Search

Event location in power systems is quite essential information for system operators to enhance control-room situational awareness capability. Therefore, it is of great importance to develop an event location estimation algorithm for transmission systems with high accuracy. With the development of wide-area measurement system (WAMS) such as FNET/GridEye, and the synchrophasor measurement devices (SMDs) such as frequency disturbance recorders (FDRs), the synchronous measurement data including frequency, voltage amplitude and phase angle can be collected and used for event location estimation. First, the phase angle and rate of change of frequency (RoCoF) trajectories are respectively used for determining two sets of wave arrival time associated with each FDR. Then, a convolutional neural network (CNN) is utilized to determine the wave arrival order to select the more suitable set of wave arrival times for a given case and to perform corresponding modifications. Next, the oscillation intensity associated with each FDR is determined based on phase angle trajectories in the center of inertia (COI) coordinate system. Finally, the multiple criteria for event location estimation are represented. Case studies and comparisons between the proposed and previous algorithms using actual and confirmed cases in U.S. power systems are performed to demonstrate the effectiveness and improvement of the proposed algorithm in practical applications. [ABSTRACT FROM AUTHOR]

Programmable logic controllers (PLCs) are used to control devices throughout the power system since they have fast control capabilities and can utilize multiple types of communication interfaces. Therefore, studying and mitigating their vulnerabilities to electromagnetic pulse is important for the reliability of PLC operations. In this article, an effective impedance measurement scheme is proposed and demonstrated for three PLCs to estimate their susceptibility to an electromagnetic pulse. The equivalent nonuniform transmission line model is established to eliminate the impact of the fixture in the de-embedding process. Then, different parameters of the impedance measurement setup are explored. Based on the measured impedance, the equivalent circuit is established to calculate the response of the device when subjected to the electromagnetic pulse. The voltage and current responses of different interfaces are compared utilizing the developed pulsed current injection (CI) method. Finally, the impedance measurement scheme is verified through testing using three measuring instruments. And the CI simulation experiments reveal the characteristics and susceptibilities of different PLCs interfaces, indicating that some protection measures are required for the reliable operation of the PLC. [ABSTRACT FROM AUTHOR]

This article introduces a new scheme for suburban renewable energies, hydrogen plant, and logistics (SRE-HP-LC) integration scheme and dispatching. The objective of the proposed SRE-HP-LC integration scheme aims at coordinating the operation of renewable energies, hydrogen production, and storage and logistic transportation. In order to take advantages of various energy conversion techniques to enhance the energy utilization rate and improves the financial revenue of the integration scheme, a completed dispatching and operating scheme for the proposed SRE-HP-LC integration scheme is introduced in the scheme stage. A multiple-demand response objective function is developed in the operation stage to coordinate the hydrogen energy usage in the SRE-HP-LC integration scheme. The proposed SRE-HP-LC integration scheme considers the uncertainties of renewable energy output and truck demand so that it improves the revenue of every component in the integration scheme. Case studies on a general integration system verify the effectiveness and economic value of the proposed SRE-HP-LC integration scheme. [ABSTRACT FROM AUTHOR]

The front-end circuit used in the pulsar acquisition of the radio telescope determines the availability of the entire pulsar-based timing framework. However, it would be expensive and resource consuming to use a real radio telescope in the circuit design process. To address this issue, in this article, the hardware-in-the-loop simulation solution is proposed to generate, sample, and extract pulse signals in real time. The artificial pulse generation method is first proposed to generate the pulses that are close to real pulsar signals. Then, three analog front-end circuit architectures (AFCAs) are proposed to generate the analog pulses, including the superposition, attenuator, and attenuator-based superposition structures. The generated pulses are close to the real pulsar signal in shape, amplitude, and noise level. Next, a pulsar-based timing synchronization framework that can be used to improve the timing accuracy of the wide-area monitoring systems is developed to process the sampled data. Multiple experiments are conducted to verify the effectiveness of the analog front-end and the pulsar-based timing synchronization framework using the simulated pulse and real pulsar signals. The results demonstrated that the designed AFCAs can generate effective analog pulses, and is convenient and flexible. [ABSTRACT FROM AUTHOR]

