Power Plant Protection Research Articles

Experimental study on the application of nanofiltration concentrated water in the preparation of burning-free bricks

ABSTRACT The realization of zero discharge of desulfurization wastewater has become a major trend in the environmental protection of power plants. After the desulfurization wastewater is treated by the nanofiltration process, a certain amount of nanofiltration concentrated water will be produced. Based on the water quality and quantity analysis of nanofiltration concentrate, this study proposes to apply nanofiltration concentrate to the preparation of free-sintering brick to realize the resource utilization of nanofiltration concentrate. The results show that the optimal ratio of the cement-to slag ratio ratio is 1:0.8, the 28d strength of the solidified body is 18.64MPa, the water absorption rate is 15.9%, and the water-soluble chloride ion content is 4.8%. In order to further optimize the production technology to improve the performance of the curing body, the later experiments optimized the curing formulation with the water-reducing agent sodium lignosulfonate as an admixture and obtained the optimal addition ratio of sodium lignosulfonate which was 0.2%. Finally, an economic evaluation was conducted and the use of nanofiltration concentrate for the preparation of free sintering brick could bring considerable economic benefits to the power plant while achieving the purpose of reducing environmental pollution and reducing the investment cost of environmental management.

Testing and Evaluation of Wind Power Plant Protection System

This paper discusses methodology and test set up which may be used for Wind Power Plant (WPP) planning and protection system evaluation. The test set up consists of a digital simulator, as well as a number of physical relays, recorders, software for system and relay modeling, signal editing, etc. Minimizing economic loss, in terms of using maximum output of wind generated power without interruption and causing minimum equipment damage due to faults, is the main benefit of having protection system that operates correctly. The correctness of operation is crucial during grid disturbances in preventing unwanted power plant disconnection and further system stability violation. Since there are no standardized requirements or methodology for WPP protection system testing, its evaluation is challenging and manly customized to fit a given solution. This paper discusses test requirements and test methodology to perform the evaluation in a comprehensive manner.

OPTIMIZING POROUS MATERIALS WITH PREDICTION THERMAL PHYSICAL CHARACTERISTICS

The article presents experimental data, based on which the influence of various factors on the strength and thermophysical characteristics of porous heat-insulating materials was studied.
 Porous bodies in thermal power engineering are used for thermal protection of power plants, various aggregates, in thermal insulation structures of buildings and technological networks. The properties of these materials and the field of use depend on their chemical composition and method of production.
 The task of this research is to obtain a raw material mixture for heat-insulating material of the closed-cell type with increased thermal resistance and porosity by optimizing its qualitative and quantitative composition. The goal is also to improve the method of obtaining porous heat-insulating material by changing the temperature and time regimes in order to improve the physical, mechanical and operational characteristics, which will allow the material to be used in a wider temperature range.
 Based on the dependences of strength and thermophysical properties on the density of the finished material obtained in the work, it was concluded that the best characteristics are the samples of the porous material with the lowest density, which are formed at the maximum humidity of the raw material. Kinetics of drying and heat treatment of the raw material mixture, thermal regimes are the main factors that determine the porosity, strength and thermal conductivity of the finished heat-insulating material.
 Performed laboratory studies of the material proposed in the paper allow choosing the required temperature regimes of heat treatment. Thus, the task of further research is to choose a method of organizing effective heat and mass exchange, modeling these processes, experimental testing of the obtained data, and creating a method for determining the main technological and structural parameters of the method of obtaining a new material.
 The performed experimental studies made it possible to determine the conditions for the implementation of new technologies for the production of porous materials with the possibility of predictive determination of their properties.

