Hybrid Power System for the Range Extension of Security Robots: Prototyping Phase

This paper describes our best practices related to hybrid power system (HPS) development with a focus on the prototyping phase. Based on the main development goals of our security robot, 24 h continuous operation on a single charge as a top priority, the HPS specifications were developed in the previous phase. For long-duration missions, batteries are hybridized with hydrogen fuel cells. By hybridization, the practical issues of fuel cells can be addressed such as lack of durability and low power density. With the developed specifications of the HPS, its components were acquired and installed to build a prototype. Using an electronic load coupled with a charge-discharge system controller, the constructed prototype was tested, discovering the maximum output power (850 W) that the fuel cell can sustain for 24 h. To further increase the energy density of the HPS, its structure was converted to a plug-in hybrid. With the developed HPS simulator, the converted HPS was simulated, predicting an extended hours of operation (2.07 h) based on the larger battery (7S12P) over the widest SOC window (90%). The plug-in HPS prototype was integrated into the security robot. On a dedicated chassis dynamometer, the integrated prototype was tested, demonstrating its capability to continuously operate the security robot for 24 h.

Isolated and Interconnected Multi-Area Hybrid Power Systems: A Review on Control Strategies

Concerned with the increasing greenhouse gases in the atmosphere due to fossil fuels, the entire world is focusing on electricity generation through renewable energy resources. The most advantageous aspect of the distributed renewable sources is to provide the electricity to remote, scattered and the deprived rural areas by developing the hybrid power system at the smaller scale where power transmission through grid extension is not viable due to some economical, technical or environmental constraints for building new transmission lines. An accurate and adequate control strategy becomes inevitable to uphold the smooth operation by restraining the frequency and voltage deviation within its limit ensuring the highest degree of reliability of hybrid power system to provide an adequate power quality. In this paper, a comprehensive review of different control strategies adopted in isolated and interconnected multi-area hybrid power systems is presented.

Hybrid Power System for the Range Extension of Security Robots: Specification Development Phase

This paper describes our best practices related to hybrid power system (HPS) development, with a focus on the specification development phase. The HPS specifications are based on the main development goals of our security robot, which place top priority on 24 h continuous operation on a single charge. Similar to human guards, security robots are expected to operate 24 h per day, seven days per week, but existing battery-powered robots cannot meet these goals. For long-duration missions, their operating times are too short, and their charging times are too long. As an effective alternative, hydrogen fuel cells are combined with batteries to hybridize the power systems of security robots. In this study, several HPS structures were comprehensively compared by selecting a one-stage series structure. Component specifications were determined based on the selected structure to achieve the main development goals of our security robot. To verify whether the determined specifications are valid, a HPS simulator was developed. The key operating conditions for the HPS were simulated, including overloading, terminal short-circuiting, and drive cycling. Under critical conditions, the behavior of the entire system and its components was confirmed. The developed specifications will eventually be carried over to the prototyping phase.

Equivalent Firm Capacity Assessment of HDR-PV Hybrid Power System: A Distributionally Robust Approach

Aiming at the reliable grid connection of photovoltaic (PV) systems in frigid plateau regions, this work first designs a flexible hot dry rock (HDR) hybrid power system (HPS), making full use of the potential of HDR for energy storage and power generation. Based on the operation of HPS, a comprehensive energy system credible capacity assessment method considering the overall economy of the system and the reliability of the grid is established. In this method, the power allowable fluctuation rate of the grid as the equivalent firm capacity (EFC) constraint is considered. Then, the constraint is converted into a set of linear chance conditions through the distributionally robust method so that the capacity assessment of the HDR-PV HPS can be converted into a mixed-integer linear optimization problem for a solution. The proposed assessment method is verified by real HDR-PV HPS in the Gonghe Basin of Qinghai Province. The results show that the flexible HDR plant increases the credible capacity of the HPS by 113.38%. The profit of the flexible HDR plant was increased by 3.02% at the same time. The parameter analysis shows that the HDR-PV HPS obtains the most profit when the allowable fluctuation rate is 7%, but 10% can fully utilize the geothermal. The assessment method can effectively assess the credible capacity of the system under the premise of ensuring the overall economy of the HPS, thereby guiding power grid dispatching.