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Transmitting power using high-voltage direct current (HVDC) systems instead of high-voltage alternating current (HVAC) ones becomes desirable for integrating remote wind farms. Nowadays, Egypt planned to increase the wind power generation in the Red Sea zone from 1400 to 4000 MW by 2022. Unfortunately, the full capacity of the existing 220 kV HVAC...
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The imminent advent of large-scale green hydrogen (H2) production raises the central question of which of the two options, transporting "green" molecules, or transporting "green" electrons, is the most cost-effective one. This paper proposes a first-of-its-kind mathematical framework for the optimal integrated planning of electricity and H2 infrast...
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... Additionally, RESs with bulk capacity are continually being integrated into the grid in response to environmental concerns raised by fossil fuel-based generation [2]. Because of the dynamic fault current characteristics of large-scale WFs, integrating them at the transmission level results in a less-responsive transmission grid protection mechanism [3][4][5][6][7]. Many in-system security measures become ineffective when the WF's power output alters dramatically, particularly when the WF output is low [7,8]. ...
Transmission line conventional current differential schemes are significantly impacted by the dynamic fault current features, transient behavior, and unpredictable power generation of large-scale doubly fed induction generator-based wind farms (DFIG-WFs). Further, combined effects of WFs and flexible alternating current transmission system (FACTS) controller have adverse effect on various unit protection schemes. Normal transmission lines have a current differential between the two ends that rises with line length. If the WFs power output is low, the capacitive charging current may match the load current. Conventional differential protection methods are facing difficulties in the presence of WFs. This research proposes a data-driven approach to determine the effects of several scenarios with significant offshore WFs coupled to transmission lines on differential relay characteristics. The per-phase differential current is calculated using the short-term matrix pencil method (STMPM) based signal reconstruction technique. The net change in the current magnitude is then determined by estimating the first- and second-order derivatives of this data. Lastly, a disturbance detection index (DDI) is derived from the Euclidean distance between these first and second derivative components. The PSCAD/EMTDC simulation studies that were carried out show that the suggested strategy functions satisfactorily for a variety of disturbances, such as internal and external faults, fault resistance, fluctuating fault position, WF penetration changes, and other types of non-fault switching events.
... Compared to high voltage AC (HVAC) systems, high voltage DC (HVDC) systems are more economically and technically effective, making them the preferred option for connecting renewable energy sources [1,2]. Line commutated converter based high voltage DC (LCC-HVDC) is widely used in longdistance transmission and asynchronous grid interconnection due to its advantages of large transmission capacity, low system loss and good operation stability [3,4]. ...
... Consider the sampling frequency is not too high, and the line for more than 10 kHz signal attenuation is serious, to meet the bus wave impedance can be approximated as 0 frequency conditions, the 10 kHz transient signal is used for fault analysis. This paper specifies that both ends of the current direction to the bus pointing line for the positive direction, at this time the end N transient current is (2) ...
Affected by inverter station commutation failure and fast control, line fault characteristics are obviously different from traditional AC transmission line fault characteristics. The existing protection methods for AC line connected to line commutated converter based high voltage DC (LCC‐HVDC) inverter station (ACLs) have the problems of complex setting, weak anti‐noise and high demand for data synchronization. This paper proposes a pilot protection scheme based on high‐frequency transient current waveform similarity. Firstly, with analyzing the fault traveling wave propagation process, the obvious differences are found in the transient current waveforms at both ends of the line when internal and external faults occur. Then the similarity of transient current waveforms is measured with the improved longest common similar subsequence (LCSS) method. And the weak high‐frequency current is extracted with the improved synchronous squeezed S‐transform (SST) method. Finally, a large number of power systems computer aided design (PSCAD) simulation results show that the proposed protection method does not require strict data synchronization, has strong anti‐noise performance, and is tolerant to the influence of abnormal point fluctuations.
... In order to give full play to the role of relay protection, advanced equipment, perfect systems, and qualifed staf are essential parts. Power enterprises should be fexible in actual operation [26][27][28][29][30]. ...
In order to estimate the power system accurately and identify anomaly detection in real time, an identification method of anomaly detection in power system state estimation based on Fuzzy C-means algorithm is proposed. Considering the problems of scale and redundancy of power system measurement data, effective measurement data of the power system is extracted by the principal component analysis method. On this basis, the power system state estimation model established by particle swarm optimization support vector machines is used to judge the operational state of the power system. An anomaly detection identification method based on fuzzy C-means algorithm is proposed to cluster the measured data and identify the anomaly detection of power system. The experimental results show that this method can accurately estimate the state of the power system and has the highest identification accuracy for anomaly detection compared with similar methods. When the equivalent measurement data is affected by noise, the identification delay of this method for anomaly detection in a power system is 1 s, and the real-time performance is high.
In recent years, MMC-HVDC technology has attracted attention from all countries because of its many advantages in power controllability and transmission scalability and achieved rapid development. Therefore, this article takes the MMC-HVDC system as the research object and explores its control and protection system. This article analyzes two major control algorithms for MMC, and a control model of MMC under unbalanced AC voltage is designed, and an improved NLC control strategy is proposed. Finally, by building a system simulation platform, the advantages of the traditional algorithm and the control algorithm proposed in this paper are compared, to verify its effectiveness. The data shows that under the traditional control strategy, the amplitude of the fundamental current on the load side is 9.4 A, and the THD is 8.36%. Fourier decomposition of the circulating current contains 2.21 A of the second harmonic component, accounting for 45.28%; the improved type is used. Under the NLC modulation strategy, the amplitude of the fundamental current on the load side is 9.7 A, and the THD is 3.12%. Fourier decomposition obtains the second harmonic component of 1.12 A in the circulating current, and the second harmonic component accounts for 29.48%. It can be seen that this control strategy can improve the control performance of other indicators such as current and voltage.