Intelligent Expert System for Diagnosing Faults and Assessing Quality of Power Transformer Insulation Oil by DGA Method

Accurate assessment of oil and fault diagnostics of electrical power transformer insulation for lifelong endurance are the key issues addressed in this research. The durability of a transformer is significantly determined by the quality of its insulation oil, which deteriorates over time due to temperature fluctuations and moisture content. Protecting transformers from potential failure through the early and precise diagnosis of faults and efficient assessment of oil quality during the actual conduct of the operation can avoid sizeable economic losses. The ANFIS Expert System that uses intelligent software plays an important role. The dissolved gas analysis (DGA) in oil is reliable for diagnosing faults and assessing insulation oil quality in transformers. Transformer power plant protection teams often suffer sudden breakdowns that lead to massive damage and huge financial losses. The oil in transformers must be appropriately treated to circumvent such failures. In this research, an ANFIS Expert System was used to diagnose faults and assess insulation oil status and quality in power transformers. by the Rogers ratio method depending on the DGA in oil, a suitable treatment was identified. The graphical user interface from the MATLAB environment was used and proven effective for fault diagnosis and oil quality evaluation. The training algorithm can assess oil quality according to the specifications of the IEEE standard C57-104 and the IEC standard 60599.

Theory behind the Zone Concept for External Lightning Protection of Photovoltaic Power Plants

The current practice of creating the external lightning protection system for photovoltaic power plants, according to the IEC 62305 standard series, is overly generalised. The common problems with the usage of the standard are also presented. A novel method is demonstrated to address them, which is called zone concept. It creates the opportunity to optimise the external lightning protection system better and decide the appropriate lightning protection level, if required. It can be achieved by considering the real layout of the power station and highlighting zones of interest inside it. The application process of the zone concept is demonstrated generally, and calculations are also carried out for a specific photovoltaic power station. The concrete example showed that the difference could be significant financially, but the effectiveness of external lightning protection system is not lowered notably if lowered at all with the zone concept compared to the standardised procedure. Since the calculation is parametric, the equivalent area value can be obtained in any climatic zone with the appropriate lightning parameters and using the proper isokeraunic lightning density value. The general form of the zone concept presented in this paper could be used in the standard for photovoltaic power plants specifically.

Five-Year Performance of an ESE Lightning Protection System for a Large Scale PV Power Plant in Thailand

This article presents a five-year performance review of an early streamer emission (ESE) air terminal lightning protection system for a large scale PV power plant in Thailand. The comparison effect of a Franklin lightning protection system and the ESE lightning protection system was analyzed for the PV power plant. The ESE lightning protection system was selected to be implemented in the PV power plant. The capacity of the PV power plant studied was 8 MWp on an area of 150,000 square meters in the Nong Ya Plong district, Phetchaburi province, Western Thailand. A Franklin lightning rod type was also designed to be implemented in this PV power plant. The Franklin lightning rod type comprised 122 pieces but the ESE lightning rod type consisted of only 11 pieces. The conceptual design of the Franklin rod type followed the standard of the Council of Engineers, Thailand, and the ESE lightning rod type followed the NFC17102 standard of France. The estimated cost of installation was a key comparison to select the lightning protection system; the total installation cost of the Franklin lightning rod type was USD 197,363.80 and the ESE lightning rod type was USD 44,338.06. The lightning system was applied to the lightning arrester in the power plant to provide good protection, in which the balance of the pole to the mounting position is required to optimize the system performance. The result of the simulation also showed that the shading effects of the Franklin rod type were greater than the ESE rod type. The installation cost of the Franklin lightning rod type was 4.45 times more expensive than the ESE lightning rod type. Therefore, the ESE lightning protection system was selected to be implemented in the PV power plant. From the recorded data of the five-year performance of the ESE lightning protection system (2016–2020), there were three occurrences of a lightning strike on the PV power plant. The ESE lightning protection system effectively protected and prevented the lightning strike to the PV power plant. This study can help and support with the selection of a lightning system for the protection of large scale PV power plants in the future.

