Designing a Protection Scheme in Micro-Grid Systems with DG Using Central Protection Unite and Multiple Setting Group Protection Relays

Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays and to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is also evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection stability and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system stability, output settings for relays in all cases achieved our constrains.

Operation Control Method of Relay Protection in Flexible DC Distribution Network Compatible with Distributed Power Supply

A novel operation control method for relay protection in flexible DC distribution networks with distributed power supply is proposed to address the issue of inaccurate fault location during relay protection,leading to poor performance.The method combines a fault-tolerant fault location method based on long-term and short-term memory networks to accurately locate the fault section.Then,an operation control method for relay protection based on adaptive weight and whale optimization algorithm(WOA)is used to construct an objective function considering the shortest relay protection action time and the smallest impulse current.The adaptive weight and WOA are employed to obtain the optimal strategy for relay protection operation control,reducing the action time and impulse current.Experimental results demonstrate the effectiveness of the proposed method in accurately locating faults and improving relay protection performance.The longest operation time is reduced by 4.7023 s,and the maximum impulse current is limited to 0.3 A,effectively controlling the impact of large impulse currents and enhancing control efficiency.

The Automated System of Unified Templates as an Element of Trainability of Microprocessor Relay Protection Devices

The article discusses the possibility of further modernization of the standard microprocessor relay protection of AC overhead system feeders DPA-27.5-TNF, which is operated on the Trans-Baikal Railway by creating an additional automated system of unified templates necessary for the occurrence of “trainability” elements. The templates will be formed via a separate dedicated channel for transmission, processing and storage of the necessary information, not related to the operation of the terminal, with its subsequent visualization at the workplace of the duty personnel of traction substations, together with information from the “GID” software received via another dedicated wired channel. With the help of such a base of unified preset templates, in the future, it will be possible not only to identify the specific causes of each emergency shutdown but also to reduce their number by dynamically adjusting the existing presets of the standard operation algorithm.

Serial Failure Diagnosis of a Transmission Line Protection Relaying System by Petri Nets

With the development of large-scale complicated modern power systems, the requirement for the associated protection scheme tends to be more stringent and its combination more complex. However, it is very difficult to figure out the factors of failure of such systems. This paper proposes a Petri net model of a transmission line protection relaying system, including three types of relays as well as an automatic reclosing device, and shows how to diagnose serial failure of the system by analyzing invariant sets of the model. Furthermore, it gives four basic types of failure sequences and its execution is much more intuitive and effective than the traditional method.

Overview of Analysis on State Evaluation of Relaying Protection System

With the rapid development of the smart grid, it is necessary to do good corresponding work in relaying protection so as to meet the overall requirements of the smart grid better. So we must focus on the state division, risk analysis and fault diagnosis methods in the relaying protection system, in the basis of fully understanding the advantages and disadvantages of relaying protection system, and then improve the problems existing of relaying protection system at this stage according to the actual situation. This paper aims at the overview of analysis on state evaluation of relaying protection systems.

Design analysis and its application of M out of N in reactor protection system

The reliability and availability of the reactor protection system （RPS） can be improved by using M out of N judg- ment system. By analyzing two quantitative indicators, the rate of refusal to operate and mal-operation rate, a strict math- ematical formula and an approximate calculation are stated. The differences of a series of judgment systems are discussed on condition that the unsafe failure probability and the security failure probability are both 0.1. Based on given parameters （A, B,P, Q）： A is upper limit of the refusal rate for the RPS, B is upper limit of the real-operation rate, P and Q are basic protection unit rates corresponding to refusal rate and mal-operation rate, respectively. According to these parameters, the values of N and M can be solved.

Impacts of Large-scale Wind Power Grid Integration on Relay Protection and Countermeasures

Several large-scale wind turbine tripping accidents occurred in Jiuquan wind power base in 2011.According to the on-site survey and analysis of these accidents related to relay protection,causes were found to be the collection system defects and low correct operation rate of small current grounded line selectors of the unearthed neutral point collection system.By referring to both the characteristics of Jiuquan wind power base and arrangement of relay protection,the short-circuit features of wind power and its impacts on relay protection are analyzed.The collection system and the retrofit of the small current grounded line selector are improved by specific countermeasures.Finally,further research subjects are put forward.

The Influence of Abnormal Data on Relay Protection

The parameters of abnormal data are defined and their influence on the original data and Fourier Algorithm is studied. A formula is proposed to quantify how the abnormal data influences the amplitude calculated by Fourier Algorithm. Two simulation models are established in Matlab to study the influence of abnormal data on relay protection. The simulation results show that the abnormal data can make distance protection extend the fault’s influence and make over current protection start by error.

