Protective Relay Settings Research Articles

An Algorithm for Transmission Distance Relay Setting Calculation Under Network Topology Change

Power systems are being expanded day by day with a more complex structure. The system topology always changes due to faults and/or operation requirements. Therefore; malfunctions might occur in the protection system which is one of the most important components for the system reliability, stability and economic operation. Distance protection relays fulfil the main protection function of the power transmission lines. In this study, an algorithm is created which recalculates the distance protection relay setting values depending on the topological changes of the network. The algorithm verified by testing on a selected area from the Turkish National Power Transmission System which comprises 154 kV 28 buses. Modelling of the power system carried out with Dig silent Power factory software. The algorithm is created in the DPL (Dig silent Programming Language) platform.

Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

The relay protection settings performed in the largest thermal powerplant (TE 'Nikola Tesla B') are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according to which the calculations are done are described. Criteria used to provide the protection to fulfill the backup protection role in the event of malfunction of the main protection of the transmission system. are clarified. The calculation of all protection functions (32 functions) of generator B1 were performed in the project 'Coordination of relay protection blocks B1 and B2 with the system of excitation and power system protections -TENT B'.

Adaptive Setting and Simulation of Distance Protection Relay in a Long Transmission System Connected to an Offshore Wind Farm

Offshore wind power has become the focus of the world's renewable energy development. In Taiwan, several demonstration offshore wind turbines will be scheduled to be established by 2015, and more than 300MW capacity of offshore wind farm to be installed by 2020. As the penetration level of wind energy increases, more reliable protection systems for offshore wind farms are required. The wind farm protection system is usually divided into different protection zones including the wind farm area, wind farm collection system, wind farm interconnection system and the utility area. Different protective zones have different protection schemes and relay settings. This project has proposed an adaptive distance relay that protects submarine cables between an offshore wind farm and an AC grid. The double-circuit submarine cables that connect offshore wind farm in Penghu and Taiwan grid will be utilized as an example. First, the apparent impedance of the relay is mathematically derived using a detailed equivalent circuit model, and the characteristic trip boundaries of the relay in various scenarios are obtained. The nonlinear characteristics of the trip boundaries that are used in a typical distance relay with four protection zones will be discussed. Furthermore, the effects of the uncontrollable factors on the performance of a distance relay have been considered into the simulations. These system disturbances include wind speed variation, system short circuit faults, or system component failures. These case studies have been presented using the simulation package to evaluate the feasibility of the distance relay setting that is developed in this project.

Algorithm and Recommendations for Setting Line Distance Relay Protection

In this paper author want to present new algorithm and recommendations for setting distance relay protection. This algorithm bases on technical effect criterion with using probability statistical method. Main approach is to study and develop technical effect criterion for selection of differential relay protection setting and technical efficiency criterion for estimating this setting. The probability statistical algorithms are used to calculate the above criteria.

The Risk Assessment of Power Plant Relay Protection Setting Value Based on the Monte-Carlo Simulation

发电厂继电保护定值一旦失效会引发输送功率的损失，甚至造成严重的停电事故。为了使继电保护定值科学有效，本文对保护定值进行了风险评估。首先基于蒙特卡洛法对保护定值的运行状态进行仿真模拟；然后提出了发电厂继电保护定值风险的定义及评估指标；最后利用实际算例验证了该方法的可行性。 Once the setting value of power plant relay protection becomes invalid, there must be losses of power, and it even causes serious outage. In order to make the setting value more utility, the risk assessment of setting value is presented in this paper. First of all, Monte Carlo method is used to simulate the states of setting values; then the definition and indicator of the risk assessment of setting value are introduced; at last, a practical example is used to verify the feasibility of the method proposed in this paper.

A Fault Equivalent Network Based Method for Calculating the Doubly Fed Wind Power Generator Short-circuit Currents

—Current research on short-circuit currents of the doubly fed induction generator is all based on the traditional flux analysis theory. In this article, a novel method to calculate the doubly fed induction generator stator and rotor short-circuit currents is proposed based on the fault equivalent network. First, the fault network is decomposed into a no-fault (normal operation) network and a fault supplementary network. On this basis, considering the influence of the terminal voltage phase jump and the rotor-side converter control, from the perspective of function decoupling, the fault supplementary network is further decomposed into the stator-side fault supplementary network and the rotor-side fault supplementary network. Laplace transformation is then used to calculate the current additions of the two fault supplementary networks. Thus, the analytical expressions of all currents under the grid symmetrical and asymmetrical short circuit could be derived. Finally, both simulation and dynamic experiment results verify that the doubly fed induction generator short-circuit current expressions derived with the proposed method are correct, which facilitates the short-circuit current calculation and relay protection setting of a power grid with a doubly fed induction generator connection.

