A robust adaptive load frequency control for micro-grids

The goal of this study is to introduce a novel robust load frequency control (LFC) strategy for micro-grid(s) (MG(s)) in islanded mode operation. Admittedly, power generators in MG(s) cannot supply steady electric power output and sometimes cause unbalance between supply and demand. Battery energy storage system (BESS) is one of the effective solutions to these problems. Due to the high cost of the BESS, a new idea of Vehicle-to-Grid (V2G) is that a battery of Electric-Vehicle (EV) can be applied as a tantamount large-scale BESS in MG(s). As a result, a new robust control strategy for an islanded micro-grid (MG) is introduced that can consider electric vehicles׳ (EV(s)) effect. Moreover, in this paper, a new combination of the General Type II Fuzzy Logic Sets (GT2FLS) and the Modified Harmony Search Algorithm (MHSA) technique is applied for adaptive tuning of proportional-integral (PI) controller. Implementing General Type II Fuzzy Systems is computationally expensive. However, using a recently introduced α-plane representation, GT2FLS can be seen as a composition of several Interval Type II Fuzzy Logic Systems (IT2FLS) with a corresponding level of α for each. Real-data from an offshore wind farm in Sweden and solar radiation data in Aberdeen (United Kingdom) was used in order to examine the performance of the proposed novel controller. A comparison is made between the achieved results of Optimal Fuzzy-PI (OFPI) controller and those of Optimal Interval Type II Fuzzy-PI (IT2FPI) controller, which are of most recent advances in the area at hand. The Simulation results prove the successfulness and effectiveness of the proposed controller.     

An adaptive limited wide area differential protection for power grid with microsources

The operation mode of power grids with intermittent distributed generations (DGs) changes frequently due to the bidirectional power flow. In comparison with the conventional grids, the protection relays in power grids with micro-sources are more difficult to set. To tackle this problem, this paper proposes an extended bus differential protection (EBDP) strategy based on the limited wide area (LWA). In this method, the micro-grids are divided into several protection areas at the core of the bus. The whole protection areas are protected by the wide area current differential relays, which are also configured to protect each component in this protection area. Moreover, the protection areas can be changed adaptively according to the power flow direction. Finally, a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform. The simulation results indicate that the proposed adaptive limited wide area differential protection (LWADP) has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault, and can be widely utilized in larger micro-grids.     

A modified particle swarm optimization algorithm for scheduling renewable generation in a micro-grid under load uncertainty

Renewable Energy Sources (RESs) have many benefits especially when integrated in micro-grids. In this paper, the particle swarm optimization (PSO) algorithm is modified for the optimal power sharing among several RESs such as wind (WT), photovoltaic (PV), and a combined heat and power (CHP) plants within a micro-grid framework. To evaluate the proposed method, first it is utilized to optimally schedule RESs in a micro-grid with the aim of cost minimization without uncertainty. Then, it is implemented under the load uncertainty and the random nature of demand is modeled by the scenario-based stochastic programming. Finally, the proposed algorithm is verified using some benchmark functions. The proposed method is compared with some different Meta-heuristic algorithms and it presents encouraging results in the RESs scheduling and solving benchmark functions.     

Economic viability assessment of sustainable hydrogen production,storage, and utilisation technologies integrated into on- and off-grid micro-grids: A performance comparison of different meta-heuristics

In recent years, there has been considerable interest in the development of zero-emissions, sustainable energy systems utilising the potential of hydrogen energy technologies. However, the improper long-term economic assessment of costs and consequences of such hydrogen-based renewable energy systems has hindered the transition to the so-called hydrogen economy in many cases. One of the main reasons for this is the inefficiency of the optimization techniques employed to estimate the whole-life costs of such systems. Owing to the highly nonlinear and non-convex nature of the life-cycle cost optimization problems of sustainable energy systems using hydrogen as an energy carrier, meta-heuristic optimization techniques must be utilised to solve them. To this end, using a specifically developed artificial intelligence-based micro-grid capacity planning method, this paper examines the performances of twenty meta-heuristics in solving the optimal design problems of three conceptualised hydrogen-based micro-grids, as test-case systems. Accordingly, the obtained numeric simulation results using MATLAB indicate that some of the newly introduced meta-heuristics can play a key role in facilitating the successful, cost-effective development and implementation of hydrogen supply chain models. Notably, the moth-flame optimization algorithm is found capable of reducing the life-cycle costs of micro-grids by up to 6.5% as compared to the dragonfly algorithm.     

An adaptive limited wide area differential protection for power grid with microsources

The operation mode of power grids with intermittent distributed generations (DGs) changes frequently due to the bidirectional power flow. In comparison with the conventional grids, the protection relays in power grids with micro-sources are more difficult to set. To tackle this problem, this paper proposes an extended bus differential protection (EBDP) strategy based on the limited wide area (LWA). In this method, the micro-grids are divided into several protection areas at the core of the bus. The whole protection areas are protected by the wide area current differential relays, which are also configured to protect each component in this protection area. Moreover, the protection areas can be changed adaptively according to the power flow direction. Finally, a micro-grid model with multiple DGs is developed using the PSCAD/EMTDC platform. The simulation results indicate that the proposed adaptive limited wide area differential protection (LWADP) has better performance than the traditional relaying protection in detecting the faulty area in micro-grids and isolating the fault, and can be widely utilized in larger micro-grids.     

State policies for collaborative local renewable integration

New technologies are transforming the US energy sector. Unprecedented opportunities lie ahead for local renewable energy development. Proper system and resource integration is therefore an economic imperative. Technical and economic integration will require policy alignment and collaboration among cities, counties, energy utilities (both gas and electric), and state government. There is also a potentially invaluable role for higher education in support of local planning and integration. State policy interventions in support of collaborative local renewable integration will be a necessary supplement to existing market and regulatory structures.States can affirm fundamental property rights that empower communities and citizens to actively support local climate action and adaptation. State policy can drive the evolution of existing market and regulatory structures to account for local differences and provide increased flexibility for local jurisdictions to address their diverse local resource opportunities and usage profiles.In parallel, states can encourage cities and counties to increase their capacity to take on vital new roles. State energy regulators will need to balance public interest in the economic health of the companies against they regulate against the opportunity to secure important benefits of local clean energy resource development and integration. They will need to create new processes for harmonizing and cross-leveraging progress toward diverse local goals with progress toward over-arching state goals.The key enabling factor will be a culture of collaboration between energy service providers and local governments. Collaborative local renewable integration can be empowered by state action that creates new points of coordination, integration and assistance.Through policy interventions, states can reduce or eliminate barriers to collaborative local renewable integration while capturing opportunities to bring together local government and energy utility capacities and data, plus capacities of universities, non-profit and utility training programs.