Remote Backup Research Articles

A Higher Performance Data Backup Scheme Based on Multi-Factor Authentication.

Remote data backup technology avoids the risk of data loss and tampering, and has higher security compared to local data backup solutions. However, the data transmission channel for remote data backup is not secure, and the backup server cannot be fully trusted, so users usually encrypt the data before uploading it to the remote server. As a result, how to protect this encryption key is crucial. We design a User-Centric Design (UCD) data backup scheme based on multi-factor authentication to protect this encryption key. Our scheme utilizes a secret sharing scheme to divide the encryption key into three parts, which are stored in the laptop, the smart card, and the server. The encryption key can be easily reconstructed from any two parts with user's private information password, identity and biometrics. As long as the biometrics has enough entropy, our scheme can resist replay attacks, impersonation user attacks, impersonation server attacks, malicious servers and offline password guessing attacks.

The adaptability research and evaluation of digital distance protection based on Python and PSCAD

With the development of power systems, digital distance protection, as an innovative and cutting-edge technology, plays a crucial role in ensuring the stable operation of the power grid. Due to its high precision, rapidity, and reliability, digital distance protection has become a key component of power system safety. Distance protection is widely used in distribution networks at or below 35 kV. Therefore, studying its adaptability and effectiveness as a remote backup protection can provide an effective foundation for improving grid security.With the utilization of Python and PSCAD, the adaptability of digital distance protection is meticulously examined in the context of low voltage side faults in 110 kV/35 kV transformers, specifically as a remote backup protection measure. The core objective of this investigation is to assess the efficacy of this protection strategy in upholding the safety and reliability of power systems. To achieve this, 3 approaches is employed: theoretical analysis, simulation modeling, and experimental validation. This process allows for a comprehensive evaluation of the performance characteristics and application efficacy of digital distance protection. The insights garnered from this meticulous study offer profound understanding into the strengths and potential limitations of this protection paradigm, serving as a solid foundation for the refinement of existing protection strategies and the enhancement of the overall resilience of power systems. In essence, this article aims to evaluate the effectiveness of digital distance protection as a remote backup protection strategy for faults on the low-voltage side of 110 kV/35 kV transformers. The core objective is to assess the efficacy of this protection strategy in maintaining the safety and reliability of the power system.

Optimal Scheme of Remote Backup Automatic Switch Applied to Renewable Energy Grids

The support of renewable energy to the bus voltage during the grid fault period will cause the failure action of the backup automatic switch (BPAS). Moreover, the improper coordination of renewable energy and source supply lines in the process of BPAS operation will lead to the asynchronous close of a circuit breaker, which seriously threatens the stable operation of the power system. To solve the above problems, an optimal operation strategy applied to the remote BPAS is proposed in this paper. Firstly, the operation logic and characteristics of internal BPAS and remote BPAS are analyzed. Secondly, the mechanism of failure action and asynchronous close of a circuit breaker in regional power grids with renewable energy sources are analyzed. Then, to improve the speed and reliability of the BPAS, a strategy of remote BPAS operation suitable is proposed. To avoid the problem of failure action, by monitoring the low-frequency condition of the regional power grid, the strategy accelerates the bus voltage loss to shorten the operation time of the BPAS. Moreover, the operation conditions of BPAS are optimized to avoid the asynchronous close of the circuit breaker between renewable energy and source supply lines. Finally, the experimental results in the 110 kV transformer substation verify that the improved remote BPAS strategy can effectively improve the reliability and quickness of the grid connecting to renewable energy.

Sistem Koordinasi Rele Jarak Untuk Pengaman Utama Dengan Rele Arus Lebih Pada Saluran Udara Tegangan Tinggi Di Wilayah Buduran

