Description:
This chapter presents a preliminary study conducted to improve photovoltaic (PV) cell conversion efficiency using MATLAB/Simulink platform. The study uses multi-junction solar cell and investigates the maximum performance compared with a conventional silicon PV cell. Maximum Power Point Tracker (MPPT) is applied to assess the conversion efficiency of the PV system. Study integrates thermoelectric generator (TEG) with PV modules because the PV cells work by converting high frequency irradiation where as a TEG has the ability to convert wasted low frequency heat to the electricity. The combination delivers more power and contributes to enhance the conversion efficiency of a PV system. The simulation results show that a tandem cell can provide a considerable higher power with a conventional PV cell operation.
Description:
Substation plays an important role in power system communications for safe and reliable operation of entire power networks. Substation communication networks are connected with various substation intelligent electronic devices (IEDs), which is substation systems lifeblood and the system availability is decided by its real-Time performance. International Electro-Technical Commission (IEC) has been developed the standards based on object-oriented technologies for substation automation. IEC 61850 protocol has been applied widely in substation communication applications. It presents new challenges to realtime performance simulation and testing of protective relays. In this paper, an optimized network engineering tool (OPNET) or Riverbed modeler simulation tool/ software has been used for the modeling of IED in substation level network. Based on the simulation results, different types of data stream have been discussed, such as, periodic data stream, random data stream and burst data steam. The typical studies using these models, to construct substation automation system (SAS) network on the OPNET modeler or Riverbed modeler was made to reveal the impact of each affecting parameter or factor to the real-Time performance of substation communications system, which is also incorporated in this report.
Description:
2015 Australasian Universities Power Engineering Conference: Challenges for Future Grids, AUPEC 2015
Description:
Substation plays an important role in power system communications for safe and reliable operation of entire power networks. Substation communication networks are connected with various substation intelligent electronic devices (IEDs), which is substation systems lifeblood and the system availability is decided by its real-Time performance. International Electro-Technical Commission (IEC) has been developed the standards based on object-oriented technologies for substation automation. IEC 61850 protocol has been applied widely in substation communication applications. It presents new challenges to realtime performance simulation and testing of protective relays. In this paper, an optimized network engineering tool (OPNET) or Riverbed modeler simulation tool/ software has been used for the modeling of IED in substation level network. Based on the simulation results, different types of data stream have been discussed, such as, periodic data stream, random data stream and burst data steam. The typical studies using these models, to construct substation automation system (SAS) network on the OPNET modeler or Riverbed modeler was made to reveal the impact of each affecting parameter or factor to the real-Time performance of substation communications system, which is also incorporated in this report.
Description:
2015 Australasian Universities Power Engineering Conference: Challenges for Future Grids, AUPEC 2015
Description:
IEC 61850 Standard was introduced to address the challenge presented by existence of the multiple protocols in substation communications, which include many proprietary protocols; and to address the challenge introduced by legacy complicated substation from both cost and complicity. In this paper, the simulation results of different types of IEC 61850 network system configurations using OPNET Modeler simulation software were presented and the influence on data rate and delay characteristics of these system configurations were evaluated. The simulated results confirm that the ring configured system suitable for higher loading characteristics and higher system reliability.
Description:
Subwavelength grating (SWG) structures make an excellent alternative antireflective (AR) coating due to its capacity to reduce the reflection losses in GaAs solar cells. The SWG structures allow the gradual change in refractive index that confirms an excellent AR coating and the light trapping properties when compare with planar thin film structures. Finite-difference time domain (FDTD) method is used to simulate the reflection losses of the SWG structure in GaAs solar cells. The FDTD simulation results show that the slightly change of incident angle affect the reflection losses of all nano-grating structure. The simulation results also confirmed that the reflection loss of nano-grating structure maintained optimum within ~±5° of incident angle tolerance for the grating height over 300-nm for minimizing the reflection losses in GaAs solar cells.
