Modeling of HVDC System to Improve Estimation of Transient DC Current and Voltages for AC Line-to-Ground Fault—An Actual Case Study in Korea

Abstract

Abstract:A new modeling method for high voltage direct current (HVDC) systems and associated controllers is presented for the power system simulator for engineering (PSS/E) simulation environment. The aim is to improve the estimation of the transient DC voltage and current in the event of an AC line-to-ground fault. The proposed method consists primary of three interconnected modules for (a) equation conversion; (b) control-mode selection; and (c) DC-line modeling. Simulation case studies were carried out using PSS/E and a power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) model of the Jeju-Haenam HVDC system in Korea. The simulation results are compared with actual operational data and the PSCAD/EMTDC simulation results for an HVDC system during single-phase and three-phase line-to-ground faults, respectively. These comparisons show that the proposed PSS/E modeling method results in the improved estimation of the dynamic variation in the DC voltage and current in the event of an AC network fault, with significant gains in computational efficiency, making it suitable for real-time analysis of HVDC systems.

A Frequency–Power Droop Coefficient Determination Method of Mixed Line-Commutated and Voltage-Sourced Converter Multi-Infeed, High-Voltage, Direct Current Systems: An Actual Case Study in Korea

“…In this section, we formulate an optimization problem to determine the operating points of multiple HVDCs, including LCC and VSC HVDCs. This study is different from previous studies covering various type of HVDCs [22][23][24][25]27], because HVDCs can be regarded as active and reactive power sources in MIDC systems. Also, only the outputs of multiple HVDCs are considered in the optimization problem.…”

“…A common method used to satisfy the power balance between generation and load caused by the forecasting error is frequency-power droop control [21]. Similar to conventional generators, HVDC systems also adopt frequency-power droop controllers [22][23][24]. For economic operation of power systems during frequency control, the calculation of droop coefficients is a significant issue, and the coefficients are used to exploit multiple HVDC systems efficiently.…”

Modeling and Analysis of an LCC HVDC System Using DC Voltage Control to Improve Transient Response and Short-Term Power Transfer Capability

“…Furthermore, Table I lists the parameters used for the state space model. Using these parameters, the transient DC voltage and current variation of the PSCAD model were validated by comparing them to the values acquired from a real HVDC system, particularly under AC line-to-ground fault conditions in [21]. The PSCAD model has been further developed for application of the proposed control method in this paper.…”

“…The higher-order terms in (4) and (5) can be removed using the additional equations, expressed in matrix form: (21) …”

“…Additionally, simulation case studies are carried out using MATLAB, with the state space model of the Jeju-Haenam HVDC system implemented as a test case and compared to its comprehensive PSCAD model. In the author's previous paper [21], the PSCAD model was developed using real HVDC system parameters and verified through comparison with actual operating data on transient DC voltage and current variations. The main contributions of this paper are summarized below: • A new control method for an LCC HVDC system is proposed to improve the short-term operating margin of DC power transfer and the transient response by directly regulating both the DC voltage and current.…”