Dynamic Phasor Modeling of Type 3 DFIG Wind Generators (Including SSCI Phenomenon) for Short-Circuit Calculations

Short-circuit modeling of wind generators is crucial to determine protective relay and control settings, equipment ratings, and to provide data for protection coordination. The short-circuit contribution of a Type 3 wind farm connected to a series-compensated line is affected by subsynchronous interactions, making it essential to model such behavior. Fundamental frequency models are unable to represent the majority of critical wind generator fault characteristics. The complete electromagnetic transient (EMT) models, though accurate, demand high levels of computation and modeling expertise. This paper proposes a novel modeling technique for a Type 3 wind farm based on the generalized averaging theory, where system variables are represented using time-varying Fourier coefficients known as dynamic phasors. The novelty and advantage of the proposed modeling technique is that it does not just include 60-Hz frequencies but also other dominant frequencies, such as 36 Hz, that are present due to the SSCI in the system. Methods currently used by the industry mostly rely on fundamental frequency-based analysis. Only the appropriate dynamic phasors are selected for the required fault behavior to be represented, improving computational efficiency. Once the SSCI behavior (waveforms showing resonant frequency at the point of common coupling) of a series-compensated Type 3 wind farm from real-time field data is available, the developed model could be used to simulate the scenario without necessarily having to know the exact control blocks of the wind generator controls. A 450-MW Type 3 wind farm, consisting of 150 units, was modeled using the proposed approach. The method is shown to be accurate for representing faults at the point of interconnection of the wind farm to the grid for balanced and unbalanced faults as well as for nonfundamental frequency components present in fault currents during subsynchronous interactions.

Research on Characteristics of Stator and Rotor Fault Current of DFIG

The abrupt dip of grid voltage would provoke a series of electromagnetic transient processes in stator and rotor of DFIG, which would threat the security of wind turbines fault ride through (LVRT) and stable operation of power system. Analyzing the fault current characteristics of DFIG is very useful to improve the LVRT strategy and adjust the relay protection setting of power system. In this paper, electromagnetic transient processes of DFIG are given a detail analysis after protection circuit of DFIG works due to the dip of three phase voltage in system. Then, the general expression of stator and rotor fault current is derived, and the validity of this method is verified. At last, the influences of the system short-circuit capacity and wind turbines accessing capacity on the fault current and system protections are analyzed when the wind turbines are accessed to the distribution network.

The Research on Relay Protection Settings On-Line Verification System Application in Smart Grid

The intelligrid-oriented on-line relay settings verification system based on EMS real-time data are discussed, with related software system designed and fulfilled. Firstly, the research background and current situation of on-line relay settings verification system are summarized. Secondly, the on-line relay settings verification system's general principle, hardware and software design are mainly discussed. And this paper shows the designed hardware structure diagram, the software structure diagram. And the flowchart of main procedure is given. Thirdly, the methods of dealing with EMS real-time data of the on-line verification system are discussed in detail. The verifying principles of sensitivity & selectivity of relay protection are given definitely. It is able to simulate two simultaneous faults, faults in network oscillation, and faults during auto-reclosing. It checks reliability & sensitivity of relay settings under these circumstances. Finally, considering substation-area and wide-area relay protections, this paper points out some key problems of on-line relay settings verification system to be resolved, and its application prospect.

Study and Application of Integrated Online Check of the Counties

In order to make the relay protection setting value online checking work more scientific and perfect, this paper studies the integration of county of relay protection setting value online verification scheme based on. Firstly, the county to achieve the integration constant value on-line check the general introduction, focuses on the display data acquisition and the checking calculation; then the county integration interface setting strategy of online check, describes the intelligent interface of intelligent don't know County, interface verification principle and interface design check the principle of selection; finally summing junction surface setting technique of on-line verification.

