Performance Of Power System Protection Research Articles

Influence of process bus on performance of power system protection

The development of substation operations under open standards has ensured interoperability among technology manufacturers and has led to system management evolution. Implementing a Process Bus (PB) and its related technologies represents the future of power systems protection. The release of the IEC61850-9-2 sampled values protocol has allowed the replacement of the conventional measurement method by an ethernet-based system at substation yards. This study focuses on the PB implementation effects such as the trip time delay and possible time shift over the protection system performance. The paper points out aspects that should be considered through the engineering process and design, considering the two PB standards, IEC61850-9-2LE and IEC61869-9. A test architecture was composed of a conventional relay, and two PB relays synchronized using the IEEE-1588-Precision Time Protocol (PTP). Four tests were carried out, including a software simulation and field-collection data. The two PB standards presented similar results during the tests. The relay signal resampling results in time shifts that should be properly compensated, and the digitalization delays found can occasionally add more than 9 ms in the final trip time and must be considered in protection studies prior to implementation. Otherwise, it can significantly impact on the project of the power system.

Analysis on the Impact of Renewable Energy to Power System Fault Level

Distributed Generation is generation of electricity from renewable energy resources, located closer to the customers or loads. Installation of Distributed Generation could improve voltage and power quality, mitigate voltage sags, minimize transmission system congestion, and provide more affordable capacity for utilizing renewable energy resources. However, high penetration of Distributed Generation to the existing national grid system may contribute several impacts including fault level, as well as the performance of power system protection. Monitoring of fault level is important in power system protection in order to sustain the health of power system networks. This paper investigates the impact of installing Distributed Generation to power system fault level. Three-phase symmetrical fault is simulated and analyzed for various sizes of distributed generation in IEEE 30 bus system using Power System Simulation for Engineering (PSS/E) software. Distributed Generation is generation of electricity from renewable energy resources, located closer to the customers or loads. Installation of Distributed Generation could improve voltage and power quality, mitigate voltage sags, minimize transmission system congestion, and provide more affordable capacity for utilizing renewable energy resources. However, high penetration of Distributed Generation to the existing national grid system may contribute several impacts including fault level, as well as the performance of power system protection. Monitoring of fault level is important in power system protection in order to sustain the health of power system networks. This paper investigates the impact of installing Distributed Generation to power system fault level. Three-phase symmetrical fault is simulated and analyzed for various sizes of distributed generation in IEEE 30 bus system using Power System Simulation for Engineering (PSS/E) software. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

Improving the performance of power system protection using wide area monitoring systems

Wide area monitoring (WAM) offers many opportunities to improve the performance of power system protection. This paper presents some of these opportunities and the motivation for their development. This methods include monitoring the suitability of relay characteristics, supervisory control of backup protection, more adaptive and intelligent system protection and the creation of novel system integrity protection scheme. The speed of response required for primary protection means that the role WAM in enhancing protection is limited to backup and system protection. The opportunities offered by WAM for enhancing protection are attractive because of the emerging challenges faced by the modern power system protection. The increasingly variable operating conditions of power systems are making it ever more difficult to select relay characteristics that will be a suitable compromise for all loading conditions and contingencies. The maloperation of relays has contributed to the inception and evolution of 70 % of blackouts, thus the supervision of the backup protection may prove a valuable tool for preventing or limiting the scale of blackouts. The increasing interconnection and complexity of modern power systems has made them more vulnerable to wide area disturbances and this has contributed to several recent blackouts. The proper management of these wide area disturbances is beyond the scope of most of the existing protection and new, adaptive system integrity protection schemes are needed to protect power system security.

Fast, <italic>In Situ</italic> Demagnetization Method for Protection Current Transformers

This paper proposes a fast, in situ demagnetization method for protection current transformers (CTs). Simulations show that the method can automatically demagnetize a CT within 300 ms in situ , i.e., while the CT is deenergized but still connected to the substation. Therefore, unlike existing methods that require the CT to be disconnected from the substation, this new method can be used to demagnetize a CT during a short interruption, e.g., the time it takes an autorecloser to operate, rather than requiring an extended outage of the substation. This will dramatically increase the number of opportunities for the demagnetization of protection CTs, which will alleviate the threat of remanent flux in the CT from causing saturation and compromising the performance of power system protection. Furthermore, by demagnetizing the CT in situ , the method avoids the risk of the improper reconnection of the CT, creating a source of hidden failure. The new method uses the existing dc voltage source in the substation to charge the CT and a parallel-connected inductor. An automatic control scheme is presented that manages the charge/discharge of the inductor, and thereby the demagnetization, by controlling three switches that reconfigure an $RLC$ circuit. The additional hardware required by the method is the three switches, the switch controller, and the $RLC$ circuit. The new method is tested for different hysteresis characteristics, levels of remanent flux, and errors in the assumed element parameters and measured hysteresis characteristics using EMTP-RV simulations. The results indicate that the proposed method can quickly and effectively demagnetize a protection CT in situ .

Flexible Model-Based Alarm Processing for Protection Performance Assessment and Incident Identification

This paper presents a system, PSDiagnosis, designed to automate the analysis of Supervisory, Control and Data Acquisition (SCADA) data for the assessment of power system protection performance. The model-based system exploits the theory of diagnosis through use of the General Diagnostic Engine (GDE). Models of protection devices combined with the GDE provide the ability to diagnose the maloperation of protection equipment: including multiple faults, missing alarms and new or previously unknown faults. The base requirements were determined in conjunction with a transmission system operator within the U.K. with a major task identified in reducing software maintenance while maintaining an accurate diagnostic result. The novel approaches taken in this system include the provision of dynamically configurable protection device models for reuse on a multitude of different network connections and the modification of the GDE to identify the occurrence of missing alarms. The approach taken ensures that the system is easy to update as the network, equipment and data formats evolve. This paper discusses the requirements, development and application of PSDiagnosis to the transmission network and the experience and results gained from the implementation of an online prototype.

Impact of Distributed Generations on Power System Protection Performance

Though distributed generators (DGs) have significant economic and environmental benefits, increased penetration of DGs will impose significant technical barriers for the efficient and effective operation of bulk power systems. Increased fault current contribution and load flow changes are the major two impacts on utility systems, and these will affect existing protective relaying, especially overcurrent relays. To ensure safe and selective protection relay coordination, the impact of DGs should be taken into account when planning DG interconnection. This paper presents an introduction of DGs and an overview of the impacts of DGs on system protection relay coordination. Several protection issues are identified to study the requirements for protection in the presence of DGs are also discussed. Key words: Distributed generator (DG), protection coordination, distribution network, overcurrent relay.