Resonance Suppression Based on PR Control for Single-Phase Grid-Connected Inverters With Filters

Abstract

This paper proposes a novel resonance suppression scheme for a single-phase grid inverter with the LLCL filters. In the structure of the LLCL filters, a small inductor is added in series with the capacitor in the conventional LCL filters to make zero impedance at the switching frequency, by which the grid-side inductor filter can be reduced remarkably. However, a resonance phenomenon is still a critical issue in this system. So, an active damping method based on the proportional and resonant controllers is proposed to suppress the resonance. In addition, the stability is analyzed for the feasibility of the proposed algorithm. Finally, the simulation and experimental results have verified the control algorithm for a single-phase grid inverter.

H∞ Repetitive Control Based on Active Damping with Reduced Computation Delay for LCL-Type Grid-Connected Inverters

“…However, according to Figure 9b, |H(e jωT s )| in this case is greater than unity, and ||H(e jωT s )|| ∞ = 1.9577, which does not satisfy the inequality Equation (17). As a result, the system is unstable.…”

“…and ||H(e jωTs )||∞ = 1.9577, which does not satisfy the inequality Equation (17). As a result, the system is unstable.…”

Stability Analysis of Current Control based on Virtual Resistor for Single-Phase Grid Converters with LLCL Input Filters

“…이에 비해 능동댐핑 제어는 제어 알고리즘의 추가에 의해 공진을 억제할 수 있으므로 수동댐핑 기법의 문제 점을 해결할 수 있으나 제어 알고리즘이 복잡하다는 단 점이 있다 [5], [8]- [14] . PR (Proportional and Resonant) 제어기 기반의 능동 댐핑제어 기법 [8], [9] 은 대역통과필터(Band-pass filter)를 이용하여 계통측 전류에서 공진 성분을 추출한 뒤, PR 제어기를 이용하여 공진 현상을 제거하는 방식이다. 그 러나 계통의 임피던스 변동으로 인해 공진 주파수가 변 할 경우 실시간으로 이를 추정하여 필터의 대역폭을 수 정해야 하는 번거로움이 있다.…”

A Current Decoupling Control Scheme for LCL-Type Single-Phase Grid-Connected Converter

“…Hence, different control schemes are presented. These control schemes can be categorized into four major classes, namely, proportional-resonant (PR) control schemes [6], [7], direct power control (DPC) schemes [11], [12], current control schemes [13], [14] and active damping control [15], [16]. Although a sinusoidal reference signal can effectively be tracked with PR control schemes and the coupling problem caused by coordinate transformation is avoided, the independent control of active current and reactive current cannot be realized and it is difficult to satisfy the reactive power requirement for voltage support when the fault occurs in the power grid.…”