Teaching power system protection with industry's cooperation

Directional overcurrent and earth-fault protections for a biomass microgrid system in Malaysia

The analysis of unbalanced power systems depends usually on transformation methods by which the phase quantities are substituted by, for example, symmetrical component quantities. These transformations had the computational advantages in the past, but with the use of digital computer, they no longer appear to be necessary. In this paper the analysis of power system faults including the simultaneous ones has been undertaken with the help of phase coordinates, i. e., the actual system phase voltages, currents and impedances. This approach is found to be simple and readily adaptable to digital computer techniques. Symmetrical components are, however, used as a measure of the system unbalance.

With the high penetration of Renewable Energy Sources (RES) in power systems, the short-circuit levels have changed, creating the requirement for altering or upgrading the existing switchgear and protection schemes. In addition, the continuous increase in power (accounting both for generation and demand) has imposed, in some cases, the need for the reinforcement of existing power system assets such as feeders, transformers, and other substation equipment. To overcome these challenges, the development of superconducting devices with fault current limiting capabilities in power system applications has been proposed as a promising solution. This paper presents a power system fault analysis exercise in networks integrating Superconducting Cables (SCs). This studies utilized a validated model of SCs with second generation High Temperature Superconducting tapes (2G HTS tapes) and a parallel-connected copper stabilizer layer. The performance of the SCs during fault conditions has been tested in networks integrating both synchronous and converter-connected generation. During fault conditions, the utilization of the stabilizer layer provides an alternative path for transient fault currents, and therefore reduces heat generation and assists with the protection of the cable. The effect of the quenching phenomenon and the fault current limitation is analyzed from the perspective of both steady state and transient fault analysis. This paper also provides meaningful insights into SCs, with respect to fault current limiting features, and presents the challenges associated with the impact of SCs on power systems protection.

Electric Power. Electric Power Utilization. Transformers. Transmission Systems. Substations. Distribution Systems. Electric Power Utilization. Power System Analysis and Simulation. Power System Protection. Power System Transients. Power System Dynamics/Stability. Power System Operation/Control. Power System Planning (Reliability). Power Electronics. Power Quality.

In this paper, we adopt a novel approach to the fault analysis of complex electric power systems. Electric power system is one of the most complex artificial systems in the world. Its ...

Mixed three-phase and six-phase power system analysis using symmetrical components method

This research focuses on the study of the directional phase overcurrent relaying concept that can be briefly explained by the relay tripping whenever the faulted current exceeds a pre-determined pick up value in a specific predefined direction, in order to isolate only the faulted part of the network. The Directional Phase Overcurrent Protection appears more important in the distribution system when the Overcurrent protection is the main protection. Any glitch in its setting can lead to opening the circuit in the non-faulty area or can perform non-trip in the faulty area. As an example in Algeria, this problem happens repeatedly in the plurality distribution substations. This reliable and selective protection is generally used in multisource networks, parallel transmission lines and mesh distribution networks. It is mainly characterized by its Maximum Torque Angle and Relay Characteristic Angle (RCA), also known as the directional angle as it decides the direction of the tripping zone. The variation of the RCA setting has a direct impact on the sensitivity operation of the relay (45 degrees' maximum sensitivity operation for any type of fault). Tests have been performed on The Four Step Directional Phase Overcurrent Protection Function of the Line Distance Protection REL670 ABB IED numerical relay. On one hand, the 51/67 ANSI protection has been tested and results were discussed. On the other hand, different cases of RCA settings were evaluated under fault to showcase that the 45-degree angle is the best applicable value for a maximum sensitivity.

Power System Fault Analysis and Protection

This research work estimates the effect of harmonics on symmetrical components of power network using least square method. Symmetrical component analysis of power line faults has been considered an effective tool for the design and control of power devices since their introduction. Harmonics present in power system disturb the operation of analogue protective devices. Moreover, the harmonics deteriorate the power quality, increase power loss, decrease appliances life and ultimately decrease the reliability of power system. A microprocessor based technique to estimate the value of symmetrical components under abnormal conditions in the presence of harmonics is investigated and simulated. The given technique deploys method of least squares in order to estimate the magnitude of symmetrical components. Simulation of proposed model is carried out in MATLAB/SIMULINK.

