Solar Engineering Of Thermal Processes

Recent advancements in supercapacitor technology

Changes in the electricity business environment, dictated mostly by the increasing integration of renewable energy sources characterised by variable and uncertain generation, create new challenges especially in the liberalised market environment. The role of energy storage systems (ESS) is recognised as a mean to provide additional system security, reliability and flexibility to respond to changes that are still difficult to accurately forecast. However, there are still open questions about benefits these units bring to the generation side, system operators and the consumers. This study provides a comprehensive overview of the current research on ESS allocation (ESS sizing and siting), giving a unique insight into issues and challenges of integrating ESS into distribution networks and thus giving framework guidelines for future ESS research.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-gtd.2015.0447

Review of energy storage allocation in power distribution networks: applications, methods and future research

This paper proposes a coordinated operational dispatch scheme for a wind farm with a battery energy storage system (BESS). The main advantages of the proposed dispatch scheme are that it can reduce the impacts of wind power forecast errors while prolonging the lifetime of BESS. The scheme starts from the planning stage, where a BESS capacity determination method is proposed to compute the optimal power capacity and energy capacity of BESS based on historical wind power data; and then, at the operation stage, a flexible short-term BESS-wind farm dispatch scheme is proposed based on the forecasted wind power generation scenarios. Three case studies are provided to validate the performance of the proposed method. The results show that the proposed scheme can largely improve the wind farm dispatchability.

/pdf/coordinated-operational-planning-for-wind-farm-with-battery-3nq5869juf.pdf

Coordinated Operational Planning for Wind Farm With Battery Energy Storage System

A novel stochastic planning framework is proposed to determine the optimal battery energy storage system (BESS) capacity and the year of installation in an isolated microgrid using a new representation of the BESS energy diagram. The BESS enhances microgrid operation via load leveling and reserve provisions in conjunction with the spinning reserve from dispatchable distributed generation (DG) units. A decomposition-based approach is proposed to solve the problem of stochastic planning of BESS under uncertainty. The optimal decisions minimize the net present value (NPV) of total expected costs over a multiyear horizon taking into consideration the optimal BESS operation considering a novel matrix representing BESS energy capacity degradation. The proposed approach is solved in two stages as mixed-integer linear programming problems to ensure the convergence of the stochastic optimization problem. The optimal ratings of the BESS are determined in the first stage, while the optimal installation year is determined in the second stage. The approach ensures utilizing the allocated budget effectively by performing several iterations. Extensive studies considering four types of BESS technologies for deterministic, Monte Carlo Simulations, and stochastic cases are presented to demonstrate the effectiveness of the proposed approach.

Stochastic Optimal Planning of Battery Energy Storage Systems for Isolated Microgrids

https://onlinelibrary.wiley.com/doi/epdf/10.1002/2050-7038.12128

Effects of decreasing synchronous inertia on power system dynamics—Overview of recent experiences and marketisation of services

As installed wind capacity of the world increases, more and more issues are revealed during operation. One of these issues is related to the stochastic nature of wind speed that results in low accuracy of wind power forecasts. That is why energy storage becomes increasingly important. In this paper, a simulation tool is introduced developed to simulate the cooperation of a grid-connected wind farm and a generic energy storage unit. The aim of the tool is to decrease the difference between forecasted and actual wind power production. After the introduction of today's forecasting methods, the rule-based simulation tool is detailed. The operation of the tool is demonstrated using data of the Hungarian wind farms. Rated power and capacity is then calculated for a generic energy storage unit that is able to keep the resulting output of Hungarian wind farms and the belonging energy storage inside the ±50% range of the forecasted power, 95% of the time.

Cooperation of a Grid-Connected Wind Farm and an Energy Storage Unit—Demonstration of a Simulation Tool

The fluctuated nature represents the main obstacle for increasing the penetration level of photovoltaic (PV) generators in utility microgrids. The energy storage systems (ESSs) represent the main solutions to get over these fluctuations. Among various ESSs, the superconducting magnetic energy storage (SMES) systems have proven themselves as an effective solution. The SMES control systems in the literature result in a shortened lifetime, degraded thermal behavior, and high AC losses in the SMES. Thence, reliable operation of SMES systems and microgrids has been given wide concerns due to the large fluctuations in microgrids with high levels of PV penetrations. This paper presents a SMES-based fuzzy logic approach for improving the reliability of SMES and utility microgrids with high PV penetration levels. The proposed SMES controller employs the state of charge (SOC) of SMES as an input. This, in turn, can effectively extend the lifetime of SMES due to eliminating the overcharge and deep discharge operating states. Moreover, the proposed system controls smoothly the SMES current using the fuzzy rules' system. The superiority and effectiveness of the proposed SMES controller are verified using simulation-based case studies of utility grids with high PV penetration levels. The obtained results show the effective smoothing of fluctuated power and constant bus voltages in the studied microgrid under the proposed controller. In addition, the proposed SMES controller provides superior performance regarding the lifetime and reliability of the SMES systems and microgrid components.

SMES-Based Fuzzy Logic Approach for Enhancing the Reliability of Microgrids Equipped With PV Generators

We have compared the phase synchronization transition of the second-order Kuramoto model on two-dimensional (2D) lattices and on large, synthetic power grid networks, generated from real data. The latter are weighted, hierarchical modular networks. Due to the inertia the synchronization transitions are of first-order type, characterized by fast relaxation and hysteresis by varying the global coupling parameter K. Finite-size scaling analysis shows that there is no real phase transition in the thermodynamic limit, unlike in the mean-field model. The order parameter and its fluctuations depend on the network size without any real singular behavior. In case of power grids the phase synchronization breaks down at lower global couplings, than in case of 2D lattices of the same sizes, but the hysteresis is much narrower or negligible due to the low connectivity of the graphs. The temporal behavior of desynchronization avalanches after a sudden quench to low K values has been followed and duration distributions with power-law tails have been detected. This suggests rare region effects, caused by frozen disorder, resulting in heavy-tailed distributions, even without a self-organization mechanism as a consequence of a catastrophic drop event in the couplings.

Balint Hartmann

Papers

Effects of decreasing synchronous inertia on power system dynamics—Overview of recent experiences and marketisation of services

Cooperation of a Grid-Connected Wind Farm and an Energy Storage Unit—Demonstration of a Simulation Tool

SMES-Based Fuzzy Logic Approach for Enhancing the Reliability of Microgrids Equipped With PV Generators

Heterogeneity effects in power grid network models.

Evaluation of business possibilities of energy storage at commercial and industrial consumers – A case study