Study on Lightning Protection Design of DCS in a Nuclear Power Plant

DCS （distributed control system） plays a decisive role in the overall operation of a nuclear power plant. If DCS fails, it will seriously affect the normal production of nuclear power plant, causing great losses. So it is very important to take perfect lightning protection measures on DCS of the nuclear power plant. In this paper, according to the actual situation of DCS in a nuclear power plant, by controlling lightning point, securely booting lightning into the ground network, improving low-resistance ground network, eliminating ground loops, determining the safety space, surge protection of power and signal, a set of complete lightning protection design scheme was systematically put forward. Some specific lightning protection measures were highlighted, such as the DCS grounding, equipotential bonds and shields, and some specific considerations were put forward. All of these could offer reference in the practical application.

Operation Control Method of Relay Protection in Flexible DC Distribution Network Compatible with Distributed Power Supply

A novel operation control method for relay protection in flexible DC distribution networks with distributed power supply is proposed to address the issue of inaccurate fault location during relay protection,leading to poor performance.The method combines a fault-tolerant fault location method based on long-term and short-term memory networks to accurately locate the fault section.Then,an operation control method for relay protection based on adaptive weight and whale optimization algorithm(WOA)is used to construct an objective function considering the shortest relay protection action time and the smallest impulse current.The adaptive weight and WOA are employed to obtain the optimal strategy for relay protection operation control,reducing the action time and impulse current.Experimental results demonstrate the effectiveness of the proposed method in accurately locating faults and improving relay protection performance.The longest operation time is reduced by 4.7023 s,and the maximum impulse current is limited to 0.3 A,effectively controlling the impact of large impulse currents and enhancing control efficiency.

Reactor Protection Diversity Requirements and the Typical Solution Based on DCS

The defense-in-depth and diversity have become the basic requirements for digital I＆C and should be strictly followed when carrying out the overall scheme design of digital control system, in which the risk of common cause failure has to be prevented or coped with. This paper analyzes the requirements of the diversity principle and sums up the typical solution of the diversified protection of reactor based on the CPR1000 NPP. Some concepts will be helpful to the design of DCS for others plants.

Appropriate Attitude and Principle for Strengthening Human Rights Protection——Speech at the opening ceremony of the 12th Sino-German Human Rights Symposium, July 13, 2014

Since 1999, there have been 11 Sino-German Human Rights symposiums. Due to the concept of peace and development and the principle of dialogue through consultation, non- confrontation and pragmatism with equality, which have been upheld by organizers, such symposiums have made great achievements. The dialogue mechanism for human rights topics between China and Germany has helped construct a common, accessible and interactive platform for pushing forward human rights legal advancement in both countries, which has brought about a positive influence on the develop- ment of the human rights cause in the two countries. Strengthening legal construction and ensuring hu- man rights are not only the shared aspiration of all the people in the world, but also the irreversible his- torical trend of human civilization. The symposium, with the theme of international law and human rights protection, encourages participants to discuss and share theories and practices in human rights studies, which makes a significant contribu- tion to enriching the modern human rights concept and building a new type of international cooperation. The international community always pays great attention to the relation- ship between human rights and legal governance. China always abides by international human rights con- ventions including the Universal Declaration of Human Rights, which set up fundamental principles for promoting and ensuring human rights, and has endorsed 26 inter- national human rights conventions such as the International Covenant on Economic, Social and Cultural Rights. Meanwhile, China, through legislation, jurisdiction and admin- istration, brings into full play the active role of international human rights conventions in ensuring hu- man rights in the country.