The paper presents the procedure of directional ground overcurrent protection setting calculation in the transmission network by using classical calculation procedure and by using an advanced algorithm of differential evolution. To meet the basic requirements of relay protection systems such as speed, selectivity, coordination and sensitivity, the conditions that need to be considered when setting directional ground overcurrent protection are defined. By using the optimization method, the problem was solved in two ways. In the first case, the settings are designed to minimize the total response time of directional ground overcurrent protection to remote-end high-resistance faults, whereas in the second case the settings are designed so that the maximum response time to remote-end high-resistance fault is minimal. The results obtained using the classical approach are compared with the results obtained using the optimization method and the advantages and disadvantages of both approaches are highlighted.

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.<p class="MsoNormal" style="text-align: justify; text-indent: .5in;"><em><span style="font-size: 9.0pt; font-family: 'Arial','sans-serif'; color: black;">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.</span></em></p><!--[if gte mso 9]><xml>
 <o:OfficeDocumentSettings>
 <o:RelyOnVML/>
 <o:AllowPNG/>
 </o:OfficeDocumentSettings>
 </xml><![endif]--><!--[if gte mso 9]><xml>
 <w:WordDocument>
 <w:View>Normal</w:View>
 <w:Zoom>0</w:Zoom>
 <w:TrackMoves/>
 <w:TrackFormatting/>
 <w:PunctuationKerning/>
 <w:ValidateAgainstSchemas/>
 <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid>
 <w:IgnoreMixedContent>false</w:IgnoreMixedContent>
 <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
 <w:DoNotPromoteQF/>
 <w:LidThemeOther>EN-US</w:LidThemeOther>
 <w:LidThemeAsian>X-NONE</w:LidThemeAsian>
 <w:LidThemeComplexScript>X-NONE</w:LidThemeComplexScript>
 <w:Compatibility>
 <w:BreakWrappedTables/>
 <w:SnapToGridInCell/>
 <w:WrapTextWithPunct/>
 <w:UseAsianBreakRules/>
 <w:DontGrowAutofit/>
 <w:SplitPgBreakAndParaMark/>
 <w:EnableOpenTypeKerning/>
 <w:DontFlipMirrorIndents/>
 <w:OverrideTableStyleHps/>
 </w:Compatibility>
 <m:mathPr>
 <m:mathFont m:val="Cambria Math"/>
 <m:brkBin m:val="before"/>
 <m:brkBinSub m:val="--"/>
 <m:smallFrac m:val="off"/>
 <m:dispDef/>
 <m:lMargin m:val="0"/>
 <m:rMargin m:val="0"/>
 <m:defJc m:val="centerGroup"/>
 <m:wrapIndent m:val="1440"/>
 <m:intLim m:val="subSup"/>
 <m:naryLim m:val="undOvr"/>
 </m:mathPr></w:WordDocument>
 </xml><![endif]--><!--[if gte mso 9]><xml>
 <w:LatentStyles DefLockedState="false" DefUnhideWhenUsed="true"
 DefSemiHidden="true" DefQFormat="false" DefPriority="99"
 LatentStyleCount="267">
 <w:LsdException Locked="false" Priority="0" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="Normal"/>
 <w:LsdException Locked="false" Priority="9" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="heading 1"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 2"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 3"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 4"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 5"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 6"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 7"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 8"/>
 <w:LsdException Locked="false" Priority="9" QFormat="true" Name="heading 9"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 1"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 2"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 3"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 4"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 5"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 6"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 7"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 8"/>
 <w:LsdException Locked="false" Priority="39" Name="toc 9"/>
 <w:LsdException Locked="false" Priority="35" QFormat="true" Name="caption"/>
 <w:LsdException Locked="false" Priority="10" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="Title"/>
 <w:LsdException Locked="false" Priority="1" Name="Default Paragraph Font"/>
 <w:LsdException Locked="false" Priority="11" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="Subtitle"/>
 <w:LsdException Locked="false" Priority="22" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="Strong"/>
 <w:LsdException Locked="false" Priority="20" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="Emphasis"/>
 <w:LsdException Locked="false" Priority="59" SemiHidden="false"
 UnhideWhenUsed="false" Name="Table Grid"/>
 <w:LsdException Locked="false" UnhideWhenUsed="false" Name="Placeholder Text"/>
 <w:LsdException Locked="false" Priority="1" SemiHidden="false"
 UnhideWhenUsed="false" QFormat="true" Name="No Spacing"/>
 <w:LsdException Locked="false" Priority="60" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light Shading"/>
 <w:LsdException Locked="false" Priority="61" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light List"/>
 <w:LsdException Locked="false" Priority="62" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light Grid"/>
 <w:LsdException Locked="false" Priority="63" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Shading 1"/>
 <w:LsdException Locked="false" Priority="64" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Shading 2"/>
 <w:LsdException Locked="false" Priority="65" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium List 1"/>
 <w:LsdException Locked="false" Priority="66" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium List 2"/>
 <w:LsdException Locked="false" Priority="67" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Grid 1"/>
 <w:LsdException Locked="false" Priority="68" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Grid 2"/>
 <w:LsdException Locked="false" Priority="69" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Grid 3"/>
 <w:LsdException Locked="false" Priority="70" SemiHidden="false"
 UnhideWhenUsed="false" Name="Dark List"/>
 <w:LsdException Locked="false" Priority="71" SemiHidden="false"
 UnhideWhenUsed="false" Name="Colorful Shading"/>
 <w:LsdException Locked="false" Priority="72" SemiHidden="false"
 UnhideWhenUsed="false" Name="Colorful List"/>
 <w:LsdException Locked="false" Priority="73" SemiHidden="false"
 UnhideWhenUsed="false" Name="Colorful Grid"/>
 <w:LsdException Locked="false" Priority="60" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light Shading Accent 1"/>
 <w:LsdException Locked="false" Priority="61" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light List Accent 1"/>
 <w:LsdException Locked="false" Priority="62" SemiHidden="false"
 UnhideWhenUsed="false" Name="Light Grid Accent 1"/>
 <w:LsdException Locked="false" Priority="63" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Shading 1 Accent 1"/>
 <w:LsdException Locked="false" Priority="64" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium Shading 2 Accent 1"/>
 <w:LsdException Locked="false" Priority="65" SemiHidden="false"
 UnhideWhenUsed="false" Name="Medium List 1 Accent 1"/>
 <w:LsdException Locked="false" UnhideWhenUsed="false" Name="Revision"/>
 <w:LsdException Locked="false" Priority="34" SemiHidden="false"
 UnhideWhenUsed="f

