The explosive growth of various services boosts the innovation and development in terrestrial communication systems for the implementation of the next generation mobile communication networks. However, simply utilizing limited resources in terrestrial communication networks is difficult to support the massive quality of service (QoS) aware requirements and it is hard to guarantee seamless coverage in far remote regions. Leveraging the intrinsic merits of high altitude and the ability of multicasting or broadcasting, satellite communication systems provide an opportunity for novel mobile communication networks with its tight interaction and complementary characteristics to traditional terrestrial networks. It is believed that the convergence of satellite and terrestrial networks can solve the problems existing in current mobile communication systems and make a profound effect on global information dissemination. In this paper, we make a comprehensive survey on the convergence of satellite and terrestrial networks. First, motivations and requirements of satellite-terrestrial network convergence are identified. Then, we summarize related architectures of existing literature, classify the taxonomy of researches on satellite-terrestrial networks, and present the performance evaluation works in different satellite-terrestrial networks. After that, the state-of-the-art of standardization, projects and the key application areas of satellite-terrestrial networks are also reviewed. Finally, we conclude the survey by highlighting the open issues and future directions.

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Convergence of Satellite and Terrestrial Networks: A Comprehensive Survey

Metrics and enhancement strategies for grid resilience and reliability during natural disasters

In the absence of traditional communication infrastructures, the choice of available technologies for building data collection and control systems in remote areas is very limited. This paper reviews and analyzes protocols and technologies for transferring Internet of Things (IoT) data and presents an architecture for a hybrid IoT-satellite network, which includes a long range (LoRa) low power wide area network (LPWAN) terrestrial network for data collection and an Iridium satellite system for backhaul connectivity. Simulation modelling, together with a specialized experimental stand, allowed us to study the applicability of different methods of information presentation for the case of transmitting IoT data over low-speed satellite communication channels. We proposed a data encoding and packaging scheme called GDEP (Gateway Data Encoding and Packaging). It is based on the combination of data format conversion at the connection points of a heterogeneous network and message packaging. GDEP enabled the reduction of the number of utilized Short Burst Data (SBD) containers and the overall transmitted data size by almost five times.

Study of Data Transfer in a Heterogeneous LoRa-Satellite Network for the Internet of Remote Things

A review on operation and maintenance of hydropower plants

This work describes system engineering of an internet-of-things (IoT) connectivity and satellite data transfer for a pico-hydroelectric power generation system. The system is developed for deployment in remote villages in the Nepal Himalayas. The IoT devices are sensors attached to various points in the system which monitor critical system performance metrics such as generator vibrations and output voltage and control important functions. The data is transmitted from IoT devices using Zigbee. The data is then transmitted to the Iridium satellite system so it can be available to an international team of researchers who developed and monitor the performance of the system. This allows for optimization and performance improvements with the goal of perfecting the system so it can be implement in other villages. This work describes the system, why it is needed, and the hardware. The result is an IoT enabled monitoring system with real time data transmitted using satellites.

IoT enabled pico-hydro electric power with satellite back haul for remote himalayan villages

This paper presents the baseline concept for a multi-year system development of a pico-hydroelectric power system in Nepal. Prior work on pico-hydro systems has focused on one or a few of the factors required for value sustainment over the full life cycle of the system. In contrast to prior investigations, this work provides a systems engineering approach to generate a highly contextualized solution which considers the geographical and cultural needs of the users and other stakeholders. This approach is taken to overcome the limitations of prior systems and to engineer the system in a way that accounts for the needs of the users. Therefore, user's needs are examined and a clear assessment of prior local pico-hydro systems is performed. The result is a list of seven key reasons that prior systems failed early in their expected life cycle. A baseline concept is developed which overcomes these limitations and is tailored to the context of the community. One of the unique results of this work is that it provides an example of how green energy solutions for rural applications should be highly contextualized to ensure maximum impact and long term sustainment. Another result is a viable baseline concept for a green electric power solution in remote rural locations.