Lightning Protection of High-performance Photovoltaic Power Plants: Issues of Parts to Be Covered by the Lightning Protection System

This paper aims to represent when the primary lightning protection is not necessary for a photovoltaic power plant with a special dimension if the different security objects are not negligible during the probability and risk calculations. The calculations were made using the Probability Modulated Attractive Volume theory which is capable of special, complicated, or huge structures and objects like a high-performance photovoltaic park.

Fault Tolerant Control Algorithm of Hexarotor UAV

As the best representative of the current cutting-edge technology, unmanned aerial vehicle (UAV) is widely used in various fields such as electric power inspection, agriculture, forestry and plant protection, fire rescue, and film and television shooting. With the rapid development of UAV, the safety work of UAV has become more important. In order to improve the safety of hexarotor UAV during flight, a fault-tolerant control scheme independent of basic control law and control distribution is designed in this paper. Firstly, the linear active disturbance rejection control (LADRC) was used as the basic control law for attitude control of hexarotor UAV. Secondly, in the case of actuator failure of hexarotor UAV, a fault observer was used to estimate fault information accurately. Then, on this basis, the control distribution matrix was adjusted to reduce the use of the faulty motor, and the purpose of fault-tolerant control was achieved. Finally, simulation experiments and actual flight experiments were carried out to verify the effectiveness of the proposed scheme. Experimental results show that the proposed scheme can improve the robustness of the control system and the flight safety of UAV.

Genetic Algorithm-Based Optimization of Overcurrent Relay Coordination for Improved Protection of DFIG Operated Wind Farms

Rigorous protection of wind power plants is a critical aspect of the electrical power protection engineering. A proper protection scheme must be planned thoroughly while designing the wind plants to provide safeguarding for the power components in case of fault occurrence. One of the conventional protection apparatus is overcurrent relay (OCR), which is responsible for protecting power systems from impending faults. However, the operation time of OCRs is relatively long and accurate coordination between these relays is convoluted. Moreover, when a fault occurs in wind farm-based power system, several OCRs operate instead of a designated relay to that particular fault location, which could result in unnecessary power loss and disconnection of healthy feeders out of the plant. Therefore, this article proposes a novel genetic algorithm (GA)-based optimization technique for proper coordination of the OCRs in order to provide improved protection of the wind farms. The GA optimization technique has several advantages over other intelligent algorithms, such as high accuracy, fast response, and most importantly, it is capable of achieving optimal solutions considering nonlinear characteristics of OCRs. In this article, the improvement in protection of wind farm is achieved through optimizing the relay settings, reducing their operation time, time setting multiplier of each relay, improving the coordination between relays after implementation of IEC 60255-151:2009 standard. The developed algorithm is tested in simulation for a wind farm model under various fault conditions at random buses and the results are compared with the conventional nonlinear optimization method. It is found that the new approach achieves significant improvement in the operation of OCRs for the wind farm and drastically reduces the accumulative operation time of the relays.

Model-Checking Detailed Fault-Tolerant Nuclear Power Plant Safety Functions

Model checking has been successfully used for detailed formal verification of instrumentation and control (I&C) systems, as long as the focus has been on the application logic alone. In safety-critical applications, fault tolerance is also an important aspect, but introducing I&C hardware failure modes to the formal models comes at a significant computational cost. Previous attempts have led to state space explosion and prohibitively long processing times. In this paper, we present an approach to model and formally verify protection functions allocated to one or several I&C systems, accounting for hardware component failures and delays in communication within and between the systems. Formal verification is done with model checking, whose feasibility on such complex systems is achieved by utilizing the symmetry of I&C systems: the components of the overall model that do not influence the checked requirements are eliminated, and the failing components are fixed. Generation of such abstracted models, as well as subsequent verification of their requirements and symmetry with the NuSMV symbolic model checker, is handled by a software tool. In addition, we explore how to specify formal requirements for systems of the considered class. Based on a case study built around a semi-fictitious nuclear power plant protection system that achieves reliability by means of redundancy, we demonstrate how failure tolerance of even detailed system designs can be formally verified.

