An Analysis on the VSC-HVDC Contribution for the Static Voltage Stability Margin and Effective Short Circuit Ratio Enhancement in Hybrid Multi-Infeed HVDC Systems

Abstract

Over the years, high voltage transmission of large energy blocks over long distances has widely developed from the Line Commutated Converter (LCC) technology. However, the continuous expansion of the AC network and the increase in renewable energy penetration leads to the weakening of Electric Power Systems (EPS), causing operational problems for the LCC-HVDC. This paper evaluates the degree of contribution of the VSC-HVDC on the LCC-HVDC dynamic performance when the infeed is in a hybrid multi-infeed HVDC system. Through a steady-state mathematical framework, the new concept of Hybrid Power Voltage Interaction Factor (hPVIF) is proposed to assess the transient stability improvement of LCC. Additionally, this article introduces two key contributions from hPVIF: the complementary Improved Commutation Failure Immunity Index (iCFII), as a measure of the effective short circuit enhancement, as well as the apparent line length, which emulates the line lengths adjusting the power dispatch in the VSC-HVDC. PSCAD/EMTDCTM time-domain dynamic simulations are performed to assess the indexes, and the Matlab® software will be used to assist in mathematical operations.

Hybrid Multi-Infeed Interaction Factor Calculation Method Considering Voltage Regulation Control Characteristics of Voltage Source Converter

“…With the construction of VSC-HVDC projects, the situation gradually increases that VSC-HVDC is fed into the original MIDC system, and then a hybrid multiinfeed high voltage direct current system (HMIDC) is formed. The receiving-end power grid will show new operating characteristics due to the complex interactions among multiple inverters of different types [8][9][10]. The research on the interaction of multiple inverters in MIDC and HMIDC is of great significance for the planning and operation of the receiving-end power grid.…”

Determination Method of Cascaded Number for Lumped Parameter Models Oriented to Transmission Lines

“…Due to the low operating frequency and short transmission distance, the wavelength of the voltage is so small that it can be ignored. For the network with high frequency and long lines [10][11], such as high voltage direct current and half-wavelength AC transmission, the wavelength of the voltage accounts for a large proportion of the length of the transmission line [12][13][14]. Equivalent LPMs of these systems have significant errors.…”