With the development of dc renewable power generation and dc power consumption, more and more attention has been paid to residential low-voltage dc (RLVDC) power systems in recent years because of their advantages in conversion efficiency and control flexibility. Meanwhile, there are still some obstacles and challenges in the practical application of RLVdc due to the lack of standardization. One of the most important issues in RLVdc standardization progress is the voltage level standard. In this article, a comparative study on the performance of different RLVdc system voltage levels is presented. The main purpose of the article is to provide a voltage level selection guidance for energy prosumers and equipment manufacturers interested in RLVdc systems. The voltage levels commonly used in academia and industry, from 220 to 750 V, are compared and analyzed considering their influence on compatibility, topology, power supply capability, and safety. The article contains a research surveys, market statistics, power system simulations, and calculations with simplified models. The results of the comparative study show that ±375 V is optimal for the RLVdc system in cases with large power ratings and voltage levels below 240 V are suitable for RLVdc systems with special safety requirements. [ABSTRACT FROM AUTHOR]

The high voltage direct current (HVdc) intertie has been applied to provide ancillary-services for ac grids, utilizing the real-time feedback from phasor measurement units (PMUs). However, PMU data communication is vulnerable to false data injection attacks (FDIA) due to protocol defects, thus the HVdc ancillary control and system stability will be threatened. To address this issue, this article proposes a novel HVdc control strategy based on a hybrid data-driven (HDD) methodology. The HDD methodology is first proposed to detect the types and duration time of multiple frequency attacks. Specifically, the Hilbert Huang transform (HHT) is used to decompose the frequency data, using variational mode decomposition instead of the traditional empirical mode decomposition, to extract data features. Second, a multikernel support vector machine is proposed to classify the attacked data based on the designed distinctive features from HHT. Meanwhile, the attacking duration time is decided using an unsupervised technique. Third, an HDD-based HVdc ancillary control strategy is established to eliminate the effect of FDIAs on the HVdc frequency response. Comprehensive experiments of HDD-based HVdc ancillary controls under different FDIAs suggest that the proposed HDD could fast and accurately classify the FDIAs, and the HDD-based HVdc ancillary control strategy could significantly suppress the impact of the FDIAs. [ABSTRACT FROM AUTHOR]

Due to the independent controllability and fast power regulation capability, the High Voltage Direct Current (HVDC) system could be a prospective technology to provide multiple ancillary services to the system besides conventional bulk power transmission. However, with the increase of False Data Injection Attacks (FDIAs) on PMU data, the HVDC system could have the wrong response once the collected data that the HVDC system relied on is attacked, thus threatening the system operating security. How to ensure the security of the PMU-based HVDC ancillary service control become an urgent issue. To mitigate the risk, this paper proposed an HVDC attack-defense control based on the FDIAs detection method. Firstly, the Squeeze-Excitation based Double Convolutional Neural Networks (SE-DCNN) is proposed to realize fast identification of the attacking frequency type based on the time and frequency domain signals. The duration time of FDIAs is detected by the local outlier factor. Then, utilizing the results from SE-DCNN, HVDC ancillary service control framework is reorganized and an HVDC attack defense control is proposed for suppressing the potential influence of various types of FDIAs on the HVDC system ancillary service. Different experiments results demonstrate that the proposed method has the ability to significantly mitigate the frequency deviation and oscillation under the FDIA. [ABSTRACT FROM AUTHOR]

Urban power grids are facing many operational and expansion challenges to meet further demand growth and increased reliability requirements. Advanced transmission technologies have been considered by the electric utilities to effectively increase the utilization of existing infrastructure and operational flexibility. The focus of this paper is on VSC-HVDC technologies for urban power grid enhancement and modernization. First, a potential technical scheme is proposed for converting an existing AC circuit to DC operation, which could boost the power transfer capability of the critical transmission corridor and increase network operational flexibility. Second, this paper proposes three operation modes for the VSC-HVDC interties in urban power grids corresponding to normal, emergency and island operating conditions, respectively. An integrated, adaptive emergency control strategy (AEC) is proposed that can enable adaptive power flow responses of the VSC-HVDC intertie under varying system operating conditions and critical contingencies. The flexibility and effectiveness of the proposed operational principles of urban VSC-HVDC intertie and the corresponding control strategies are verified in PSCAD/EMTDC using a realistic urban power grid in China. [ABSTRACT FROM AUTHOR]

The increasing deployment of phasor measurement units and the advances of their reporting rates are challenging the present data centers in terms of storing and analyzing large-volume data. Under power system disturbance conditions, it is difficult to retain critical information while compressing the synchrophasor data effectively. This article combines the cross entropy and the singular value decomposition, proposing a novel model to compress the synchrophasor data to an extremely small size yet keep superior accuracy. The proposed model is extensively tested and compared with the state-of-the-art algorithms using the simulated and the FNET/GridEye field-collected data. The result indicates that the proposed algorithm has superior performance in compressing the data while retaining critical information under disturbance conditions. [ABSTRACT FROM AUTHOR]