Relay Protection Setting Calculation and Analysis of Auxiliary Power System for Hydropower Plants

The configuration and setting calculation of auxiliary power protection are directly related to the regular and safe operation of the equipments, thereby affecting the security and stability of the power plant. The system features are analyzed in depth according to the operational requirements of auxiliary power system protection in Xiangjiaba hydropower plant ,the system model is built on the basis of the actual project, and a variety of short-circuit current calculations are carried out. At last, the setting of the auxiliary power system relay protection is completed. This thesis also proposes solutions to the emerging problems in the process of protection setting. The results of the setting have been applied to the actual operation and no misoperation or maloperation caused by improper constant setting value has occurred so far in Xiangjiaba hydropower plant.

Reliable Protective Scheme for Integrating Variable Capacity Micro Grids Using Superconducting Fault Current Limiters

Dispersed generations (DGs) have its vital importance in the increasing power demand scenario. The penetration of the new generating facilities like wind, solar power etc has serious effects on the stability and the reliability of the power system. As this penetration increases, there will be a corresponding increase in the fault current level of the system which could result in fault current over duty burden. Existing power system equipments like circuit breaker capabilities and protective relay settings which are already designed for a system without considering the DGs, will not have the required ratings to withstand this severe condition. Thus, the most important challenge is their reliable integration with the Main Grid. To overcome this problem, there is a need for protection system redesign or a complete system up-gradation, which could be very expensive. The use of Fault Current Limiters (FCLs) is one of the most economical and effective solutions for the above said problem. This paper discusses the use of Superconducting Fault Current Limiters (SFCLs) as a Unidirectional Fault Current Limiter (UFCL). SFCLs are the ‘invisible elements’ in the power system under normal operation and is visible only when a fault occurs. Through this paper, reliable integration schemes for the Variable Capacity Micro Grids (VCMGs)/Renewable Energy Generation (REG) using USFCL is introduced. Simulation studies were conducted using PSCAD and numerical analyses were done to explain the effectiveness of the proposed protective system. Also, a PSCAD model of USFCL for unsymmetrical fault analysis is proposed. The proposed integration schemes prove to be reliable as it ensures an improved power quality of the micro grid and retains the protective co-ordination of the relays, thus, helping in the use of the existing protective system effectively when the VCMGs/REG are installed in the power system.

Adaptive overcurrent relay coordination for off-peak loading in interconnected power system

Due to the substation automation, the supervisory control and data acquisition (SCADA) system is spreading that the protective relay settings can be modified through the network automatically. This work presents an overcurrent relay coordination decision for switching the relay settings to adaptive the off-peak loading in interconnected power system. Overcurrent relays (OCR) including directional and non-directional protective relays are widely applied in power system as main protective devices as they are reliable, cost effective and selective. Usually, the OCR protective coordination is coordinated at the time of maximum load and normal power supply, which may not be adaptive, as generating and load power are decreased significantly during the off-peak period of time compare to peak load that insufficient currents caused cascade lagging to activate OCRs. An example of single-ring interconnected power system was tested to demonstrate the coordination and confirm that the proposed approach method is practical during the off-peak time.

Adaptive Relay Setting for Distribution Systems Considering Operation Scenarios of Wind Generators

This paper presents a method for an adaptive relay setting for distribution systems with wind generators (WGs). The advanced distribution automation system (ADAS) is applied to monitor the operational status of WGs and line switches. For the change of operational status of WGs or network reconfiguration of distribution systems because of the operation of line switches, the function of the adaptive relay setting is activated by the ADAS control master station. Short-circuit analysis is performed to solve the magnitude and direction of fault-current flows. The protective relay settings are then accordingly revised and loaded to the protective relays along the feeder to achieve the adaptive fault protection. Sample distribution feeders with open- and closed-loop configurations are used to demonstrate the adaptive relay setting for distribution systems with various operational scenarios of WGs. It is concluded that the fault currents contributed by WGs must be included in the design of the tap/level settings of protective relays by the ADAS to achieve good protection of smart distribution systems.