In today’s world electric power demand is increase steadily. In order to meet this increasing demand superconducting cable can be use instead of conventional AC cable in the power system. The Superconducting cable has some different characteristic than conventional AC cable. If this cable is installed in the power system, then there are some effects introduced on the fault current level. These effects on the fault current level can further have an impact on the power system protection. So there is a need to analyze the impact of a superconducting cable on power system protection and determine its impedance under a fault condition. This paper presents the impacts of the fault current level on a superconducting cable under fault condition in power system. Different types of fault are present in this paper like LG fault, LL fault, LLG fault, LLL fault.

Circuit breakers are widely applied in power system protection by interrupting fault current. Among all types of circuit breakers, we focus on the modeling of thermal-magnetic circuit breakers in this paper. Data regression and curve fitting methodologies are employed to study the manufacturer's time/current data. A brand new simulation model that contains probability tools is developed to realistically describe the tripping characteristics, and a product failure rate is also considered to reflect possible circumstances in real-world application of the thermal-magnetic circuit breakers. A simulation testbed system is included for the purposes of illustration and validation.

Direct stability analysis using an energy function has recently been widely used for angular and voltage stability analysis in electric power systems. Considerable efforts have concentrated on seeking energy functions for lossy power systems, accomplished only for the simple two-bus system. A new approach is presented to derive an energy function by using the complex integral of bus current equations with respect to bus voltages. Under an assumption that all transmission lines have a uniform R/X ratio, it is shown that the energy function can be developed for multimachine power systems with losses. The proposed energy function is tested on sample systems by comparing the time simulation method, which shows the validity of the proposed method.

For power system protection, the distance relay settings are important. Apparent factor is a necessary parameter in distance relay settings. Apparent factors have to be calculated when setting the distance relays and doing the resetting in case of configuration change in power system. The problem is that the current method to calculate apparent factor requires tools and plenty of time to do fault analysis and this method is complex especially in case of configuration change. Therefore this paper proposes a fast algorithm to calculate apparent factor without the fault analysis. Test results prove that this algorithm is simple and accurate by simulation.