Estimation of multi-infeed HVDC inter converter direct current interaction in close electric proximity

This paper aims at investigating the direct current interaction between various converters of High Voltage Direct Current (HVDC) system, which lie in close electric proximity within the multi-infeed configuration. The interaction between converters in multi-infeed DC system are highly possible events which need to be evaluated in order to avoid the adverse operational results. The various indices such as multi-infeed interaction factor (MIIF) considering AC busbar voltages, local and concurrent commutation failures (CF) in converter stations under different AC disturbances, influence of AC system’s strength on fault recovery time (FRT), transient over-voltage (TOV) under permanent DC faults, voltage and power stability of multi-infeed DC system are comprehensively illustrated in literatures. However, there is lack of literature regarding the investigation of current interaction in multi-infeed DC system. Therefore, in this paper, a power flow approach is adopted to estimate the inter converter direct current interaction. An index, multi-infeed current interaction factor (MICIF) is proposed that can effectively depicts the interaction between converters. The MICIF index is verified through electromagnetic transient simulations of dual infeed HVDC system developed in PSCAD/EMTDC. The results show that MICIF index can accurately assess the interaction between different converter stations of HVDC system under steady and transient states

Excessive Use of Death Penalty as Stoppage Tool for Terrorism: Wrongful Death Executions in Pakistan

Wrongful death executions regardless of how infrequent, are a reminder of the fallibility of the justice system and a stain on its well-deserved reputation. The purpose of present study is to highlight the black evil of wrongful death executions in Pakistan while encountering terrorism. The data has been collected from World Justice Project, Pakistan Justice Project, newspapers and human rights reports. After an in-depth analysis of the literature and statistical data, our main findings reveals that incompetent investigation, judicial system, inadequate resources, outdated laws, institutional corruption and unclearly defined Anti-Terrorism Act 1997 lead to high level of wrongful executions under the cover of terrorism in Pakistan.  In addition, it transformational reforms are highly recommended in investigation agencies and judiciary at all level for the delivery of justice. Keywords: wrongful convictions; death executions; terrorism; criminal justice system DOI: 10.7176/JLPG/81-0

Honor Killing Phenomena in Pakistan

Honor killing is a persistent phenomenon not only in Pakistan but many other parts of the world. The paper addresses the case of Pakistan including the concept of honor killing, reasons, latest cases as well as the efforts to reduce the honor killing. The article also talks about the deficiencies left in the previous amendment that directly relevant to the problem but still not tackled by the legislature. The article analyzes the latest amendments, its improvements and the deficiencies that further need to be addressed to eradicate the problem forever. The paper in the last section also provide evidence of the compliance of international obligation regarding protection of women’s right. The article identifies the element that is keeping the practice of honor killing and recommend to amend the law to tackle that element as well. Keywords: honor killing, Pakistan, women’s right, CEDAW, amendmen

Study on Dynamic Characteristics of UHVDC System under Hierarchical Infeed Mode with STATCOM

This paper focuses on the investigation of the dynamic characteristics of Ultra High Voltage Direct Current (UHVDC) system Under Hierarchical Infeed Mode (UHVDC-HIM) with Static Synchronous Compensator (STATCOM). The STATCOM at the inverter side of UHVDC-HIM is developed in PSCAD/EMTDC, and their power flow equations are derived. Based on these equations, the control schemes for rectifier and inverter side of UHVDC-HIM and STATCOM are properly designed. Several dynamic characteristics indices such as Commutation Failure Immunity Index (CFII), Commutation Failure Probability Index (CFPI), fault recovery time and Temporary Overvoltage (TOV) are evaluated in detail. The impact of different sizes of STATCOM and Short Circuit Ratio (SCR) of AC sources on dynamic characteristics of UHVDC-HIM system during single-phase and three-phase faults are examined. The analysis shows that higher SCR values and greater capacity of STATCOM can make the UHVDC-HIM system less vulnerable to Commutation Failure (CF), considerably enhance the fault recovery time and effectively reduce the TOV

Operation and Challenges of Multi-Infeed LCC–HVDC System: Commutation Failure, AC/DC Power Flow, and Voltage Stability