Parameterization of a synchronous generator to represent a full-scale converter generator for fault studies

This paper addresses the representation of the full-scale converter generator technology by equivalent operational impedances valid for short-circuit current calculations. Modern wind power plants are required and designed to ride through faults in the network, subjected to fault clearing. Accurate knowledge of the wind turbine short-circuit current contribution is needed for component sizing and protection relay settings during faults within the wind power plant collector system or in the external networks. The industry standard employs software packages where generators are represented by their equivalent synchronous generator operational impedances, calculated according to standards or for electromagnetic simulation models, when studying fault currents and protection settings for wind power plant installations. Hence, it is of importance to represent non-synchronous wind generators also by an equivalent synchronous generator. The effectiveness of the proposed method has been validated by simulation and site measurements. Copyright © 2013 John Wiley & Sons, Ltd.

변전소와 차량간의 동기화를 통한 실시간 전차선로 임피던스 예측 기법 연구

This paper proposed a new real time catenary impedance estimation technique using synchronized power data from the measured data of operating vehicle and substation for catenary protective relay and fault locator setting. This paper presented estimation equation of catenary impedance using synchronized power data between substation and vehicle of AT feeding system for the performance verification of the proposed technique. Also AC feeding system is modeled through power analysis program and performance was verified through simulation according to various load changes. We verified that average 2.38%(distance equivalent 23.8 m) error appeared between the proposed estimation equation of catenary impedance and power analysis program simulation output in no connection double track system between up track and down track. Furthermore, We confirmed that estimation error is bigger depending on the increasing the distance from substation and vehicle impedance using only using vehicle current when calculating vehicle impedance in connection double track system between up track and down track. But, We confirmed that the proposed technique estimated accurately catenary impedance regardless of vehicle impedance and distance from substation.

A Research on Transmission Line Power Frequency Parameter Measurement

This paper aims at various problems encountered in the current power-frequency parameter measurements, analyzed the feasible solutions which not only effectively improved the accuracy of surveying data, but also provided necessary and accurate data for transmission line parameters for the calculation of stability of power system and relay protection setting, and a reliable theoretical basis for the calculation of electric power system and correct setting and selection of various switching equipment. It has been proved through practical engineering verification that, power-frequency parameter measurements has very important significance in improving the safe operation of the power system.

On-Line Verification of Relay Protection Setting Based on Transmission Contribution Degree

In this paper, a new method that is based on the transmission contribution degree is proposed, which can effictively imprve on-line verification of relay protection setting.Actually, all protection devices of a line are treated as a whole in this method. Furthermore, the network maximum flow and complex network theory are both applied in this method, which is on the view of the structural point of the grid. The importance index of protection device in a line is determined by the transmission contribution degree. As a result, on-line verification of relay protection setting is according to the descending order of the indexes. IEEE 39-bus system is used to simulate, on the whole, the simulation and analysis of the calculation results to verify the reasonableness and correctness of the method.

Risk Assessment of Relay Protection Setting Value in Power Plant

Power plant relay protection setting value of the hidden harm causes of relay protection device is not correct, safe and stable operation of the power plant. In this paper, from the angle of the safe operation of power plant, the hidden danger to plant with the protection setting is studied and then the risk evaluation method of power plant relay protection setting values of hidden trouble is proposed. From the power plant relay protection setting value considering two aspects of probability and consequences of potential outbreak of different values, value potential risk is considered, and of a certain power plant in Hubei was made the risk assessment and analysis, in order to verify the theoretical rationality and accuracy.

Improved Sequence Network Model of Wind Turbine Generators for Short-Circuit Studies

Protective relay settings for wind turbine generators often depend on short-circuit calculations performed using sequence network circuits in rms-based protection software. Traditional assumptions made in deriving the sequence network representation of induction machines result in some error in short-circuit calculations, which could potentially cause incorrect relay settings. A more accurate sequence network model of induction machines is derived in this paper to aid in short-circuit calculations in induction-generator-based wind plants. A rigorous mathematical approach to defining the stator short-circuit current equations under general faults is described and validated with transient simulations. The sequence network model of the induction machine is derived from the closed-form mathematical solutions. An example short-circuit calculation is performed on a simple network in this paper, and found to have a marked improvement in accuracy from traditional sequence network calculation methods for unbalanced faults. Resonant effects of power factor correction capacitors are also described.