Research On Stable Operation And Control Of Isolated Hybrid System With Photovoltaic And Li-ion Battery Storage

Abstract:As a renewable forms of electricity generation, today people pay more and more attention to the solar power which is volatile and random in increasingly depleted fossil energy, cause the output power fluctuation, so the voltage and frequency will have a high permeability isolated adversely that affect the power system, which increase the permeability of an impact on PV important factor, resulting in the output of the photovoltaic power generation system that can’t be controlled. One way to solve the problem is to constitute the photovoltaic and li-ion battery storage to together, even use storage technology to improve the controllability of the photovoltaic power generation system, especially in remote mountainous areas and islands.Focus on the PV hybrid system and lithium battery system, using voltage linear compensation rings and frequency droop control and improve control of the hybrid system isolated network stability studies. The paper establish a photovoltaic power generation systems, lithium battery systems (BESS) model to determine the optical storage hybrid system topology. Papers from the control strategy for hybrid energy storage system isolated network stability analysis of the problem, because of its fast response and load dynamic optical characteristics, it can be as large grid similar to "balance node" to maintain the system voltage and frequency stability. BESS not only can create voltage and frequency, and smooth the system for photovoltaic power and load difference between the system of power in order to achieve balance, thus maintain a stable voltage and frequency, load power distribution control system based on battery state of charge of the improved power droop produced after control strategy, because the traditional droop control strategy which led to the system to reach a new steady state public bus voltage and frequency error, the paper contains a linear compensated ring of voltage--frequency (V/f) control, make the AC bus voltage and frequency more stable.Using the MATLAB/SIMULINK software environment, the paper build battery systems that improve droop control the state of charge and analyze linear compensation loop V/f control simulation model, to verify the stability of the control strategy in a public bus voltage and frequency stability, load power correctness and validity of distribution, indicating that the isolated grid of the hybrid system can be stable and reliable operation.