The transmission system plays an important role in maintaining the continuity of the distribution of electrical energy from one region to another. Disturbances in transmission lines are caused by short circuits, overloads, lightning surges, natural disturbances and others. For this reason, a protection system is needed that is reliable and can identify disturbances quickly while protecting the disturbed part of the system from other parts that can still operate normally. However, the protection system can experience operational failure due to various factors, therefore, apart from the main protection, backup protection is needed which can work when the main protection fails to work. Distance relays can be used as primary protection as well as remote backup protection on high voltage overhead lines. Meanwhile, the overcurrent relay is used as local backup protection if the distance relay fails to work. In this paper, a protection system is designed for the Buduran Main Substation channel using a combination of distance relays as main protection and overcurrent relays as backup protection using simulation method the Digsilent Power Factory. The overcurrent relay will trip at 0.5 and 0.15 seconds. From the Load Flow results, the value is obtained = 3,615 kA, = 4,67 kA and The range impedance according to the conductor cable data at the Buduran region 0,9676, Zone1 1 0,79Ω; 80%, Zone2 1,19Ω; 120% dan Zone3 as 1,48Ω is 150%. Thus the research can be declared successful in carrying out overcurrent protection

RAM 디스크 원격 백업을 통한 장애 복구 방법

RAM 디스크는 디스크 입출력 성능이 높지만, 휘발성 저장 매체이므로 전원 공급 단절에 따른 데이터 소실문제가 있다. 본 논문에서는 RAM 디스크의 데이터 소실 문제를 해결하기 위해 전체 파일 시스템을 원격 시스템에 백업하는 방법을 제안한다. 본 논문에서 제안하는 방법은 디스크 읽기, 쓰기 요구를 처리하는 RAM 디스크 장치 구동기가 쓰기 요구를 처리하는 중에 대상 디스크 블록을 원격 시스템에 전송하여 저장한다. 또, 본 논문의 장애 복구 방법은 RAM 디스크 드라이브 사용을 위해 드라이버가 적재될 때 원격 시스템으로부터 전체 파일 시스템을 복구하여 사용한다. 따라서, 본 논문에서 제안한 방법의 RAM 디스크는 하드웨어 고장 또는 조직 업무 이관 등 호스트 교체가 필요한 경우에 새로운 하드웨어 환경에서 파일 시스템을 효과적으로 복구할 수 있다. 본 논문에서 제안한 장애 복구 방법이 유효함을 보이기 위해 시험 구현을 하였으며, RAM 디스크의 파일 시스템이 정상적으로 복구됨을 확인하였다.

Optimization of Impedance-Accelerated Inverse-Time Over-Current Protection Based on Improved Quantum Genetic Algorithm

This paper proposes an impedance-accelerated inverse-time over-current protection optimization scheme based on the improved quantum genetic algorithm. First, the speed of remote backup protection is improved by increasing the optimization level of backup protection. Second, to ensure the coordination of protection when the distributed generation is connected to the distribution network, a mathematical model for the optimization of inverse time protection parameters is established. The mathematical model takes the minimum total action time of the optimized main and backup protection as the objective function, and the selectivity and sensitivity requirements of the protection as the constraints. In addition, the genetic algorithm is improved from four aspects: coding method, population initialization, quantum revolving gate, and variational evolution. The theoretical analysis and simulation results show that the proposed scheme can effectively improve the selectivity and operation speed of the protection.

A travelling wave based primary and backup protection for MMC-MTDC transmission system using morphological un-decimated wavelet scheme

The primary protection speed requirement for the HVDC grid is much faster as compared to the conventional HVAC grid. This research article proposes a travelling wave-based primary and backup protection scheme for the multi terminal HVDC transmission system using the morphological un-decimated wavelet decomposition signal processing technique. Depending on the polarity and arrival time information of the first incident travelling wave at both DC transmission line terminals, the fault is identified to be either in the internal zone, forward external zone, or backward external zone of the DC transmission line. Each DC transmission line is covered by its own internal zone as well as forward & backward external zone of its neighbouring line. The internal zone fault identification of the protection scheme sends the primary relay trip signals to associated hybrid DC circuit breakers. But if the primary protection relay fails, then the neighbouring DC substation protection system identifies the fault either in forward external or backward external zone. Then it sends a remote backup trip signal to the DC circuit breaker in the forward or backward external direction with a coordinated time delay.