Novel grid connection interface for utility‐scale PV power plants based on MMC

The ever-increasing integration of photovoltaic (PV) energy has led to the fast development of utility-scale PV power plants worldwide. A novel grid connection interface for utility-scale PV power plants based on the modular multi-level converter (MMC) is explored. The grid connection interface is a DC boost interface by nature. It adopts the multistring topology, employs DC/DC boost converters, utilises a centralised MMC, and integrates an energy storage system. Meanwhile, the two-level control system for the DC boost interface is also designed. Compared with the conventional AC boost interfaces, the proposed DC boost interface avoids problems regarding reactive power transmission, harmonic resonance, and synchronous stabilisation. It also improves the power quality, efficiency, and the integration capacity of the PV generation. A case study of a utility-scale PV power plant with the DC boost interface is carried out in PSCAD/EMTDC. The simulation results validate the effectiveness and the merits of the DC boost interface under different operation conditions. The proposed DC boost interface proves more suitable for utility-scale PV power plants in areas with high solar irradiance. It also lays a solid foundation for the future research regarding the control and protection of utility-scale PV power plants.

Fine classification of construction land using high-resolution remote sensing images: a case study in planning restricted zone of nuclear power plant

Detailed construction land information plays a significant role in monitoring planning restricted zone of nuclear power plant and ecological environment protection. This study focuses on developing fine classifying method of construction land in planning restricted zone of nuclear power plant using high spatial resolution GF(GaoFen)-1 remote sensing images. The object-oriented classification method is used in this study; the important process of which is image segmentation and classification. Multi-scale segmentation method, rule-based decision tree, and the nearest neighbor classifier are used in classifying construction land classes, i.e., road, industrial, and residential. An optimal segmentation scale is crucial to image segmentation in object-oriented classification. Instead of laborious trial-and-error experiments for optimal image segmentation, the change rates of the local variance in the homogeneous region are calculated to get the optimal segmentation scales. Multi-level classification strategy is used in the following classification. Rule-based decision tree is used to classify road and water, vegetation and non-vegetation, and industrial and residential. And the nearest neighbor classifier is used to classify cropland and forest within the vegetation land use type. The accuracy assessment result shows that the overall accuracy is 89.67% and Kappa coefficient is 0.85 for object-oriented classification, which is much higher than pixel-based maximum likelihood classifier (overall accuracy is 79.17% and Kappa coefficient is 0.74) and support vector machine classifier (overall accuracy is 74.16% and Kappa coefficient is 0.68).

Performance Verification of Distance Relaying and Modeling of Hydroelectric Generator Control System using PSCAD Software

Considering the influence on the operation and power supply of a power system, generator protection is extremely vital. Highly reliable integrated relays or IEDs for generator fault protection are required. While most of power plant protection relays in Korea have been dependent on advanced foreign technologies, the demand for the modernization and localization of switchgear is growing. Recently, the KHNP(Korea Hydro and Nuclear Power) has been conducting a localization development project of generator protection relays and generator digital simulator.BR In this paper, the hydroelectric generator control system of △△△ Power Plant was modeled and distance relaying was simulated using PSCAD software for a protection plan of generator IED design. Through the simulation, a short fault that may occur in the generator was analyzed and the performance of distance relaying was verified.

발전소 보호를 위한 IED 시뮬레이터 설계에 관한 연구

발전소 보호를 위한 IED 시뮬레이터 설계에 관한 연구

A Phase Selection Method for Wind Power Integration System Using Phase Voltage Waveform Correlation

The fault characteristics of the wind power system, which are reflected in the weak feed features, variation of system impedance, frequency deviation, and non-sinusoidal waveform, will cause the inadaptation of traditional phase selectors to a wind power integration system. In this paper, a new phase selection principle based on the waveform correlation of transient voltage is proposed, which is valid for relay protection of intermittent solar or wind power plants. First, the characteristics of transient voltage of various fault types are deduced according to their boundary conditions. And on this basis, the correlations between the fault transient voltages of every two phases can be acquired. With the differentiated waveform correlations of different fault types, the fault phase selection criterion based on correlation coefficient is formed accordingly. Because it depends on the waveform characteristics of fault transient voltages, the new phase selector is not influenced by the wind power system's fault characteristics and it can select the correct fault phase quickly with high sensitivity. The proposed novel phase selection criterion is verified by the PSCAD-based simulation results and field fault recording data of the wind power integration system.

