Remote Backup Protection Research Articles

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.

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

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.

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.

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.

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.

Special protection system to cope with the unavailability of sampling values from an entire substation

A special protection system is proposed to respond to a challenge such as that a substation must be immediately taken out of service or only be protected by a remote backup protection without selectivity if the sampling system of this substation breaks down or the samplings are unavailable even though the GOOSE channel is functioning normally. After the special protection system perceives an abnormality of the sampling system of the substation, it first locates the rough fault region using a wide area measurement system based current differential protection scheme of the sound side of the lines connected to the substation with an abnormal sampling system. Then, a novel compensation voltage difference scheme is proposed to determine the faulty line within the recognized rough fault region. Combined with the zone I distance protection scheme, a comprehensive special protection scheme to address a serious sampling abnormality is proposed. Theoretical analysis and PSCAD and MATLAB based simulation studies show that the proposed scheme has the advantages of high reliability, sensitivity and capability of withstanding a fault resistance.

Study of Coordination on Protection Relay in High Voltage Transmission 150 kV (Payakumbuh – Koto Padang, West Sumatra)

The disturbance of the high voltage transmission can be caused by a short circuit, overload, lightning surge, and other natural disturbances. That disturbance can lead to disruption of the distribution of electricity and damage to the electric power system installation equipment. A reliable protection system that can identify the disturbance quickly and also can securing affected parts of the system from other parts that can still operate normally are needed. Protection system operation may fail due to various factors; therefore, in addition to primary protection required backup protection that can work as primary protection fails to work. Distance relays can be used as primary protection as well as remote backup protection on high-voltage transmission. While overcurrent relay (OCR) and ground fault relay (GFR) is used as a local backup if distance relay failed to work. This research conducted a study of protection relays coordination for primary protection or backup protection on the high-voltage transmission that connects to Payakumbuh substation and Koto Panjang substation. Coordination is done by calculating the distance relay settings that use as primary protection as well as remote backup protection relay settings and calculating the overcurrent and ground fault relay that used as local backup protection. From the calculation, we get setting time to coordinate distance relay, overcurrent relay, and ground fault relay. Setting time was conducted to the first zone of the distance relay within 0 sec, and the second zone within 0.4 sec and third zone within 1.2 sec. For overcurrent relay and ground fault relay use time delay 1 second where the value is above the value that used in the second zone of distance relay. Distance relay can be coordinated with the auto-reclose relay to close the circuit breaker automatically sometime after a temporary disturbance. Setting that use to auto reclose relay is dead time 1 second and reclaim time 40 second. The coordination between the distance relay with auto-reclose relay can improve the quality of distribution of electrical energy.

A new coordinated backup protection scheme for distribution network containing distributed generation

This paper proposes a new backup protection scheme, named coordinated backup protection (CBP) scheme, for distribution networks containing distributed generation. The proposed protection scheme takes into account the issues faced by traditional backup protection, such as difficulty in setting parameters and complex cooperation, and considers the features of distribution networks, such as changeable power flow because of high penetration of distributed generation sources and insufficient measuring quantities. The CBP scheme includes two aspects: coordinated substation protection and regional master substation protection, who also work as nearby backup protection and remote backup protection respectively. The two protections support each other by local information coordination and regional information sharing, in order to improve the reliability of fault identification. The configuration principles and performances of the proposed backup protection scheme are addressed in the paper. Different fault conditions in the IEEE 14-node system have been used to illustrate and verify the feasibility of the CBP scheme.

A new PMU based power swing detector to prevent mal-operation of distance relay

In conventional transmission line protection, a distance relay is used to provide the primary as well as remote backup protection. The voltage and current phasors measurement needed by the distance relay for determining the impedance may be affected by the power disturbances such as power swing. Consequently, this power swing may cause mal-operation of Zone three distance relays which in turn may affect on the reliability of the whole protective scheme. To mitigate these effects and hence improve the relay reliability, this work proposes a new real-time power swing detector using phasor measurement units for blinding the distance relay only during this transient disturbance. However, this developed detector will not block relay when the power swing accompanied with faults. To validate the present work, the performance of developed enhanced distance relay is tested by signals generated by Simulink/MATLAB simulator under different conditions. The test results show that this proposed scheme provides good discrimination between the transient currents and the fault current which in turn it may contribute in enhancing the reliability of Distance relay.

A modular neuro-wavelet based non-unit protection scheme for zone identification and fault location in six-phase transmission line

To overcome the constraints on land availability, infrastructure and environmental problems, six-phase transmission lines have been proposed as a potential alternative to increase the power transfer capability of existing transmission lines without major modification in the existing structure of three-phase double-circuit system. The non-availability of a proper protection scheme due to large number of possible faults has been the prime reason behind the low popularity and acceptance of six-phase system. In this regard, the present work proposes a protection scheme for six-phase transmission line based on the hybridization of discrete wavelet transform and modular artificial neural network. The fault information (approximate coefficients) in the voltage and current signals is captured using discrete wavelet transform. The standard deviation of the coefficients of voltage and current signals in each phase is then computed and given as input to modular artificial neural network, which aims at identifying the faulty section/zone and estimate its location. Test results exhibit that the proposed scheme effectively discriminates the faulted section and estimates the fault location with maximum error of 0.675 %. It offers primary protection to the total line length and also provides remote backup protection for the adjacent reverse section of the line using data at relaying point only and thus avoids the need of a communication link.

