Abstract

The improvement of the automation level in electricity-heat integrated energy systems (IESs) has laid foundation for the load transfer after contingencies. As the energy coupling core and energy supply source, the energy hub (EH) plays an important role in IESs, where the load of EH’s pipeline segment outlets is defined as operating points. First, the model of security region (SR) is proposed with the consideration of EH’s equipment and pipeline segment N-1 contingencies and the system normal operation. Second, based on the security boundary of SR, the distance from an operating point to a boundary is presented for security assessment. Finally, the effectiveness of the proposed SR model and security assessment method is demonstrated on a test case, which can provide guidance for dispatchers.

Abstract

As the core component of the energy coupling link of integrated energy system, the regional energy station undertakes important tasks such as energy allocation and controlling, so it’s imperative to study the energy management strategy of it. This paper proposes a double auction based energy management strategy of the energy station. The energy station model and load bidding model are explored. The electricity-heat coordinated market model is constructed to achieve the coordinated clearing of electricity and heat, optimizing the resource allocation. The case study demonstrates that the proposed method can optimize energy production and usage, saving energy cost for energy station and users.

Abstract

With the high penetration of distributed generators (DGs), it puts higher requirements on the operational flexibility of active distribution networks (ADNs). Operational flexibilities are from controllable resources (CRs) within the feeders. However, due to the secure operational constraints of distribution network, the flexibilities of CRs cannot be fully translated into feeder operational flexibilities. In this paper, to quantify the feeder operational flexibility for flexible, efficient and secure operation of ADNs, a quantification analysis method is proposed. The definition and mathematical expression of feeder operational flexibility are proposed firstly. By constructing a multi-dimensional state space, state equations of operational constraints are presented. Then an analytical framework for quantifying the feeder operational flexibility in ADNs is proposed. Finally, based on Monte Carlo simulation, case studies are performed on the modified IEEE 33-node system.

Abstract

As the development of Renewable Energy Sources (RES) technologies increases, the problem of intermittency and variability from the RES integration into the grid arises for system planners. Therefore, this paper presents a dynamic multi-objective optimization model for the generation and transmission expansion planning (GTEP) problem with consideration to renewable energy sources. The proposed mathematical model minimizes the investment costs for transmission network and renewable energy expansion planning, operation costs and emissions for fossil fuel generating units as well as maximizes the economic incentives for utilizing renewable energy generating units. The dynamic planning strategy for the optimization problem is to consider the annual investment decisions associated with renewable energy sources integration and its effects on the GTEP procedure. The developed model is solved using CPLEX 12.8.3 and applied to a Garver’s six bus test system and the numerical results show that the dynamic model permits system planners to adjust the system to future changes with time and ensures more utilization of renewable energy sources annually.

Abstract

Mini-grids powered by renewable energy sources have periods of high and low energy production due to variability in resources. The reliability of power supplied from such systems can be significantly improved by incorporating energy storage systems. This study investigates the use of energy storage – pumped hydro systems and hydrogen fuel cells – in a mini-grid system for operational cost reduction and system reliability improvement. The hybrid system’s power output is modelled with the objective of simultaneously minimising fuel costs while ensuring system reliability. The proposed mathematical model is verified using realworld data of KwaZulu Natal site in South Africa. The simulation results show that small-sized pumped hydro systems (PHS), in combination with Hydrogen Fuel Cells (HFC) can significantly reduce fuel costs of diesel generators in off-grid systems by 69% in summer and 34% in winter

Abstract

This paper presented a methodology of artificial neural network (ANN) for the prediction of flow patterns in two-phase air-water flow along upward inclined pipes. In the built ANN model, superficial velocity of air, superficial velocity of water, and inclined angle were set as inputs while the quantified flow patterns were defined as the output. In total, 1952 experimental data points that were reported in the literature were trained and tested by the designed network structure. The predicting accuracies of stratified smooth, stratified wavy, annular, intermittent, bubble flow are all above 90%, with the exception of dispersed bubble flow.

Abstract

Consumption of fossil fuel resources leads to serious economic and environmental issues such as (high fossil fuel subsidies, high carbon emissions, and high energy demand). This current economic situation needs new methods, which should generate sustainable solutions that are mostly independent of the use of fossil fuels. However, there are many barriers to the development of renewable energy. Based on the literature the major barriers to renewable energy are economic, Policy and legal, and technical. A literature review was performed in this paper to determine the reasons for shifting from conventional energy to renewable energy and identifies the barriers to the development of renewable power generation.

Abstract

The integrated community energy system (ICES) has aroused considerable attention for its low emission and high operating efficiency. The existing planning methods for ICES with multi-energy sectors ignored the deferrable load. In this paper, a two-stage planning method of ICES is developed to achieve the minimum annual investing and operating cost. At the first stage, the capacities of components in ICES are optimized to minimize the annual investment cost of ICES. At the second stage, the annual operating cost including the electricity and gas purchase costs and the component maintenance cost is minimized to satisfy the energy load. The deferrable load under the time-of-use energy price in seasonal typical days is considered in the second stage. Relevant simulations are conducted to validate the effectiveness of the proposed planning method for ICES. Considering the deferrable load, comparative simulations illustrate that the proposed planning method can significantly reduce the battery investment cost.

Abstract

Large-scale wind farm integration poses serious challenges to the operation and control of power systems. Real-time simulator is an effective tool to reproduce the dynamics within wind farms and the influence on the system. In this paper, a novel design of real-time simulator for permanent magnet synchronous generator (PMSG) based wind farms is proposed using pipeline technique, which can realize the high-efficiency simulation under limited hardware resources compared with traditional method. With the proposed design, a PMSG based wind farm is simulated, and the simulation results are compared with PSCAD/EMTDC to validate the correctness and effectiveness of the design.

Abstract

The multi-scenario operation of the energy storage system (ESS) improves its economy and makes it more widely used in the power grid. By categorizing the operation scenario into the periodic running and triggering running scenarios, a novel optimal control strategy for the ESS under multi-scenario operation is presented in this paper. In order to evaluate the maximum input/output power of ESS, a new power capability index (PCI) is defined. Base on the PCI, the peak-shaving optimization model is built. Then the dynamic programming algorithm is used to solve this model. Evaluated on a 10kV substation in Shanghai, the proposed control strategy effectively alleviates the peak load pressure of power supply and responds the operation commands by different roles in the power system efficiently.