Description:
Interoperability among multi-vendor substations automation devices, is now achievable due to the introduction of IEC 61850 standard, which allows power system communication between substations. This standard does not mandatorily demands for redundancy in any type of substation neither does it mentions a specific type of substation design application. Ethernet based communication protocols for substation automation systems (SASs) are specified in IEC 61850 standard. The standards include Ethernet based process-level connections between switchyards and control rooms. However, their in-service performance is not well known. Moreover, IEC 61850 demands for a communication topology which is zero point failure proof and provides worthy data transmission rates, without pursuing any delays. In order to achieve these norms, Ethernet architectures must be modelled and analysed in detail. The performance of individual architecture must be analysed in terms of their reliability, availability and efficiency of data transfer. This paper presents the reliability and availability using the reliability block diagrams, along with OPNET network real-time simulations, which shows the efficiency of individual architecture along with comparing and synthesizing the most effective communication topology for the SASs.
Description:
The finite-difference time domain (FDTD) tool is used to simulate the reflection losses of subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures act as an excellent alternative antireflective (AR) coating due to its capacity to reduce the reflection losses in GaAs solar cells. The SWG structures allow the gradual change in refractive index that confirms an excellent AR coating and light trapping properties, when compared with the planar thin film structures. The nanorod (nano-grating) structure acts as a single layer AR coating, whereas the triangular (conical or perfect cone) and parabolic (i.e., trapezoidal or truncated cone) shaped nano-grating structures act as a multilayer AR coating. The simulation results show that the reflection loss of triangular (conical or perfect cone) shaped nano-grating structure having a 300 nm grating height and an 830 nm period is ~2 %, which is about 28 % less than that of flat type substrates. The simulated results show that the light reflection of a rectangular shaped grating structure is ~30 %, however, the light reflection becomes ~2 % for a triangular (conical or perfect cone) shaped nano-grating structure, because the refractive index changes gradually in several steps and reduces the reflection losses. It is also noticed that the intermediate structures (trapezoidal and parabolic shaped), the light reflection loss is lower than the rectangular shaped nano-grating structure but higher than the triangular shaped nano-grating structure. The simulated results confirm that the reduction of light reflection losses in GaAs solar cell will increase the conversion efficiency. Therefore, this analysis confirmed that the triangular (i.e., perfect cone or conical) shaped nano-grating structures are an excellent alternative AR coating for the improvement of conversion efficiency in GaAs solar cells.
Description:
This paper presents the design and analysis of nano-structured gratings to improve the conversion efficiency in GaAs solar cells by reducing the light reflection losses. A finite-difference time domain (FDTD) simulation tool is used to design and simulate the light reflection losses of the subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures perform as an excellent alternative antireflective (AR) coating due to their capacity to reduce the reflection losses in GaAs solar cells. It allows the gradual change in the refractive index that confirms an excellent AR and the light trapping properties, when compared with the planar thin film structures. The nano-rod structure performs as a single layer AR coating, whereas the triangular (i.e., conical or perfect cone) and parabolic (i.e., trapezoidal/truncated cone) shaped nano-grating structures perform as a multilayer AR coating. The simulation results confirm that the reflection loss of triangular-shaped nano-grating structures having a 300-nm grating height and a 830-nm period is about 2%, which is about 28% less than the flat type substrates. It also found that the intermediate (i.e., trapezoidal and parabolic)-shaped structures, the light reflection loss is lower than the rectangular shaped nano-grating structure, but higher than the triangular shaped nano-grating structure. This analysis confirmed that the triangular shaped nano-gratings are an excellent alternative AR coating for conversion efficiency improvement in GaAs solar cells.