A Single-Ended Protection Principle for LCC-VSC-MTDC System with High Resistance Fault Tolerance

Line-commutated converter-voltage source converter(LCC-VSC)power transmission technology does not have the problem of communication failure very usually.It therefore can support the long-distance,long-capacity transmission of electric energy.However,factors such as topology,control strategy,and short-circuit capacities make the traditional protection principles not fully applicable to LCC-VSC hybrid transmission systems.To enhance the reliability of hybrid DC systems,a single-ended principle based on transmission coefficients is proposed and produced.First,the equivalent circuit of the LCC-VSC hybrid DC system is analyzed and the expression of the first traveling wave is deduced accordingly.Then,the concept of multi-frequency transmission coefficients is proposed by analyzing the amplitude-frequency,and the characteristics of each element.Finally,the LCC-VSCDC system model is built to verify the reliability and superiority of the principle itself.Theoretical analysis and experimental verification show that the principle has strong interference resistance.

A Double-Ended Protection Principle for an LCC-VSC-MTDC System with Strong Anti-Interference Ability

The DC grid technology of multi-power supply and multi-drop-point power reception is an effective solution for large-scale renewable energy integration into the power grid.Line-commutated converter-Voltage source converter(LCC-VSC)power grids are one of the more important developmental directions of the future power grid that have occured in recent years.But the multi-terminal high voltage direct current system has the problems of inconsistent boundary characteristics,inconsistent control,and fault response characteristics,which puts higher requirements on the protection scheme.Thus,a completely new protection principle is proposed in this paper.Firstly,the fault characteristics of distributed capacitance current are analyzed.The reactive power calculated by the distribution parameters of different frequencies is different.Subsequently,the fault characteristics of DC reactive power are analyzed,and a DC reactive power extraction algorithm is proposed.The polarity of the multi-band DC reactive power is used to construct the protection scheme.Finally,the LCC-VSC power grid model verifies the correctness and superiority of the proposed protection scheme.The proposed scheme uses DC reactive power instead of fault current to solve the long delay problem caused by distributed capacitance.Compared with the prior art,the proposed solution is not affected by distributed capacitance and has a stronger anti-interference ability(600Ω+10 dB+1 ms).

A Protection Method of VSC-HVDC Cables Based on Generalized S-Transform

Generalized S-transform is a time-frequency analysis method which has higher resolution than S-transform. It can precisely extract the time-amplitude characteristics of different frequency components in the signal. In this paper, a novel protection method for VSC-HVDC (Voltage source converter based high voltage DC) based on Generalized S-transform is proposed. Firstly, extracting frequency component of fault current by Generalized S-transform and using mutation point of high frequency to determine the fault time. Secondly, using the zero-frequency component of fault current to eliminate disturbances. Finally, the polarity of sudden change currents in the two terminals is employed to discriminate the internal and external faults. Simulations in PSCAD/EMTDC and MATLAB show that the proposed method can distinguish faults accurately and effectively.

The“Erga Omnes”of the Protection of Fundamental Human Rights and the“Complementary Protection”of Refugees Not Prescribed by the UN Convention Relating to the Status of Refugees

The United Nations Convention Relating to the Status of Refugees 1951 and its Protocol in 1967 set Four Essentials to limit the definition of "refugee". The concept of complementary protection emerged in academia and practice for those who, though they do not have the essentials,are in need of protection. Complementary protection is considered not only a moral obligation, but also a legal obligation. Although as the result of developing the principle of "non-refoulement" in international law, "complementary protection" should be limited when economic and social rights are concerned. The development of the non-refoulement principle and the emergence of "complementary protection" are based on the Erga Omnes of human rights. The International Court of Justice has restricted the emergence and evolvement of obligations Erga Omnes within the scope of obligations concerning fundamental and non-derogable human rights, and therefore,the application of "complementary protection" in protecting economic and social rights has been limited. Only when the unbalance of economic and social rights has been serious enough to impact other fundamental human rights will the obligation of "complementary protection" ensue.

On the Right to the Protection of Personal Data as a Constitutional Right

The right to the protection of personal data is an important human right in the era of big data and a constitutional right based on the national protection obligation and the theory of human dignity,making it of special significance for the realization of citizenship in a digital society.It can be seen from an examination of the constitutional texts of various countries in the world that the right to the protection of personal data as a constitutional right has rich normative connotations,and the key legal link to realize this right lies in the national legislature actively fulfilling its obligation to shape and specify the protection of personal data in accordance with the entrustment of the constitutional norms.Given the constitutional principles of fundamental rights protection,i.e.,realizing the constitutional status of the right to the protection of personal data as a basic right by means of institutional guarantees,the legislature should first adhere to the constitutionality principle of data protection legislation.Second,a multi-level data protection legal system centered on the right to the protection of personal data should be established.Finally,the institutional guarantee mechanism for the protection of personal data should be continuously improved through constitutional interpretation.