Centralized Multiple Back-Up Protection Scheme with Sharing Data between Adjacent Substations Based on IEC 61850

A centralized multiple back-up protection scheme with sharing data between adjacent substations based on IEC 61850 is suggested in this paper to overcome the inherent defects of a conventional back-up protection scheme such as uncertainty of a remote end condition, especially for a distance relay, long operating time delay, and IED/CT fails. A current differential protection element, a distance-based directional protection element, local back-up, and remote back-up protection elements are applied for the multiple back-up protection scheme suggested in this paper. The phasor voltage/current data of the IMU are transferred to a CPCU. In this paper, the IMU has two functions, which are local protection IED and merging unit, as well. The CPCU performs the back-up protection functions by using the phasor voltage/current data collected from other CPCUs located at the adjacent substations. IMU/CT fails are also considered. To verify the back-up protection scheme proposed, a testbed was composed of IMUs (implemented with ADS8688 and TMDSIDK572X), grand-master-clocks (LANTIME M1000-IMS), network switches (Syn 1588 Gbit switch), RTDS, and CPCUs. A target power system was modelled with RSCAD. The results of this research can be expected to provide a practical guide to constructing the future centralized protection for a digital substation.

Improved Deep Neural Network (IDNN) with SMO Algorithm for Enhancement of Third Zone Distance Relay under Power Swing Condition

A zone 3 distance relay is utilized to provide remote backup protection in the event that the primary protection fails. However, under stressful situations such as severe loads, voltage, and transient instability, the danger of malfunction in distance relay is relatively high since it collapses the system’s stability and reliability. During maloperation, the relay does not function properly to operate the transmission line. To overcome this problem, an advanced power swing blocking scheme has been developed. An improved DNN-based power swing blocking system is proposed to avoid the maloperation of the distance relay and improve the system’s reliability. The current and voltage signal of the system is sensed, and the sensed data is fed into the Improved Discrete Wavelet Transform (IMDWT). The IMDWT generates the coefficient value of the sensed data and further computes the standard deviation (SD) from the coefficient, which is used to detect the condition of a system, such as normal or stressed. The SD value is given to the most valuable algorithm for the improved Deep Neural Network (IDNN). In the proposed work, the improved DNN operates in two modes, the first mode is RDL-1 (normal condition), and the second mode is RDL-2 (power swing condition). The performance of the IDNN is enhanced by using the threshold-based blocking approach. Based on the threshold value, the proposed method detects an appropriate condition of the system. The proposed method is implemented in the Western System Coordinating Council (WSCC) IEEE 9 bus system, and the results are validated in MATLAB/Simulink software. The overall accuracy of the proposed method is 97%. The proposed method provides rapid operation and detects the power swing condition to trip the distance relay.

Innovative Adaptive Protection Approach to Maximize the Security and Performance of Phase/Earth Overcurrent Relay for Microgrid Considering Earth Fault Scenarios.

Microgrids are increasingly paying attention to the emerging of distributed energy resources. However, microgrid protection has challenged engineers because of the varying nature of fault current distribution during grid-connected and islanded operations. This paper suggests a novel approach of coordination between phase and earth fault overcurrent relays to ensure stability and security for the performance of protection schemes in active distribution networks. In this study, a combination of phase and earth overcurrent relays is coordinated to avoid mis-coordination in the overcurrent protection schemes. In the proposed approach, phase overcurrent function was employed as backup protection for earth fault function locally in the same relay instead of the traditional remote backup earth fault protection coordination approach. The suggested coordination approach provides a fast and reliable protection performance in different earth faults scenarios. The coordination was tested on the IEC Microgrid Benchmark network. Also, the objective function was modified to reduce the overall operational time using two recently developed metaheuristic optimization algorithms known as the charged system search (CSS) and Teaching-Learning-Based Optimization Algorithm (TLBO) in the MATLAB package. Finally, the time multipler setting values were adapted and compared to verify the speed and reliability of the proposed coordination approach using ETAP.

A failure detection method of remote disaster recovery and backup system

Failure detection is one of the basic functions of building a reliable disaster recovery backup system. Aiming at the application-level disaster recovery backup failure detection problem, this paper analyzes the remote disaster recovery center architecture and failure detection hierarchy, and predicts the arrival time of cross-domain heartbeat information through the back propagation neural network based on particle swarm optimization (PSO-BP). When the actual timeout is reached, the active Auxiliary Detection (AD) is used to improve the correctness of failure detection, and finally the effectiveness of method PSO-BP-AD is verified through simulation.

