Study On Uncertainty Harmonic Power Flow Of Distributed Pv Grid-connected

The distributed PV power generation unit in the distribution network will cause harmonic pollution to the system because of the inverter.In addition,the output power and harmonics of the PV power generation system are random,which brings hidden dangers to the safe operation of the system.Exploring the probability distribution of the system voltage quality index when considering the randomness of PV harmonics is of great significance for evaluating the stability of the system operation.Compare the calculation results of the two to verify the correctness of the program.In this paper,the actual engineering project is taken as an example.According to the network topology structure and system related parameters,the deterministic harmonic power flow calculation is carried out by using ETAP simulation and C++ programming respectively.In the calculation,the harmonic source is set based on the measured data of multiple PV power plants,and the direct decoupling method is adopted.Analyze the calculation results and explore the influence of distributed PV grid-connected on the distribution of harmonic currents in the system.On this basis,a method combining semi-invariant with maximum entropy is proposed to calculate harmonic probability power flow for systems with distributed PV.Write the system harmonic flow equations to monitor the sample's expected value as a reference point and linearize the equations.The measured data of the harmonic currents of the two PV power plants are processed,and the first 4th order semi-invariant is solved;Using the properties of semi-invariants,the semi-invariants of the voltage amplitude and distortion rate of each node are obtained,which is transformed into the original moment.The maximum entropy principle function is used to fit the probability density function of the harmonic voltage amplitude and total distortion of each node of the system and the integral is obtained as a probability distribution function.Finally,the mathematical expectation,variance,95% probability value and other parameters of the harmonic voltage amplitude and distortion rate are obtained,which provides a more suitable reference for the electric operators and PV system designers.