Description:
This paper presents the design and analysis of nano-structured gratings to improve the conversion efficiency in GaAs solar cells by reducing the light reflection losses. A finite-difference time domain (FDTD) simulation tool is used to design and simulate the light reflection losses of the subwavelength grating (SWG) structure in GaAs solar cells. The SWG structures perform as an excellent alternative antireflective (AR) coating due to their capacity to reduce the reflection losses in GaAs solar cells. It allows the gradual change in the refractive index that confirms an excellent AR and the light trapping properties, when compared with the planar thin film structures. The nano-rod structure performs as a single layer AR coating, whereas the triangular (i.e., conical or perfect cone) and parabolic (i.e., trapezoidal/truncated cone) shaped nano-grating structures perform as a multilayer AR coating. The simulation results confirm that the reflection loss of triangular-shaped nano-grating structures having a 300-nm grating height and a 830-nm period is about 2%, which is about 28% less than the flat type substrates. It also found that the intermediate (i.e., trapezoidal and parabolic)-shaped structures, the light reflection loss is lower than the rectangular shaped nano-grating structure, but higher than the triangular shaped nano-grating structure. This analysis confirmed that the triangular shaped nano-gratings are an excellent alternative AR coating for conversion efficiency improvement in GaAs solar cells.
Description:
Spectroscopic analysis is recently being employed to measure furan concentration in transformer oil. Light absorbance and spectral bandwidth are used as indicators to estimate furan concentration level in transformer oil. However, the possibility of dust and other conducting materials that might exist in transformer oil sample need to be considered as it may influence the spectroscopic performance. In this paper, series of tests are carried out to investigate the impact of dust on the transformer oil spectral response characteristics. Oil sample with various furan concentrations along with certain amount of copper powder are examined. Experimental results show that the spectral response characteristics only affected by dust at the beginning of mix process. However, the characteristic returns to the original one within a few minutes.
Description:
High speed communication is critical in a digital substation from protection, control and automation perspectives. Although International Electro-Technical Commission (IEC) 61850 standard has proven to be a reliable guide for the substation automation and communication systems, yet it has few shortcomings in offering redundancies in the protection architecture, which has been addressed better in IEC 62439-3 standard encompassing Parallel Redundancy Protocol (PRP) and High-Availability Seamless Redundancy (HSR). Due to single port failure, data losses and interoperability issues related to multi-vendor equipment, IEC working committee had to look beyond IEC 61850 standard. The enhanced features in a Doubly Attached Node components based on IEC 62439-3 provides redundancy in protection having two active frames circulating data packets in the ring. These frames send out copies in the ring and should one of the frame is lost, the other copy manages to reach the destination node via an alternate path, ensuring flawless data transfer at a significant faster speed using multi-vendor equipment and fault resilient circuits. The PRP and HSR topologies provides higher performance in a digitally protected substation and promise better future over the IEC 61850 standard due to its faster processing capabilities, increased availability and minimum delay in data packet transfer and wireless communication in the network. This paper exhibits the performance of PRP and HSR topologies focusing on the redundancy achievement within the network and at the end nodes of a station bus ring architecture, based on IEC 62439-3.
Description:
High speed communication is critical in a digital substation from protection, control and automation perspectives. Although International Electro-Technical Commission (IEC) 61850 standard has proven to be a reliable guide for the substation automation and communication systems, yet it has few shortcomings in offering redundancies in the protection architecture, which has been addressed better in IEC 62439-3 standard encompassing Parallel Redundancy Protocol (PRP) and High-Availability Seamless Redundancy (HSR). Due to single port failure, data losses and interoperability issues related to multi-vendor equipment, IEC working committee had to look beyond IEC 61850 standard. The enhanced features in a Doubly Attached Node components based on IEC 62439-3 provides redundancy in protection having two active frames circulating data packets in the ring. These frames send out copies in the ring and should one of the frame is lost, the other copy manages to reach the destination node via an alternate path, ensuring flawless data transfer at a significant faster speed using multi-vendor equipment and fault resilient circuits. The PRP and HSR topologies provides higher performance in a digitally protected substation and promise better future over the IEC 61850 standard due to its faster processing capabilities, increased availability and minimum delay in data packet transfer and wireless communication in the network. This paper exhibits the performance of PRP and HSR topologies focusing on the redundancy achievement within the network and at the end nodes of a station bus ring architecture, based on IEC 62439-3.
