Analytical Assessment of DC Components Generated by Renewable Energy Resources with Inverter-Based Interconnection System due to Even Harmonics

Abstract

This paper deals with the assessment of DC components generated by renewable energy resources with inverter-based interconnection system to the electric grid. DC injection is a critical issue related to power quality of distribution network systems with high penetration of inverter-based interconnection systems. This type of interface systems may improve the performance of the electric generation unit and affect positively or negatively the power quality of the distribution network depending on the proper or improper designation. The investigation of the various causes of DC components and the analytical assessment of their maximum levels are crucial for the proper operation of inverter-based interface systems and the limitation of DC injection. A method based on analytical calculations using a computer software has been implemented for the assessment of DC components contained on an inverter's output voltage when even harmonics are present on the network voltage. Moreover, a simulation package was used to demonstrate the existence of DC components under various conditions. It was proved by the current analysis that the amounts of DC components generated when even harmonics are present on the network voltage can be high under abnormalities on the power grid but they are not considerable under normal operating conditions.

Harmonic Detection for Shunt Active Power Filter Using ADALINE Neural Network

“…For example, the reference current of the individual harmonic current detection process, i * CI H , is achieved by the compensation of the fundamental reactive current i 1q and the harmonic current order 2nd (i h2 ) to order 5th (i h5 ) as shown in Equation (22). Figure 5b shows the reference current calculation for the individual harmonic elimination process.…”

“…Also, nowadays, the renewable energy systems are connected to the main power grid distribution system, resulting in the DC quantity being generated in the power system. This causes problems for transformer and circuit breaker operations [22][23][24][25]. Therefore, SAPF is also essential to have the ability to reduce the DC quantity generated in the power system as well.…”