Fault zone identification and phase selection for microgrids using decision trees ensemble

Microgrid protection is one of the main challenges that hinders the growth in the number and variety of microgrids being developed. Fault zone identification and phase selection are among protection challenges that existing protection schemes fail to address. This paper proposes a voltage-restrained classifier-based relaying scheme to address the two protection selectivity problems. While fault detection is achieved via an undervoltage function to ensure the sensitivity of the proposed method, Decision Trees (DTs) ensemble functions are used for fault zone identification and phase selection to guarantee the selectivity of the protection scheme. The proposed approach can identify three zones, forward internal, forward external, and reverse external, which (i) facilitates the operation of a relay in primary and remote backup modes, and (ii) avoids nuisance operation under reverse faults, i.e., works as a directional element. The proposed phase selection function can identify all ten types of faults, which enables the isolation of the faulted phase(s) only. The proposed relaying logic does not require any form of communication, instead it relies on readily available sequence component measurements. Transient studies in PSCAD/EMTDC verify the performance of the proposed scheme under various faults and different microgrid operation modes.

Dependable Data Outsourcing Scheme Based on Cloud-of-Clouds Approach with Fast Recovery

Cloud computing is increasingly popular today. Cloud services such as data-outsourcing services provide a growing number of users access to cloud storage for large quantities of data, and enterprises are turning to cloud storage for cost-effective remote backup. In 2011, DEPSKY shows and overcomes four limitations hinder the effectiveness of cloud storage: loss of availability, loss and corruption of data, loss of privacy, and vendor lock-in. Unfortunately, DEPSKY lacks an error detection mechanism and comes with heavy computing costs. Therefore, we propose a new data-outsourcing scheme overcoming not only the four limitations, but also the shortcomings of DEPSKY. In this paper, we modify Nyberg's accumulator and apply it to our three proposed error-detection methods. Moreover, we specially design a fast recovery method that is faster than DEPSKY and alternative methods.

Summary of requirements for the use of cells and batteries in potentially explosive atmospheres

The use of wireless equipment in the industrial field is a modern trend both in terms of communication equipment, monitoring of gas concentration, environment or installations but also for remote controls and power backup. The energy source for such equipment are cells and batteries. The first part of the article addresses the risk of explosion and the peculiarities of flammable atmospheres. The second part was dedicated to the presentation of the types of cells suitable for use in explosive atmospheres. The last part presents a summary of the specific requirements of cells and batteries regarding the explosion protection.

Compensation voltage moduli comparison‐based wide‐area protection algorithm independent of data synchronism and integrity

Secondary direct-current loss within a substation is a severe event. In China, each line protection device is generally powered by one set of secondary direct current (DC) power system within a substation of 110 kV voltage level. In this case, the line protection devices will be immediately taken out of service when the secondary DC is lost, and the lines protected by them will lose their corresponding protections. Once a fault occurs on the line, only the remote back-up protection can be relied on to isolate the fault, which expands the fault influence and increases its clearance time. To handle the above problem, a novel wide-area protection algorithm based on compensation voltage moduli comparison is proposed, which is independent of multi-terminal data synchronism. Then, a comprehensive protection strategy composed of the proposed protection algorithm and the original local distances protection is proposed. The results from a power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC)-based simulation verify that the proposed protection algorithm has higher sensitivity. The comprehensive protection strategy could cope with most line faults effectively, even if only partial data are available, the selectivity and speed of which are better than that of distance protections.

ECC-CRT: An Elliptical Curve Cryptographic Encryption and Chinese Remainder Theorem based Deduplication in Cloud

Cloud computing provides the data storage facility for the maintenance, management and remote backup of the data. The storage cost and data retrieving time has increased. To encrypt, the Elliptical Curve Cryptographic and to generate key the Chinese Remainder Theorem (ECC-CRT) based deduplication scheme is proposed. Data deduplication is the process of eliminating the repeated data in cloud storage. Cloud service provider receives the encrypted data and checks for duplication. Deduplication is performed by using cosine similarity checking. The advantage of the method is, it avoids malicious upload and downloads in storage space. The performance is compared with existing methods.