Description:
Digital Communication is the future of High Voltage (HV) substation automation, protection and control. It not only offer ease of diagnostics but acts fast to isolate healthy feeders from faulty ones. The effect of this digital protection technology is being appreciated by many utilities and industries for the benefit it offers to them and looks to be the future. Some of the utilities are replacing their secondary copper wires with Fibre Optics (FO) and Ethernet wires as they want load the cable trays less and identify the FO better than the secondary copper wires. Conventional relays are being replaced with Intelligent Electronic Devices (IEDs) during asset management replacement program. Switchyard equipment such as instrument transformers filled with oil and SF6 gas are being replaced with Non-Conventional Instrument Transformer (NCITs). Ushering new devices into the network are not without challenges. These devices and peripherals cannot be put into use by the end user without proper assessment and needs to be validated with number of tests for its performances. To get end users acceptance, laboratory and field tests are carried out to study the propagation delays and performance issues as applicable to digital automation and protection scheme. This paper discusses an early detection of the loss of data packets in a star connected Ethernet Substation Automation Systems (SAS). Understanding a real model in a lab environment is an important step towards performance evaluation and identification of issues. With the involvement of multiple manufacturer in the digital substation, it is good to set a trial of the interoperability of equipment involving their products which could address critical protection issues. This paper focuses on a star connected architecture using an Optimized Network Engineering Tool (OPNET) lab-based software simulating the latency and delays of a digital protection scheme in a 132/22-kV zone substation.
Description:
Power transformer is an important asset within the electrical power system network. Frequency Response Analysis (FRA) has been developing in popularity in recent years as a tool to detect mechanical deformation of power transformers winding. Since the FRA has been relying on graphical analysis, it calls for an expert person to analyze the results to detect the type of the fault and its location. There are no reliable guidelines for FRA signature in the event that a failure occurs in service and the impact can be far reaching. The concept of FRA has been successfully used as a diagnostic technique to detect the winding deformation, core and clamping structure for the power transformers. This paper investigated the impact of the forced and free winding buckling based on the variation of the electrical parameters to show how these faults vary the FRA signature.
Description:
This paper investigates the impact of conducting materials on the correlation of furan concentration in transformer oil and its spectral response characteristics. The presence of furan derivatives in aged-transformer oil has been one of the key indicators for solid dielectric deterioration. Identification and quantification of furan derivatives are currently performed using high performance liquid chromatography or gas chromatography-mass spectrometry based on ASTM D5837 standard. Although these techniques are well established, they need an expert personal to conduct the test and to analyse its results. Moreover, the test is relatively expensive and the analysis of oil sample may take days as most utilities sending transformer oil samples to external laboratories to be tested. Recently, it has been proven that furan concentration in transformer oil has a strong correlation to the oil spectral response. This paper is to validate this finding and to investigate the impact of conducting materials within transformer oil on this correlation. In this context, extensive experimental tests are conducted to assess the impact of various concentration of conducting materials (e.g., copper dust) dissolved in transformer oil samples of different furan contents on its absorption and transmission spectra. The measured experimental results show that, the impact of such small amount ofdissolved conducting materials on the oil spectral response is minimal.