This paper presents a detailed analysis of commutation failure, AC/DC power flow, and voltage stability of multi-infeed high-voltage direct current (HVDC). The use of HVDC power transmission technology has become common in modern power systems. During the past two decades, HVDC technology has been extensively used for long-distance bulk power transmission to remote areas. Throughout the world, the demand for power has drastically increased in recent years due to industrialization; such situations make HVDC an economic candidate because the distance between power generation plants and load areas is significantly very long. The line-commutated converter (LCC) technology-based HVDC system is well more mature than other available conversion schemes (i.e., voltage source converters), and it is widely used in high-power projects. China had approximately 50 HVDC–LCC links in 2020, and a single LCC-based link with the highest capacity is 12 GW. The installation of several HVDC links in an existing power network has led to a situation where two or more HVDC links terminate in the electric vicinity of each other’s AC network or even in same AC busbar. Such scenarios are termed multi-infeed HVDC system. Multi-infeed HVDC systems bring various challenges related to voltage stability, local and concurrent commutation failure, and AC/DC power flow. Here, the literature available on these phenomena of LCC-based HVDC is discussed for future research. The assumptions and drawbacks of various techniques used for investigating the mentioned phenomena are also highlighted

Analysis on Local and Concurrent Commutation Failure of Multi-infeed HVDC Considering Inter-converter Interaction

This paper provides a comprehensive analysis of local and concurrent commutation failure (CF) of multi-infeed high-voltage direct current (HVDC) system considering multi-infeed interaction factor (MIIF). The literature indicates that the local CF is not influenced by MIIF, whereas this paper concludes that both the local CF and concurrent CF are influenced by MIIF. The ability of remote converter to work under reduced reactive power enables its feature to support local converter via inter-connection link. The MIIF measures the strength of electrical connectivity between converters. Higher MIIF gives a clearer path to remote converter to support local converter, but at the same time, it provides an easy path to local converter to disturb remote converter under local fault. The presence of nearby converter increases the local commutation failure immunity index (CFII) while reducing concurrent CFII. Higher MIIF causes reactive power support to flow from remote converter to local converter, which reduces the chances of CF. A mathematical approximation to calculate the increase in local CFII for multi-infeed HVDC configurations is also proposed. A power flow approach is used to model the relation between MIIF and reactive power support from remote end. The local and concurrent CFIIs are found to be inverse to each other over MIIF; therefore, it is recommended that there is an optimal value of MIIF for all converters in close electric proximity to maintain CFII at a certain level. The numerical results of established model are compared with PSCAD/EMTDCsimulations. The simulation results show the details of the influence of MIIF on local CF and concurrent CF of multi-infeed HVDC, which validates the analysis presented

Biogas as sustainable approach for social uplift in South East Asian Region

The Asian region has rich agricultural resources that can be utilized for clean biogas technology. Few countries in Asia, namely China and Nepal, have developed policies and technologies for the biogas sector. Whereas Pakistan, a major agricultural country, cannot tap the bio-energy from the agriculture sector. This study aims to present a comprehensive policy analysis across different countries to identify the obstacles that impede the growth of the biogas sector in Pakistan. The research thoroughly reviews the most recent literature and policy documents and engages with stakeholders to gather their feedback on policy formulation. While most renewable energy policies predominantly focus on photovoltaic and wind energy resources, they tend to overlook the utilization of the available bioresources. Further, the absence of banking and microfinance institutions (MFIs) hampers the smooth flow of funds between donor agencies and farmers/end-users, which has proven to be a key factor for success in Nepal and China

From cloud computing to fog computing in Healthcare big data

In Healthcare big data, data is originated from various heterogeneous sources. Numerous novel base particular healthcare applications offered to handling source of data from electronic health record (EHR) to medical images. Imaging, Electronic Health Report, technology in light of sensor and numerous different procedures created an immense measure of Healthcare data. Cloud computing development was an excellent paradigm to substantiate big data which incited find of imperceptible examples. Cloud computing is a developing new registering design intended to answer different contending administrations on the Web. Fog Computing is a design style in which arrange segments amongst devices and the cloud execute application-particular rationale. We in this paper investigate, characterize, and talk about various application of cloud and fog computing. We talk about the impact of cloud computing and fog computing on healthcare big data. Cloud base framework for Homediagnosis Service, Fog computing architecture and the justification of moving from cloud to Fog presented comprehensively in this paper

From cloud computing to fog computing in Healthcare big data

In Healthcare big data, data is originated from various heterogeneous sources. Numerous novel base particular healthcare applications offered to handling source of data from electronic health record (EHR) to medical images. Imaging, Electronic Health Report, technology in light of sensor and numerous different procedures created an immense measure of Healthcare data. Cloud computing development was an excellent paradigm to substantiate big data which incited find of imperceptible examples. Cloud computing is a developing new registering design intended to answer different contending administrations on the Web. Fog Computing is a design style in which arrange segments amongst devices and the cloud execute application-particular rationale. We in this paper investigate, characterize, and talk about various application of cloud and fog computing. We talk about the impact of cloud computing and fog computing on healthcare big data. Cloud base framework for Homediagnosis Service, Fog computing architecture and the justification of moving from cloud to Fog presented comprehensively in this paper