A Judicial Empirical Study on the Principle of “the Best Interests of the Child”——From the Principles of National Conventions to the Building of Adjudication Norms

“The best interests of the child”is an essential principle of the Convention on the Rights of the Child.Due to the abstractness and ambiguity of this principle,its application is inevitably subject to the judge’s personality.Through empirical analysis,we can find that the judicial documents invoking the principle of“the best interests of the child”by Chinese courts show a significant increase in the number of disputes,types of disputes,and pronounced regional characteristics.The application of this principle by the courts is highly consistent with the judicial interpretative documents issued by the Supreme People’s Court.The invocation of this principle plays the role of interpreting the provisions of the law,the value basis for discretion,and the value orientation for shaping new rules in adjudication.At the same time,it is plagued by a lack of guidelines for the application of principles,invocations that serve the will of judges,and imperfect thinking in weighing the various factors involved.The application of this principle should be improved by setting normative standards for the principle of“the best interests of the child”,increasing case guidance for invoking the principle,and enhancing the professionalism of judges.

Research of Pure Electric Ferry System and Its Short-Circuit Protection and Calculation

System control and safety reliability are important links of the marine DC (Direct Current) power system. The simulationmodel is built by Matlab/Simulink, the battery and super-capacitor are supplied to the system through a three-phase interleaved DC/DCconverter, the fuse and disconnector switch combination are used as the protection device, and the short-circuit point is set betweeneach branch and the DC distribution board, performing short-circuit simulation. This paper also proposes a short-circuit calculationmethod for super-capacitors based on the simplified model of series RC (Resistors & Capacitors), and verifies its correctness throughsimulation data. The results show that the introduction of a three-phase interleaved DC/DC converter reduces the current ripple andmakes the system control more convenient;short-circuit calculation and simulation have determined the short-circuit withstandcapability of the DC distribution board, and verified the feasibility of the fuse selection method and the short-circuit calculation methodof the super-capacitor. This provides reliable verification for the application and calculation of the actual project.

Review of protection and fault handling for a flexible DC grid

With the development of power electronics technology,the flexible DC grid will play a significant role in promoting the transformation and reformation of the power grid.It is immune to commutation failure and has high flexibility in power control and renewable energy grid integration.However,the protection and fault handling technology for a flexible DC grid is a big challenge because of the limited overcurrent capability of the converters.This paper summarizes the development of the flexible DC grid,and analyzes the fault characteristics in detail.Next,the applicability,advantages and disadvantages of the existing protection principle,fault isolation and recovery schemes are reviewed.Finally,the key problems and development trend of the future flexible DC grid are pointed out and forecasted respectively.

Pilot protection of hybrid MMC DC grid based on active detection

Considering the advantages and limitations of traditional identification method,combined with the strategy of active detection,the principle of DC grid pilot protection based on active detection is proposed to improve the sensitivity and reliability of hybrid MMC DC grid protection,and to ensure the accurate identification of fault areas in DC grid.By using the DC fault ride-through control strategy of the hybrid sub-module MMC,the fault current at the converter station DC terminal is limited.Based on the high controllability of hybrid MMC,sinusoidal fault detection signals with the same frequency are injected into the line at each converter station.Based on model recognition,the capacitance model condition is satisfied by the detected signals at both ends during external faults whereas not satisfied during internal faults.The Spearman correlation coefficients is then introduced,and the correlation discriminant of capacitance model is constructed to realize fault area discrimination of DC grid.The simulation results show that the active detection protection scheme proposed in this paper can accurately identify the fault area of DC grid,and is not affected by fault impedance and has low sampling rate requirement.

