By consulting various worldwide definitions of microgrids and distributed energy, this study presents a microgrid-structured multi-agent system and uses Matlab/Simulink to construct a circuit with microgrid features, which enables the changes in each electrical source and load in the microgrid to be monitored and controlled. This multi-agent system adheres to the Java Agent Development Framework (JADE) platform specifications of the Foundation for Intelligent Physical Agents (FIPA), facilitating communication, information transfers, and the receipt of real-time information regarding the microgrid and each component in the microgrid. Furthermore, the real-time state in the microgrid can be correspondingly controlled, achieving the most efficient real-time monitoring and control for electrical sources and load management in the microgrid.
Traditionally, interconnection standards avoid islanding operation of distributed generation, DG, due to the concerns of equipment failure and safety issues. However, in some cases, allowing of islanding of DG connected to radial subtransmission system could improve the system reliability and decrease outage cost during power outage or schedule maintenance. In order to perform intentional islanding appropriately, this paper presents the impact study on DG connected to radial subtransmission system. Both steady-state and dynamic studies are performed to show how to arrange DG and electric power system for the intentional islanding on the specific case.
MMP-7 and cathepsins B and V are involved in the generation of endostatin by HLE cells. Facilitating endostatin generation may be a novel physiological function of the cornea-specific cathepsin V.
Taiwan's power system is isolated and not supported by other interconnected systems. Consequently, the system frequency immediately reflects changes in the system loads. Pumped storage units are crucial for controlling power frequency. These units provide main or auxiliary capacities, reducing the allocation of frequency-regulating reserve (FRR) and further reducing generation costs in system operations. Taiwan's Longmen Nuclear Power Plant is set to be converted for commercial operations, which will significantly alter the spinning reserves in the power system. Thus, this study proposes a safe and economic pumped storage unit dispatch strategy. This strategy is used to determine the optimal FRR capacity and 1-min recovery frequency in a generator failure occurrence at the Longmen Power Plant. In addition, this study considered transmission capacity constraints and conducted power flow analysis of the power systems in Northern, Central, and Southern Taiwan. The results indicated that, in the event of a failure at Longmen Power Plant, the proposed strategy can not only recover the system frequency to an acceptable range to prevent underfrequency load-shedding, but can also mitigate transmission line overloading.
When large amounts of wind power and solar photovoltaic (PV) power are integrated into an independent power grid, the intermittent renewable energy destabilizes power output. Therefore, this study explored the unit commitment (UC) optimization problem; the ramp rate was applied to solve problems with 30 and 10 min of power shortage. The data of actual unit parameters were provided by the Taiwan Power Company. The advanced priority list method was used together with a combination of a generalized Lagrangian relaxation algorithm and a random feasible directions algorithm to solve a large-scale nonlinear mixed-integer programming UC problem to avoid local and infeasible solutions. The results showed that the proposed algorithm was superior to improved particle swarm optimization (IPSO) and simulated annealing (SA) in terms of the minimization of computation time and power generation cost. The proposed method and UC results can be effective information for unit dispatch by power companies to reduce the investment costs of power grids and the possibility of renewable energy being disconnected from the power system. Thus, the proposed method can increase the flexibility of unit dispatch and the proportion of renewable energy in power generation. Appl. Sci. 2019, 9, 421 2 of 14 solar PV and wind power generation, respectively. The short-term goal comprised a total installed capacity of PV of 1520 MW and cumulative installed capacities of onshore and offshore wind power of 814 and 520 MW, respectively [2].In the traditional unit commitment (UC) problem, the startup and shutdown times of various units and the power output within a dispatch time period of 1 day to 1 week or even 1 month to 1 season are planned according to the system load to achieve the lowest operating cost. In addition, with the load requirement being satisfied, the traditional unit commitment problem ensures that the criteria for the operation of each unit can be met. These criteria include the upper and lower limits of power output for each unit, the ramp rates of the units, and the balance between the supply of and demand for electricity. However, because of the intermittent characteristic of renewable energy, the power output may substantially decrease or increase within a few minutes due to weather events (such as an eclipse, no wind, or strong wind). Such circumstances are typically managed by using pre-established spinning reserves and storage systems [3]. However, all these methods require additional costs and are unable to effectively use renewable energy.Some studies on the ramp rate of power generating units after the integration of renewable energy into the system are described as follows. Correa-Posada et al. used a dynamic ramping model, namely mixed-integer linear programming, which considered the flexibility of ramping limits to reduce the dynamic errors caused during ramping [4]. Ding and Bie used the IEEE 118 bus as an example; the Lagrangian relaxation method was integrated with the diagonal quadratic approximation method to solve t...
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