Research on Reliability of Relaying Protection in Smart Substation

Research on reliability of relaying protection in smart substation not only has a positive effect on the rational configuration scheme of relaying protection in smart substation, but also can promote the stability and safety of the overall operation of power system. There are many reliability strategies for relaying protection in smart substation. In practice, the key points of relaying protection should be clarified. Based on the reality, the protection configuration should be strengthened;the voltage limited delay should be used for protection, and the protection configuration scheme of actual lines should be paid attention to, so as to improve the reliability of relaying protection in smart substation and promote the realization of stable and sustainable development of power system and smart substation.

Research on the Process Layer and Substation Layer Relay Protection in Smart Substation Relay Protection

The intelligent substation relay protection facility is a fundamental element in construction of modern power system,based on the principles of flexibility,security and accuracy,and it can be divided into process layer and substation layer according to specific equipment.The former is suitable for individual sampling of disposable equipment,can be separated from the base station synchronization sampling,with the help of synchronous digital system and ping-pong algorithm to achieve synchronization of the overall sampling,that is to take the distribution protection components,through the separate transmission medium to realize the information transmission;the latter is for variable power plant components centralized backup protection,taking online real-time tuning technique.

Autonomous Optimal Coordination Scheme in Protection System of Power Distribution Network by Using Multi-Agent Concept

A protection system using a multi-agent concept for power distribution networks is proposed.Every digital over current relay(OCR)is developed as an agent by adding its own intelligence,self-tuning and communication ability.The main advantage of the multi-agent concept is that a group of agents work together to achieve a global goal which is beyond the ability of each individual agent.In order to cope with frequent changes in the network operation condition and faults,an OCR agent,proposed in this paper,is able to detect a fault or a change in the network and find its optimal parameters for protection in an autonomous manner considering information of the whole network obtained by communication between other agents.Through this kind of coordination and information exchanges,not only a local but also a global protective scheme is completed.Simulations in a simple distribution network show the effectiveness of the proposed protection system.

Impact Analyses of Wind Farm on Performances of Transmission Line Relay Protection

A simulation system for power grid with concentrated large-scale wind farm integration is established based on the electro-magnetic transient model of wind turbine equipped with doubly-fed induction generator (DFIG),which is built by real-time digital simulator (RTDS).Using the hardware communication interface of RTDS,a closed-loop testing experiment is accomplished to study the impacts of large-scale wind farms on the existing relay protection devices for wind farm outgoing transmission line.This paper points out problems existing in current relay protection devices as follows:fault phase selector can select unwanted phase due to the changes of fault features caused by special network connection of wind farms;blocking condition for distance protections needs to be re-examined due to the weak power-feed characteristics of wind farms;and power frequency parameter based relay protection devices cannot accurately operate due to the special transient voltage and current characteristics of wind farms during fault period.Results lay the foundation for improving the performances of the existing relay protection device and developing new principle relay protection.

A Compound Relay Protection Operation Criterion Based on Kirchhoff’s Current Law and Abnormal Data Detecting Algorithm

A compound relay protection operation criterion is proposed based on Kirchhoff’s Current Law and abnormal data detecting algorithm. The abnormal data detecting algorithm are proposed after deep research on the abnormal data properties. The current transformer status monitoring system and current phase angle detecting system is introduced. A simulation model containing different power sources and loads is established in Matlab. The simulation results show that this compound criterion can work quickly and reliably in all conditions.

Reliability analysis for vertical integration of protection,measurement,merge unit,and intelligent terminal device

The reliability analysis of vertically integrated protection devices is crucial for designing International Electrotechnical Commission(IEC)61850-based substations.This paper presents the hardware architecture of a four-inone vertically integrated device and the information transmission path of each function based on the functional information transmission chain of protection devices,measurement and control devices,merging units,and intelligent terminals.Additionally,a reliability analysis model of the protection device and its protection system is constructed using the fault tree analysis method while considering the characteristics of each module of the vertically integrated device.The stability probability of the protection system in each state is analyzed by combining the state-transfer equations of line and busbar protection with a Markov chain.Finally,the failure rate and availability of the protection device and its protection system are calculated under different ambient temperatures using a 110 kV intelligent substation as an example.The sensitivity of each device module is analyzed.

Reliable Remote Relay Protection in Smart Grid

As the false trips of remote protection relays are among the main reasons behind cascading blackouts, it is critical to design reliable relay protection. Even though common protection schemes on traditional power systems have been investigated for a few decades, cascading failures in recent years indicate more research needed in this area. Consequently, researchers have proposed agent-based methods on the Smart Grid （SG） to address this issue. However, these existing agent-based methods simply use TCP protocol without considering real-time communication requirements （such as bandwidth and delay）. To deal with this issue, several methods for efficient network resource management are proposed. Furthermore, these existing methods do not consider the potential issues in practical communication networks, which may result in delay violation and trigger relay false trips. We have discussed simple backup solutions in the previous work. In this paper, in addition to network efficiency, we focus on improving the system reliability by exploring known power system information and minimizing the chances of false trips of important remote relays, e.g., defining power line priorities based on their importance. Moreover, to further improve the. system reliability, we also in- vestigate the peer-to-peer protection approaches to address the single point of failure of centralized control center.