Mechanical analysis of effective pressure relief protection range of upper protective seam mining

This paper analyzes the control mechanism of coal and gas outbursts and proposes the concept of an effective pressure relief protection range, based on the stress relief of the underlying coal-rock mass and the development of a plastic zone. Also this study developed a stress change and fracture development model of the underlying coal-rock mass. In addition, the stress and depth of fracture of any point in the floor were deduced with the application of Maple Calculation Software. The specific engineering parameters of the Pingdingshan No. 12 colliery were applied to determine the relationship between the depth of fracture in the floor and the mining height. The pressure-relief principle of the underlying coal-rock mass was analyzed while varying the mining height of the upper protective seam. The findings indicate that as the depth of fracture in the floor increases, the underlying coal-rock mass experiences a limited amount of pressure relief, and the pressure relief protection range becomes narrower.Additionally, the stress distribution evolves from a ‘‘U" shape into a ‘‘V" shape. A 2.0 m mining height of protective seam situates the outburst-prone seam, Ji_(15), within the effective pressure relief protection range. The fracture development and stress-relief ratio rises to 88%, ensuring the pressure-relief effect as well as economic benefits. The measurement data show that: after mining the upper protective seam, the gas pressure of Ji_(15) dropped from 1.78 to 0.35 MPa, demonstrating agreement between the engineering application and the theoretical calculation.

A Novel Pilot Protection for VSC-HVDC Transmission Lines Based on Correlation Analysis

The control system of voltage source converter HVDC (VSC-HVDC) is complex and its fault tolerance ability is not sufficient, and correct rate of line protection device is not high. A novel pilot protection for VSC-HVDC transmission lines based on correlation analysis is proposed in this paper. In the principle, external fault is equivalent to a positive capacitance model, so the correlation coefficient of the current and voltage derivative is 1;while the internal fault is equivalent to a negative capacitance model, so the correlation coefficient of the current and voltage derivative is -1. Internal faults and external faults can be distinguished by judging the correlation coefficient. Theoretical analysis and PSCAD simulation experiments show that the new principle, which is simple, not affected by transition resistance, control type and line distributed capacitance current, can identify internal faults and external faults reliably and rapidly, having certain practical value.

Disinfection of Microbes by Magnetized DC Plasma

A different combined effects for helium gas discharge such as: magnetic field strength, breakdown voltage, applied power, applied pressure, cathode fall thickness, edge effect, distribution of the electron temperature and density, and finally exposure time for Staphylococcus aureus substrate over slides at the cathode edge, are discussed under the influence of cold, nonthermal plasmas, ultra low pressure, and presence of the magnetic field for disinfection of bacteria for short exposure times, compatible to International Commission on Non-Ionizing Radiation Protection, Health Phys (ICNIRP) for healing applications. Furthermore, analyses of the experimental data of initial and final densities of cells alive, using survival curves, showed an impressive inhibitory effect of plasma discharge to the remaining survival of bacterial ratio under the influence of the magnetic field.

A review on protection of DC microgrids

The DC microgrid has become a typical distribution network due to its excellent performance. However,a well-designed protection scheme still remains a challenge for DC microgrids. At present, researches on DC microgrids primarily focus on the topology structure, control method and energy control, while researches on fault analysis, detection and isolation have not drawn enough attention. Therefore, this paper intends to depict the current research status in different relative areas and review the proposed protection strategies in order to help researchers have a clear understanding on DC microgrid protection.Meanwhile, to solve the protection issues and promote the development of the DC microgrids, this paper points out the key areas of future researches. The future protection researchdirections lie in the development of novel protection devices, which are based on electronic technology to provide loose protection constraints and the improvement of suitable protection schemes. In addition, the novel concept of coordinated control and protection strategy in the DCmicrogrids is explained.

