Load flow analysis of hybrid AC-DC power system with offshore wind power

Abstract

The offshore wind power has received immense attention because of higher wind speed and lower opposition for construction. A wide range of combinations of high-voltage AC-DC transmission have been proposed for integrating offshore wind farms and long-distance power transmission. This paper is to model such hybrid AC-DC systems including the interfacing converters, which have several control parameters that can change the load flow of the hybrid systems. Then, the paper proposes a Load Flow algorithm based on the Newton-Raphson method, which covers three different section types of the transmission system: the AC parts, the DC parts and the interfacing converters. Finally, this paper validates this algorithm through a detailed case study with a typical hybrid network. Index Terms-Hybrid AC-DC network, Load Flow, Newton-Raphson, Offshore Wind Farm, Voltage Source Converter I.The work was supported by both the "Rammeaftale vedrtitrende udnyttelse af PowerlabDK's facillteter" project and the 'Voltage control on the transmission grid using wind power at other voltage levels (VOLATILE)' project (EU 'ERA-Net Smart Grids Plus').

New Approach of Calculation the Steady State Symmetrical Fault Current for Type 4 Wind Power Plants

“…Step 1: A load flow study is carried out to determine the initial bus voltage magnitudes and phase angles. The VSC Wind turbines bus is typically modeled in power flows as a P-V bus [13]. The other nodes except slack bus are modeled as load buses.…”

“…As shown from Fig. 5, 𝐼𝐼 𝑑𝑑𝑝𝑝𝑚𝑚𝑑𝑑 , and 𝐼𝐼 𝑞𝑞𝑝𝑝𝑚𝑚𝑑𝑑 are the active and reactive current injected from the VSC WT in the control reference frame, then the value of the fault current of the wind turbine in the control reference frame computed by (1), and added to the current vector I in (13).…”