Peak Shaving Strategy Research Articles

Assessing the Demand Side Management Potential and the Energy Flexibility of Heat Pumps in Buildings

The energy demand in buildings represents a considerable share of the overall energy use. Given the significance and acknowledged flexibility of thermostatically controlled loads, they represent an interesting option for the implementation of demand side management (DSM) strategies. In this paper, an overview of the possible DSM applications in the field of air conditioning and heat pumps is provided. In particular, the focus is on the heat pump sector. Three case studies are analyzed in order to assess the energy flexibility provided by DSM technologies classified as energy efficient devices, energy storage systems, and demand response programs. The load shifting potential, in terms of power and time, is evaluated by varying the system configuration. Main findings show that energy efficient devices perform strategic conservation and peak shaving strategies, energy storage systems perform load shifting, while demand response programs perform peak shaving and valley filling strategies.

Tandem Cell-Based Vanadium Redox Flow Battery Stack

Today about two-thirds of the world’s total electric power is generated from fossil fuels and nuclear based energy. Globally accelerating concerns regarding environmental pollution from the burning fossil fuels in combination with increasing energy shortages have provoked great interest in the generation of electrical energy from renewable sources such as wind and solar [1-3]. However, the random and intermittent nature of these power sources induces low-quality output in electricity, which affects the stability of the grid. Given that energy storage system (ESSs) can be efficiently balanced between power generation and the consumption of renewable energy sources through load-leveling and peak-shaving strategies, they have emerged as a key technological challenge [4-5]. Among various types of ESSs, the all-vanadium redox flow battery (VRFBs) is a promising technology for large scale electrical energy storage systems. These batteries utilize the reduction and oxidation reaction of two active species in the electrolytes for charge and discharge processes. VRFBs can independently be the scalable application which shows power and energy capacity component of the system [6,7]. In this study, we report in detail our investigation of Tandem electrode structure for VRFB system and its effect on long-term stability and electrochemical performance. [1] Z. Yang, J. Zhang, M.C. Kintner-Meyer, X. Lu, D. Choi, J.P. Lemmon, J. Liu, Chem. Rev., 111 (2011) 3577-3613. [2] B. Dunn, H. Kamath, J.-M. Tarascon, Science, 334 (2011) 928-935. [3] C. Koroneos, T. Spachos, N. Moussiopoulos, Renewable energy, 28 (2003) 295-310. [4] D. Wang, Z. Geng, B. Li, C. Zhang, Electrochim. Acta, 173 (2015) 377-384. [5] H. Chen, T. N. Cong, W. Yang, C. Tan, Y. Li, Y. Ding, Progress in Natural Science, 19 (2009) 291-312. [6] H. Kaneko, K. Nozaki, Y. Wada, T. Aoki, A. Negishi, M. Kamimoto, Electrochim. Acta , 36 (1991) 1191-1196. [7] M. Skyllas‐Kazacos, C. Menictas, M. Kazacos, J. Electrochem. Soc., 143 (1996) L86-L88.

Backstepping Control of Smart Grid-Connected Distributed Photovoltaic Power Supplies for Telecom Equipment

Backstepping controllers are obtained for distributed hybrid photovoltaic (PV) power supplies of telecommunication equipment. Grid-connected PV-based power supply units may contain dc-dc buck-boost converters linked to single-phase inverters. This distributed energy resource operated within the self-consumption concept can aid in the peak-shaving strategy of ac smart grids. New backstepping control laws are obtained for the single-phase inverter and for the buck-boost converter feeding a telecom equipment/battery while sourcing the PV excess power to the smart grid or to grid supply the telecom system. The backstepping approach is robust and able to cope with the grid nonlinearity and uncertainties providing dc input current and voltage controllers for the buck-boost converter to track the PV panel maximum power point, regulating the PV output dc voltage to extract maximum power; unity power factor sinusoidal ac smart grid inverter currents and constant dc-link voltages suited for telecom equipment; and inverter bidirectional power transfer. Experimental results are obtained from a lab setup controlled by one inexpensive dsPIC running the sampling, the backstepping and modulator algorithms. Results show the controllers guarantee maximum power transfer to the telecom equipment/ac grid, ensuring steady dc-link voltage while absorbing/injecting low harmonic distortion current into the smart grid.