A Transfer Trip Scheme to Supervise Zone 3 Operation

Zone 3 of distance relay provides remote backup protection for adjacent transmission lines using local information. At times, zone 3 is prone to maloperation under stressed system conditions, which may cause serious threat to grid security. Zone 3 decisions can be more accurate, if fault pickup information of the adjacent line relays is availed. In this paper, zone 2 pickup signals of adjacent line relays are unified using simple logic gates and the information is transferred to supervise remote backup protection; the zone 3. Proposed method is tested for WSCC nine-bus and two-area four machine systems under different conditions and found to be accurate.

Design and Application of Analysis Software for Relay Protection Action Based on PAS

This paper applies the theory of expert system to analysis for relay protection action based on PAS. And it also summarizes various rules according to the experience of operating personals and relay protection personals for several years. All these rules are suitable for 110kV and 66kV regional networks. This paper not only analyzes three-phase current protection, zero-sequence current protection, distance protection etc, but also discusses some special situations such as under voltage lockout over-current protection for transformer, remote backup protection etc.

Determination of the optimum routine and self‐checking test time intervals for power system protection considering remote back‐up protection system failure

In this study, routine and self-checking tests are performed as one of the methods to maximise the availability and adequate operation of power system protection. However, optimum routine test time intervals (ORTTI) and optimum self-checking test time intervals (OSTTI) should be determined exactly to anticipate maintenance cost of power system protection precisely. Back-up protection system failure has a vital role in determining precise ORTTI and OSTTI, whereas most of the previous studies have assumed that back-up protection system is perfectly reliable. Therefore in this study, an extended Markov model is proposed to determine the ORTTI and OSTTI by considering remote back-up protection system failure probability. It is worth noting that both self-checking and monitoring facilities that improve reliability of the protection system are considered in the proposed Markov model. Simulation results demonstrate that variations in reliability indices, ORTTI and OSTTI for power system protection are significant when remote back-up protection system is not fully reliable.

Research on Fault Diagnosis Model for Substation with Redundancy Protection Based on Petri Net

Due to layering distribution, double network and dual-disposition characteristics of 750kV substation, Petri net diagnosis model which based on redundant protection for substation is proposed. In this model, a redundant knowledge representation method is adopted from components to the local and the whole, then components redundant diagnosis-model is constructed on basis of it. The model can be decomposed into main and redundant subnet-model based on Petri net by using two sets of protective device information, and considered remote backup protection, which realize fault tolerance of dual-machine. Through information fusion of redundant diagnosis model of components, the local and the overall model is established. The results show that the model achieves high efficiency and reliability.

High-speed non-unit transmission line protection using single-phase measurements and an adaptive wavelet: zone detection and fault classification

This work describes a transmission line protection scheme with two protection functions: directional zone and fault classification. The proposed scheme requires no information from remote ends and uses current measurements of only one phase of the three-phase systems for determining the fault direction, the faulted line and the fault type. Information concerning the high-frequency components of transient current signals is extracted with discrete wavelet transform (DWT) by using an adaptive wavelet, which has been specifically designed for relaying purposes, as analysis filter. After that, Bayesian linear discriminant analysis is employed for data classification. The present work highlights that the adaptive wavelet used here presents advantages for transmission line protection rather than predefined mother wavelets. Results demonstrate that the proposed scheme effectively distinguishes the faulted zone, the fault direction and the fault type. Therefore it offers primary protection to total line length, remote backup protection for the next transmission line and also the possibility to implement single-pole tripping. Current signals of roughly 2 ms are analysed then the proposed methodology can be implemented in high-speed protection schemes for extra- and ultra-high voltage (EHV/UHV) networks.

Adaptive load blinder for distance protection

This paper proposes a novel adaptive load blinder for distance protection. A distance relay can provide remote backup protection by zones 2 and 3, but it may mal-operate under heavy loading conditions and cause cascading trips in the network, which could further lead to a widespread blackout. To prevent cascading outages, load blinders or load encroachment elements are generally used to block the distance relay when there is heavy load in the system. However, these elements are not always able to discriminate heavy loading conditions from fault conditions, especially for heavy loads with low power factors or faults with fault resistance. This paper presents a novel load blinder scheme for distance protection by using artificial neural network (ANN). Test results show that the proposed ANN-based load blinder scheme is able to discriminate between different heavy loads with a wide range of power factors and different faults with fault resistance.

Secure Remote Backup Protection of Transmission Lines Using Synchrophasors

We consider the problem of detecting a fault on a transmission line from the residual vector of a synchrophasor state estimator (SynSE). For a transmission line under fault, we identify six operating modes depending upon location of the phasor measurement units (PMUs). We show that in five operating modes, the fault is seen in the residual vector while in one mode, the fault will not reflect in the residual vector. The analysis leads us to propose a remote backup protection scheme for supervised zone-3 operation of distance relays. In case of inadequate PMU penetration in the system, the implementation of SynSE can even be restricted to a small subsystem of critical lines.