A Design of 220 kV Line Protection Action Deduction System Based on Numerical Simulation

Accurate conditions monitoring and early wrong action warnings of relay protection in the Smart Substation is the basic guarantee to realize the normal operation of primary and secondary system of the power grid.At present,the traditional operation and maintenance monitoring methods of relay protections have poor timeliness,while some automatic monitoring methods have insufficient early warning performance,and lack the online action deduction function independent of the actual device.In this paper,a design method of integrated action deduction system including protection logic reasoning and software and hardware operation condition is proposed.The system can receive real-time operation information of protection online,simulate different types of faults,and output the recording information of sub modules belongs to the action deduction system.It can realize the online monitoring of device faults such as deducing the correctness of setting values at a certain time in the future,giving the wrong action warnings and predicting the probability of them as well,which effectively improves the operation and maintenance efficiency of the secondary system in the intelligent substation.

Comprehensive Automation of Microprocessor Protection Relay Terminals Operated on AC Railways

The article discusses the possibility of a potential reduction in the number of operations of microprocessor relay protection of feeders of the contact network of AC railways TsZA-27.5-FKS (FTS) for unknown reasons. Real statistics on the number of microprocessor relay protection operations at the Buryatskaya traction substation are presented, simulation of the real train situation (in accordance with the regime maps of the throughput capacity of the sections of the Trans-Baikal railway) was carried out in the specialized software complex “KORTES”. Based on the results of the analysis of simulation modeling, the process of forming a unified template of settings using neural network technologies is considered, which characterizes only this specific regular train situation. To protect objects in the event of pre-emergency and emergency modes of operation of the traction power supply system, a variant of changing the standard operation algorithm of the TsZA-27.5-FKS (FTS) terminal by introducing additional blocks for calculating the predictive functions of current and voltage has been proposed.

A Study on the Protection Relay Test and Analysis Method of AC Electric Railway Substation

Since opening of the Korean high-speed railway in 2004,the rate of electrification has been increasing rapidly,and safety of the supply of AC railways has become very important.And the digital protection relays in railway feeding system need more attention with the expansion of unmanned SSs(substations)and digital SSs.For accident prevention,it is necessary to develop accurate modeling and simulation technology for railway feeding devices of electric railway.And it is also important to continuously improve test methods and develop excellent relay algorithms and apply them to the protection system to prepare for unexpected accidents.In this study,after reduced modeling the AC railway power supply system using PSCAD/EMTDC(Power Systems Computer Aided Design/Electromagnetic Transient DC Analysis),the results were compared and verified with the numerical calculation using the symmetric coordinate method.It also presents a method of using the verified results for simulation and education for various railway accidents.This study result will be used for the construction of new lines as well as existing lines in the future railway business.

A Testing Method for Ratio Restraint Characteristics of Differential Relay Protection of Transformers

In this paper, a method to calculate the slope of the ratio restraint characteristic of a transformer differential relay protection is proposed. The method allows using some concise but effective means to get the slope. Modulating the argument of current output from ONLLY testing equipment can make the relay protection device operate, thus, the data used for calculation would be obtained naturally after several trails. In order to make sure how effective that method could be, some experiment data is given as well.

Fault Detection and Protection System of Electric Railway Substation

The industrial power systems are moving to digital networks,and unmanned systems are increasing recently with the technological development of information and communication technology.In particular,reliability of system operation is very important for stable power supply.Most industrial power distribution facilities use a 154 kV or 22.9 kV extra HV(high voltage)power system,and a special monitoring system is required because a large loss occurs when an error occurs in the power facility in the field.Although digital protection relay(IED;intelligent electronic device)and FR(fault recorder)are applied to the field to protect the power system,various improvement activities are still ongoing.In this paper,a 22.9 kV high-voltage panel and its test bed,which are widely used in railway stations,tunnels,substations and large plants,were tested as test subjects.The developed fault detection system automatically starts the AL(auto-lock)circuit or outputs an alarm signal to user by monitoring in real time problems such as CT(current transformer)-open and poor-contact that the existing digital protection relay cannot cover.In addition,it is intended to increase the safety and reliability of the power system by blocking various accidents in the system in advance and accurately analyzing the causes of faults with the developed fault detection system.