Description:
High speed communication is an essential feature of Substation Automation and Control. Existing International Electro-technical Commission (IEC) 61850 guidelines substation automation and communication systems have few shortcomings in the protection architecture which necessitated an upgrade to another guideline. This has been addressed better in IEC 62439-3 standard encompassing Parallel Redundancy Protocol (PRP) and High-availability Seamless Redundancy (HSR), Earlier there have been number of issues with IEC 61850, due to single port failure, data losses and interoperability related to multi-vendor equipment. The enhanced features of a Double Attached Node component based on IEC 62439-3, provide redundancy in protection by virtue of having two active frames circulating in the ring. These frames send out copies in the ring. Should one of them be lost, the destination node will receive alternate frame, ensuring flawless data transfer at a significant faster speed in a multi-vendor equipment ensuring the circuit is fault resilient. PRP and HSR topologies promise enhanced reliability over IEC 61850 standard due to faster processing capabilities, increased availability in the scheme with least delay time in circulating data packet in wireless communication in the network. This paper exhibit performance of PRP and HSR topologies addressing redundancy within the network ring leveraging on IEC 62439-3.
Description:
This paper investigates the communication network architectures for power systems between substations using IEC 61850. Optimized Network Engineering Tools (OPNET) is used for the simulations. The simulation results show the performance of individual architectures power system communications (PSC) for substation automation systems (SASs). Nowadays, interoperability among multi-vendor substations automation devices is achievable using IEC 61850 standard which allows the PSC between substations. Ethernet based communication protocols for the SASs are specified in IEC 61850 standard. These standards include Ethernet based process-level connections between switchyards and control rooms. However, their in-service performance is not well known yet. The IEC 61850 demands for a communication topology which is zero point failure proof and provides worthy data transmission rates, without pursuing any delays. In order to achieve these norms, Ethernet architectures are modeled and analyzed in detail. The performance of individual architecture also analyzed in terms of their reliability, availability and efficiency of data transfer. The hybrid, star-ring and redundant ring network architectures are the most efficient in terms of data transmission, delay times, reliability and availability between the SASs for data transmission.
Description:
Intelligent Electronic Devices (IEDs) diagnose faults and traffic issues of data packets in a reliable and efficient manner in a substation environment. These devices determine abnormal system condition, wide area disturbances offering greater flexibility to the operator in terms of condition monitoring and diagnostics. In a distribution system, end user get multiple faults in the network and one such nuisance disruption of power on a faulty feeder results in sympathetic tripping. Sympathetic tripping occurs during high load conditions causing entire protection system to spuriously trip due to an out of section fault. Occurrence of such faults could be attributed to load unbalance in the distribution feeders, delayed voltage recovery conditions, voltage swell/sag in the feeders etc. Usually, this phenomenon occur when loads containing low inertia rotating equipment are connected to distribution feeders. In this paper, an Optimized Network Engineering Tool (OPNET) is used to simulate, mitigate faults attributed to Sympathetic Tripping in a laboratory environment.
Description:
This paper focuses on modeling of multi-junction solar cell (MJSC) to improve the conversion efficiency using MATLAB/Simulink software. The multi-junction photovoltaic (PV) cell is investigated to obtain its maximum performance compare to the conventional silicon PV cell. MATLAB/Simulink modeled results show that tandem cell can provide almost 3-times maximum power compared to the conventional PV cells. Maximum power point tracker (MPPT) has also been performed to improve the conversion efficiency of the PV systems. The MPPT is able to assist the PV cells to attain more power efficiently and deliver electricity to the grid.
Description:
This paper presents modelling and analysis of multi-junction solar cells to improve the conversion efficiency of photovoltaic (PV) power generation systems. For this modelling, Matlab/Simulink tool is used to obtain the simulation results. The modelling of a single junction solar cell can be performed by single or double diode models. From the simulation results, it was found that the double diode model is more accurate than the single diode model. Hence, the double diode model is used to simulate dual and triple junction solar cells. The simulations were performed under varying the critical factors, such as temperature and solar irradiance. The effect of these factors was clearly demonstrated on the I-V and P-V characteristics of the solar cells. It was found that the temperature increases, short circuit current increases slightly and open circuit voltage drops significantly. Consequently, the PV power generation decreases considerably. However, when the irradiance increases, the short circuit current increases slightly and the open circuit voltage increases significantly. Consequently, the power generation increases considerably and the conversion efficiency increases of the PV systems.