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The share of voltage source converter (VSC) technology is increasing in conventional power systems, and it is penetrating into specific transportation systems such as electric vehicles, railways, and ships. Researchers are identifying feasible methods to improve the performance of railway electrification systems (RESs) by utilizing VSC-based medium-voltage direct current (MVDC) railways. The continuous motion of electric trains makes the catenary resistance a variable quantity, as compared to the traction substation (TSS), and affects the currentsharing behavior of the system. A modified droop control technique is proposed in this paper for VSC-based MVDC RES to provide more effective current-sharing while maintaining catenary voltages above the minimum allowable limit. The droop coefficient is selected through an exponential function based on the ratio between the concerned TSS current and the system average current. This enables small adjustments of droop values in less concerning marginal current deviations, and provides higher droop adjustments for large current deviations. Meanwhile, the catenary voltages are regulated by considering the voltage data at the midpoint between two TSSs, which experiences the lowest voltages owing to the larger distance from the TSSs. The proposed techniques are validated via simulations and experiments.

Innovative advancement in power electronics is reshaping the conventional high-voltage transmission systems and has also opened a new paradigm for researchers to consider its benefits in the railway electrification system (RES). In this regard, the medium-voltage direct current RES (MVDC-RES) is a key area of interest nowadays. In this paper, a secondary energy source (SES) consisting of renewable energies (REs) and energy storage systems (ESSs) is proposed to solve the issues of catenary voltage regulation, rail potential, and stray current in the MVDC-RES. Some of the major integration topologies of the SES are analyzed for MVDC-RES and the most effective one is proposed and implemented. The voltage at the point of connection (PoC) of the SES is used as a reference for controlling different operation modes of REs and ESSs. Moreover, feedforward control is used at the ESS converter to attain the quick response from the batteries for the desired operation. The proposed scheme improves the catenary voltage, and reduces the rail potential and stray current. Besides, the scheme provides higher energy density and reduces line losses. Simulation results are provided to validate the operation modes and advantages of the proposed scheme.

Grim issue of Electricity shortages in most of developing countries leads to explore the potential in renewable and economical sources of energy. Power generation through Waste To Energy (WTE) Plants is an effective way to deal with the problems of MSW management and electricity shortages in densely populated cities of the world. In this paper, capacity estimation of Power generation from Municipal Solid Waste (MSW) of Peshawar city through Solid Waste Fueled Power Plant (SWFPP) is analyzed. For effective estimation of power generation through WTE plant, a detail study about estimation of Municipal Solid Waste of Peshawar city, composition and characteristics of collected waste, appropriate conversion technology; heat generated from it and ultimate power generation is discussed.

In contrast to the conventional direct current railway electrification system (DC-RES), the medium voltage direct current (MVDC)-RES is considered promising for long-distance high-speed corridors. In the MVDC-RES, traction substations (TSSs) are placed much farther and train loads are much heavier than in the conventional DC-RES. Hence, the MVDC-RES brings a drastic change in catenary voltage, TSS spacing, and train loading, which affects rail potential and stray current. In this connection, this work performs some significant quantitative analysis of rail potential and stray current in the MVDC-RES environment. An MVDC simulation model is proposed and different grounding schemes are analyzed for a single-train and two TSSs scenario as well as for a multi-train multi-TSS scenario. According to the simulation and analysis, the maximum values of rail potential and stray current at MVDC-RES distances and the maximum safe distance between adjacent TSSs are determined.

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