On Resonances and Harmonics in HVDCMMC Station Connected to AC grid

Abstract

Resonance and harmonic phenomena can occur when HVDC and FACTS devices are inserted into AC grids. Frequency response analysis and EMT-type simulations of converter stations are essential for analyzing and preventing negative effects. This paper presents two approaches for deriving the high frequency response of a converter station: using simplified analytical representation and accurate EMT-type model. Validations with control parameter impacts are presented. This paper also presents a test case, based on a recent HVDC project, where potential resonances can occur between the converter station and its AC network. It is demonstrated analytically that these resonances are mainly due to control system parameters and AC network configurations.

Existing System

DQ Model.

Proposed System

In this paper, the derivation of the frequency response of a MMC station based on a black-box EMT model is also presented. It provides the mathematical development to identify the harmonic source injections in EMT tools. Several test cases are simulated, to analysis the accuracy limitations of the simple analytical model against a detailed EMT-type HVDC-MMC link model. In addition, this paper presents a new issue that can lead to high frequency resonances due to the interaction between a control system and AC grid. A realistic test case based on existing HVDC project, is used to validate these resonance phenomena.

Architecture

EMT model setup to derive the equivalent Norton circuit

Compute Norton equivalent of EMT-model