide-frequency domain multi-timescale stability problems to the operation of large-scale power plants .
Nevertheless, as the capacity of the photovoltaic plant increases and begins to represent a considerable part of the energy produced, problems of grid quality, such as harmonics, frequency fluctuation, voltage violations, inverted power flow and poor coordination of grid protection equipment may occur .