Pico-Hydro Electric Power in the Nepal Himalayas

Remote, high-altitude villages in the Nepalese Himalayas belong to the poorest and most underdeveloped communities in Nepal, with many still years/decades away from access to electricity. It is common that first-time electrification of these villages is through a 15–50 kW micro-hydropower (MHP) system, subsidized by the Nepal government. The majority of the so far installed MHP systems in the region are however within 3–12 months after they have been commissioned either inoperable due to premature equipment breakage, inappropriate operation, and absent maintenance or do not provide the expected power output. No mechanism is put in place to build an operating and maintenance fund, further putting the longevity of the system at risk. The “dreams” of villagers, promised by such development projects, remain unfulfilled and most often shattered. This paper describes a modular pico-hydropower (PHP) system (1–5 kW) being pursued in the village of Moharigaun in the Jumla district of Nepal whose capacity can be expanded as the village’s power demand, population, and ability to operate and maintain the system grow. This modular PHP system provides reliability through redundancy and the elimination of some of the more maintenance-prone components. The turbine water and electricity delivery infrastructure are buried to protect them from the elements and potential mischief. Most importantly, a prepayment system with remote disconnect capability ensures households pay into an operations and maintenance fund. The whole village community is actively involved in each step of the project (planning, implementation stages, and training), so they will develop a strong ownership for their PHP system. Further, local people, chosen by the community, will be trained to properly operate, administer, and maintain the PHP system.

Modular Pico-hydropower System for Remote Himalayan Villages

We describe the Internet-of-Things (IoT) network, the Arduino platform and integrated development environment (IDE), and the JSON communications protocol, to manage a pico-hydroelectric system in a Himalayan Nepalese village. This demonstrates the usability and reliability of open-source IoT devices and platforms in critical green energy infrastructure at difficult-to-reach places. The local system utilizes an RS-485 network that connects five nodes: power room, turbine room, village bathwater tank, a community center bathwater tank, and a biogas digester tank. The power room node contains the master controller of the monitoring and utilization network. The turbine room node consists of a Failsafe module that monitors the voltage, temperature, and water pressure of the turbines. The Failsafe is critical for automatically dumping dangerous excess generated power into the river. The community center and village bathwater nodes, and the biogas digester node, consist of AC Relay modules that monitor the temperatures and send power to their resistive loads on command from the power room, based on village user selected priorities and current energy availability. Close to 100% utilization of the generated power has been achieved, bringing significant benefits to the villagers.

IoT Sensing and Control Network for Pico-Hydroelectric in the Nepal Himalayas

This paper describes a Prioritized Load Control System (PLCS) developed to improve the overall utilization factor of pico-hydroelectric systems. A pilot project utilizing this PLCS in a remote rural Himalayan village has been operating since November 2018. The system uses traditional diversion load, incorporating a commercial PWM diversion controller to automatically and dynamically maintain a constant load on the turbines, diverting excess power to air heater resistors in the community center. We developed a programmable AC Load Controller that adds or removes useful 230VAC electrical loads based on commands from a central control computer. It diverts power to ubiquitous and inexpensive 230VAC water heater elements, over the existing 230VAC power distribution network, to heat water tanks for useful purposes. The central control computer adds and removes power to each of the prioritized loads in the system based on their priority, their need for additional energy, and on the availability of sufficient power. An electrical and mechanical interface to temperature sensors is incorporated into the AC Load Controller to monitor the temperature of the water heated by these loads. Voltage and current sensors are also included to monitor overall system performance and utilization. The AC Load Controller and the PWM diversion load controller are integral parts of the PLCS used to improve the utilization factor of the electric system to close to 100% (neglecting parasitic losses), sending power to heat water for showers, to heat the slurry in a prototype high altitude biogas digester, and to heat the community center. This paper describes the AC Load Controller in detail.

Mark Stambaugh

Papers

IoT enabled pico-hydro electric power with satellite back haul for remote himalayan villages

Pico-Hydro Electric Power in the Nepal Himalayas

Modular Pico-hydropower System for Remote Himalayan Villages

IoT Sensing and Control Network for Pico-Hydroelectric in the Nepal Himalayas

Prioritized Load Control System for Pico-Hydroelectric Power in the Nepal Himalayas