Selection of a suitable energy management strategy for a hybrid energy system in a remote rural area of India

Renewable energy, a viable alternative of the world, can overcome the energy crisis that hinders growth of today's economies. The present work includes sizing of hybrid energy system using various energy management strategies. The energy management strategies considered in the present work are cycle charging strategy, load following strategy and peak shaving strategy. The sizing of hybrid energy system for all the mentioned strategies are carried out using genetic algorithm, particle swarm optimization and biogeography based optimization techniques by keeping energy index ratio at 1. The model also incorporates net present cost, cost of energy, renewable fraction and emissions of carbon di-oxide from diesel generator. From the analysis, it can be concluded that the 10th combination of cycle charging strategy is most cost effective as compared to other dispatch strategies. Seven unelectrified villages of Dhauladevi block of Almora district in Uttarakhand, India, has been selected for the development of hybrid energy system, comprising of renewable energy resources available locally along with the addition of diesel generator, for meeting the energy deficit. The results show that cycle charging strategy is most cost effective compared to load following and peak shaving strategies, with a minimum cost of energy value of 5.64 ₹/kWh.

A Controllable Local Peak-Shaving Strategy for Effective Utilization of PEV Battery Capacity for Distribution Network Support

Plug-in electric vehicles (PEVs) have a potential amount of battery energy storage capacity, which is not fully utilized in regular day-to-day travels. The utilization of spare PEV battery capacity for grid support applications using vehicle-to-grid concept is becoming popular. Depending on the stress on the grid during peak load periods, a small amount of peak-shaving support from the PEVs in a feeder can be useful in terms of grid support. However, as the PEV batteries have limited capacity and the capacity usage is also constrained by travel requirements, a strategy is proposed in this paper for an effective utilization of the available PEV battery capacity for peak shaving. A controllable discharging pattern is developed to most utilize the limited PEV battery capacity when peak shaving is most valuable based on the demand pattern. To ensure an effective use of the available PEV battery capacity for travel, which is the main usage of the PEVs, and for grid support application, dynamic adjustments in PEV discharging rates are made. The effectiveness of the proposed strategy is tested using a real distribution system in Australia and based on practical PEV data.

Analysis of control strategies for thermally activated building systems under demand side management mechanisms

Thermally activated buildings systems (TABS) are systems that integrate heating/cooling devices in the building structure, so that the building elements act as thermal storage and have an active role in the energy supply and demand management. Although TABS are well known systems, there are still open questions in their realization, mainly concerning appropriate control strategies which are influenced by the large thermal inertia. The purpose of this paper is to analyze the influence of demand side management control strategies on the performance of a thermally activated building system applied in a commercial building. The goal is to estimate the potential of TABS for load shifting requested by the electricity grid. The analysis is performed by means of a sample case: first the existing TABS control strategy and then the possible implementation of DSM mechanisms are analyzed. In particular three different demand side management mechanisms are evaluated: (i) a peak shaving strategy, (ii) a random request of switching on/off the system and (iii) a night load shifting strategy. The simulation results show high potential of TABS within the DSM framework, since TABS allow load control while scarcely affect thermal comfort.

Generation expansion planning including the renewable energy sources

The authors study the long-term competitiveness of introducing renewable energy sources alongside the conventional generating units in a generation expansion plan by linking a short-term study and a long-term planning model. The short-term study is an extensive examination of the different combinations of the renewable energy sources which can operate with the conventional generating system for different objectives. These objectives are varied between two general strategies: the fuel-saver strategy and the peak-shaving strategy. In long-term planning, these combinations are considered as decision variables. For this purpose, a long-term generation expansion planning model is used to decide which strategy can be used and the capacity as well as the time of addition.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>