The cost of electric power generation in Guangdong Province

ABSTRACTThe typical thermal power plant, nuclear power plant, hydropower plant, liquefied natural gas power plant, wind power plant, and biomass power plant in Guangdong province were selected as the research objective in the present study. The corrected calculation model was utilized to study the total cost of electric power generation (COE) for various power plants. The results show that the competitiveness on the environmental protection of thermal power plants is the weakest because the cost of environment reaches 62.810 yuan/MWh, which is much higher than those of other types of power plants. The total COE of hydropower plant was the lowest at 256.011 yuan/MWh. The total cost of biomass power plant is the highest one, which arrives at 668.865 yuan/MWh.

Calculations for AP1000 nuclear power plant SGTR accident based on RELAP5/mod 3.3 program

AP1000 nuclear power plant model is founded via RELAP5/mod 3.3 program in detail. Refer to SGTR accident basic assumptions in the safety analysis report, calculations for AP1000 nuclear power plant SGTR accident are carried out. And through comparison between the result got and the result from safety analysis report calculated by LOFTTR2 program, the two results are very consistent. It's found that even if the operators do not interfere, AP1000 nuclear power plant protection systems and passive design measures will trigger an automatic response measures, it can terminate the SG heat transfer tube leaking and make RCS be stable in a safe condition and to prevent SG overflowing and ADS actions occurring.

Wartime Nuclear Power Plant Security Protection Research

Nuclear power as an important energy which benefits human being,is being more and more widely used in many countries all over the world. Under the condition of information war, threat to nuclear power plant security from precision weapon and terrorist attack is serious. This paper analyzes major threats nuclear power plant be facing to in wartime such as obvious exposure symptoms, limited own protections and large impact on the war potential. Then several main methods are discussed to strengthen safety protection of nuclear power plant. Firstly, strive to improve the early warning ability of nuclear power plant. By this means, more time can be obtained to make nuclear power plant protection to prepare. Secondly, counterattacks, interference and disguise simultaneously should build another effective barrier. In the last, it is considered that research on protection and rescue of nuclear power station should be strengthened also.

20 kHz 전력설비 접지시스템 분석에 관한 연구

In this paper, carried out for optimal ground system for ensuring safety for electricity used to power equipment in the 20 kHz frequency. Now the grounding system of the mesh electrode, electrode rods are installed for power plant safety and protection against electric shock. However, the electrical equipment grounding system in the 20 kHz were considering the increasing grounding impedance due to the high frequency and the magnetic shielding. But until now, there has been little research on the grounding system. To solve this problem, In this paper was proposed optimal grounding system due to the experiment using a mesh electrode, rod electrode, aluminum plate electrodes. Measurement results, grounding resistance was depending on the material of the electrode grounding resistance. In addition, the leakage current (induced) appeared to be affected depending on the type of electrode.

Estimation of lightning vulnerability points on wind power plants using the rolling sphere method

The escalating number of wind power plants in many countries makes their reliability and safety of crucial importance. One of the main causes of damages for wind power plants is constituted by lightning. Hence, appropriate tools for the lightning protection of wind power plants are required. We have developed a new computer program in Visual Basic, LPS 2008, which runs over AutoCAD and is able to perform risk assessment on a structure or on a service due to lightning flashes to ground. Computer simulations obtained by using LPS 2008 are presented, and conclusions are duly drawn.