Hybrid ROCOV/Waveform Similarity Coefficient Based Protection for DC Lines in HVDC Grids

DC line protection with high speed and strong robustness against high fault resistance is essential in highvoltage direct current(HVDC)grids.The conventional voltagederivative-based protections for DC lines exhibit the problem of low reliability on the occurrence of high-impedance faults.In this paper,fault traveling waves at the fault point and at the line side of the DC reactor are first analyzed using phasemodal transformation.Based on the theoretical analysis of the modal fault-component voltages at the line side of the DC reactor,a novel hybrid protection scheme utilizing the single-ended rate of change of voltage(ROCOV)and waveform similarity coefficient is proposed.It utilizes the hybrid ROCOV criterion and waveform similarity coefficient to identify the faulted line and the amplitudes of the 0-and 1-mode fault-component voltages to identify fault type,and the polarities of the 0-and 1-mode fault-component voltages to identify faulted pole.Simulations under various fault conditions verify that the proposed protection scheme can achieve fast and reliable identification of faulted line,fault type,and faulted pole in 1 ms,and effectively improve the reliability against high-impedance faults up to 1200.

Key technologies for medium and low voltage DC distribution system

Development of the medium and low voltage DC distribution system is of great significance to a regional transmission of electric energy,increasing a penetration rate of new energy,and enhancing a safety of the operation of the AC/DC interconnected grid.This paper first summarizes the medium and low voltage DC distribution system schemes and plans put forward by many countries,and then elaborate status of under-construction medium and low voltage DC distribution system project cases in China.Based on these project cases,this paper analyzes key issues involved in the medium and low voltage DC distribution system topologies,equipment,operation control technologies and DC fault protections,in order to provide theoretical and technical reference for future medium and low voltage DC distribution system-related projects.Finally,this paper combines a current China research status to summarize and give a prediction about the future research direction of medium and low voltage DC distribution system,which can provide reference for the research of medium and low voltage DC distribution system.

International law obligations for the disposal of Fukushima nuclear-contaminated water under the principles of nuclear safety

The disposal of contaminated water from Japan’s Fukushima nuclear power plant is a significant international nuclear safety issue with considerable cross-border implications.This matter requires compliance not only with the law of the sea but also with the principles of nuclear safety under international law.These principles serve as the overarching tenet of international and China’s domestic nuclear laws,applicable to nuclear facilities and activities.The principle of safety in nuclear activities is fully recognized in international and domestic laws,carrying broad legal binding force.Japan’s discharge of nuclear-contaminated water into the sea violates its obligations under the principle of safety in nuclear activities,including commitments to optimum protection,as low as reasonably practicable,and prevention.The Japanese government and the International Atomic Energy Agency(IAEA)have breached the obligation of optimum protection by restricting the scope of assessments,substituting core concepts,and shielding dissenting views.In the absence of clear radiation standards,they have acted unilaterally without fulfilling the obligation as low as reasonably practicable principle.The discharge of Fukushima nuclear-contaminated water poses an imminent and unpredictable risk to all countries worldwide,including Japanese residents.Japan and the IAEA should fulfill their obligations under international law regarding disposal,adhering to the principles of nuclear safety,including optimum protection,the obligation as low as reasonably practicable,and prevention through multilateral cooperation.Specifically,the obligation to provide optimum protection should be implemented by re-evaluating the most reliable disposal technologies and methods currently available and comprehensively assessing various options.The standard of the obligation as low as reasonably practicable requires that the minimization of negative impacts on human health,livelihoods,and the environment should not be subordinated to considerations of cutting costs and expenses.Multilateral cooperation should be promoted through the establishment of sound multilateral long-term monitoring mechanisms for the discharge of nuclear-contaminated water,notification and consultation obligations,and periodic assessments.These obligations under international law were fulfilled after the accidents at the Three Mile Island and Chernobyl nuclear power plants.The implications of the principles of nuclear safety align with the concept of building a community of shared future for nuclear safety advocated by China.In cases of violations of international law regarding the disposal of nuclear-contaminated water that jeopardize the concept of a community of a shared future for nuclear safety,China can also rely on its own strength to promote the implementation of due obligations through self-help.