scholarly journals Online Parameter Estimation for Fault Identification in Multi-Terminal DC Distribution Grids

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5630
Author(s):  
Ting Wang ◽  
Liliuyuan Liang ◽  
Xinrang Feng ◽  
Ferdinanda Ponci ◽  
Antonello Monti
Keyword(s):  
Fault Location ◽  
Short Circuit ◽  
Fault Identification ◽  
Generic Model ◽  
Distribution Grid ◽  
Accurate Identification ◽  
Power Sources ◽  
Dc Distribution ◽  
Time Simulation ◽  
Distribution Grids

Fast and accurate identification of short-circuit faults is important for post-fault service restoration and maintenance in DC distribution grids. Yet multiple power sources and complex system topologies complicate the fault identification in multi-terminal DC distribution grids. To address this challenge, this paper introduces an approach that achieves fast online identification of both the location and the severity of faults in multi-terminal DC distribution grids. First, a generic model describing the dynamic response of DC lines to both pole-to-ground and pole-to-pole faults with fault currents injected from both line ends is developed. On this basis, a Kalman filter is adopted to estimate both the fault location and resistance. In the real-time simulation of various fault scenarios in a three-terminal DC distribution grid model with Opal-RT platform, the proposed method is proved to be effective with a short response time of less than 1 ms.

scholarly journals A Two-Step State Estimation Algorithm for Hybrid AC-DC Distribution Grids

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1967
Author(s):  
Gaurav Kumar Roy ◽  
Marco Pau ◽  
Ferdinanda Ponci ◽  
Antonello Monti
Keyword(s):  
State Estimation ◽  
Distribution System ◽  
Renewable Energy Sources ◽  
Estimation Algorithm ◽  
The State ◽  
Second Step ◽  
Distribution Grid ◽  
Dc Distribution ◽  
Attractive Option ◽  
Distribution Grids

Direct Current (DC) grids are considered an attractive option for integrating high shares of renewable energy sources in the electrical distribution grid. Hence, in the future, Alternating Current (AC) and DC systems could be interconnected to form hybrid AC-DC distribution grids. This paper presents a two-step state estimation formulation for the monitoring of hybrid AC-DC grids. In the first step, state estimation is executed independently for the AC and DC areas of the distribution system. The second step refines the estimation results by exchanging boundary quantities at the AC-DC converters. To this purpose, the modulation index and phase angle control of the AC-DC converters are integrated into the second step of the proposed state estimation formulation. This allows providing additional inputs to the state estimation algorithm, which eventually leads to improve the accuracy of the state estimation results. Simulations on a sample AC-DC distribution grid are performed to highlight the benefits resulting from the integration of these converter control parameters for the estimation of both the AC and DC grid quantities.

scholarly journals Fault-Ride-Through Approach for Grid-Tied Smart Transformers without Local Energy Storage

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5622
Author(s):  
Justino Rodrigues ◽  
Carlos Moreira ◽  
João Peças Lopes
Keyword(s):  
Energy Storage ◽  
Renewable Energy Sources ◽  
Computational Simulation ◽  
Low Frequency ◽  
Voltage Sags ◽  
Distribution Grid ◽  
Power Electronic Converters ◽  
Dc Distribution ◽  
Fault Ride Through ◽  
Distribution Grids

The Smart Transformer (ST) is being envisioned as the possible backbone of future distribution grids given the enhanced controllability it provides. Moreover, the ST offers DC-link connectivity, making it an attractive solution for the deployment of hybrid AC/DC distribution grids which offer important advantages for the deployment of Renewable Energy Sources, Energy Storage Systems (ESSs) and Electric Vehicles. However, compared to traditional low-frequency magnetic transformers, the ST is inherently more vulnerable to fault disturbances which may force the ST to disconnect in order to protect its power electronic converters, posing important challenges to the hybrid AC/DC grid connected to it. This paper proposes a Fault-Ride-Through (FRT) strategy suited for grid-tied ST with no locally available ESS, which exploits a dump-load and the sensitivity of the hybrid AC/DC distribution grid’s power to voltage and frequency to provide enhanced control to the ST in order to handle AC-side voltage sags. The proposed FRT strategy can exploit all the hybrid AC/DC distribution grid (including the MV DC sub-network) and existing controllable DER resources, providing FRT against balanced and unbalanced faults in the upstream AC grid. The proposed strategy is demonstrated in this paper through computational simulation.

scholarly journals Fault Location Method for DC Distribution Systems Based on Parameter Identification

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1983 ◽  
Author(s):  
Yan Xu ◽  
Jingyan Liu ◽  
Weijia Jin ◽  
Yuan Fu ◽  
Hui Yang
Keyword(s):  
Parameter Identification ◽  
Distribution System ◽  
Distribution Systems ◽  
Fault Location ◽  
Fitness Function ◽  
Short Circuit ◽  
Location Method ◽  
Dc Distribution ◽  
Transition Resistance ◽  
Short Circuit Fault

When a short circuit fault occurs on the DC side line, the fault current reaches the peak within a few milliseconds, and the voltage drops significantly. This phenomenon can cause overcurrent flowing through the DC line, semiconductor devices, and AC side, which is a major threat to the operation of the entire system. To solve this problem, this paper proposes a fault location scheme based on parameter identification. Firstly, the entire DC distribution system is regarded as a graph. The intersections of the distribution system lines are regarded as vertices. The current flow of each line is regarded as a directed edge. The network topology matrix is constructed and a fault type recognition algorithm is proposed based on graph theory. Secondly, the mathematical model of the pole-to-pole short-circuit fault and pole-to-ground short-circuit fault are analyzed with double-ended electrical quantities. Transform the fault location problem into a parameter identification problem, four parameters to be identified are extracted, and the fitness function is constructed separately for two kinds of fault cases. Thirdly, a genetic algorithm (GA) is adopted to identify the value of parameters. Considering the fault types, transition resistance and fault location, the Matlab/Simulink simulation platform is used to simulate 18 fault conditions. The simulation results show that the positioning error of the fault location method is less than 1%, which is not affected by the transition resistance and has strong robustness.

Short-Circuit Fault Location Interval Recognition Criteria in Electrical System

2019 ◽  
Vol 11 ◽  
pp. 33-39
Author(s):  
Yury Ya. LYAMETS ◽  
◽  
Mikhail V. MARTYNOV ◽  
Alexander N. MASLOV ◽  
◽  
...  
Keyword(s):  
Fault Location ◽  
Short Circuit ◽  
Electrical System ◽  
Short Circuit Fault
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