Protection of Inverter-Based Islanded Microgrids via Synthetic Harmonic Current Pattern Injection

Faults in inverter-based islanded microgrids can be a formidable protection challenge due to the limited fault current contribution of inverters. This paper designs a selective and sensitive protection scheme by injecting a pattern of up to three synthetic harmonics utilizing the flexibility of existing inverter-based distributed generation (IBDG) controllers (called injection pattern [IP]). The measured pattern (MP) by each relay is the result of the combination of IPs from IBDGs at different locations in a microgrid. To ensure that relays measure different MPs for forward and reverse faults, an optimization model is formulated to set and minimize the total number of IPs by IBDGs. A pattern-based directional element is proposed based on the cosine similarity measure between the MP and the predefined characteristic pattern (CP) of each relay. CPs are set offline as the normalized MPs of forward faults. Moreover, a new direction-comparison relaying scheme is devised, which comprises of permissive overreaching transfer trip (POTT) and direction zone-interlocking (DZI) for primary and remote backup protection, respectively. Transient studies in PSCAD/EMTDC verify the performance of the proposed scheme under various faults and different microgrid topologies.

Individual and Collective Recognition Capability of the Measuring Elements of Relay Protection

The existing method is to estimate the recognition capability of relay protection on the plane of fault parameters of a power facility simulation model is described. Adevelopment and generalization of this approach is to transfer the estimation procedure to the multidimensional domain of modes controlled by relay protection (a-modes). The task is to select the part of the domain where one or several measuring elements are capable of discriminating a-modes from alternative â-modes in which the action of relay protection is prohibited. Failure to recognize an a-mode can be attributed to its physical indistinguishability from some â-mode (absolute unrecognizability) or the incapability of the measuring elements to ensure sufficient recognition capability (relative unrecognizability). The recognition capability of the measuring elements of remote backup protection in the situation where the a-mode is a three-phase short circuit in a branch, and the â-modes are the connection of the line to the grid is evaluated as an example.

Development of a Low Cost and Path-free Autonomous Patrol System Based on Stereo Vision System and Checking Flags

Nowadays, security guard patrol services are becoming roboticized. However, high construction prices and complex systems make patrol robots difficult to be popularized. In this research, a simplified autonomous patrolling robot is proposed, which is fabricated by upgrading a wheeling household robot with stereo vision system (SVS), radio frequency identification (RFID) module, and laptop. The robot has four functions: independent patrolling without path planning, checking, intruder detection, and wireless backup. At first, depth information of the environment is analyzed through SVS to find a passable path for independent patrolling. Moreover, the checkpoints made with RFID tag and color pattern are placed in appropriate positions within a guard area. While a color pattern is detected by the SVS, the patrolling robot is guided to approach the pattern and check its RFID tag. For more, the human identification function of SVS is used to detect an intruder. While a skeleton information of the human is analyzed by SVS, the intruder detection function is triggered, then the robot follows the intruder and record the images of the intruder. The recorded images are transmitted to a server through Wi-Fi to realize the remote backup, and users can query the recorded images from the network. Finally, an experiment is made to test the functions of the autonomous patrolling robot successfully.

Protection of High-Voltage DC Grids Using Traveling-Wave Frequency Characteristics

Fast dc fault detection in high-voltage dc (HVdc) grids is paramount due to the possibility of attaining a severely high fault current within few milliseconds. This article proposes a new traveling-wave (TW) based protection scheme to detect and locate faults in HVdc grids. In contrast to the existing TW-based protection and fault location approaches, the proposed scheme, first, utilizes only the first locally measured TW after the inception of a fault, and, second, focuses on the frequency content and polarity of the TW, rather than its arrival time. The direction of the TW is identified based on the pattern of the current TW waveform. A frequency spectral ratio of the current TW is proposed to identify the fault zone and fault location with high accuracy. The proposed method ensures a detection speed of 50 $\mu$ s on overhead lines and 500 $\mu$ s on underground cables. A remote backup scheme is coordinated with the primary protection and operates within 1.05 ms, which meets the speed requirement of HVdc grids. The performance of the proposed scheme has been, first, assessed using the CIGRE B4 HVdc test grid under various conditions, and, second, compared to existing single- and two-terminal TW methods.