Power Electronics Loads Considering Response Cost
Nowadays, microgrid has received worldwide attention, where a few DG units and loads are clustered together [1]. It is a good choice for power system to improve the reliability and power quality. Microgrid operation is highly flexible, it therefore can operate freely between the grid-connected mode and islanded mode [2], [3]. It is well known that operation stability and reliability of power system is highly depended on balance between the supply and demand in real time. This is a big challenge for microgrid since both power generators and loads could change rapidly and unexpectedly due to many reasons, such as DGs capacity limitation, output power fluctuation, line fault and sudden load change [4], [5].
Keeping large power reserve can solve this problem. In [6], ESS are considered in the microgrid construction and applied to help maintain the supply and demand balance. Although, it can maintain the microgrid stable, it is not ideal mothed due to the high price of the ESS. On the other hand, the demand side (load) response is one of the available and cheaper method to solve the supply and demand imbalance problem in microgrid [7]. Demand Response can be defined as the end users change their consumption models to response the power grid operation.
There are many researches on the demand response program used in the utility grid, which can generally be classified as the price-based programs and incentive-based programs [7]-[9], as shown in Fig. 1. The demand response programs are usually integrated to the power network management system. Although the centralized demand response programs are generally more accurate, they usually need expensive and fast communication links which may not be economical for islanded microgrid. While, the response program reliability is highly dependent on the communication. The communication or the central controller fault may introduce the response method failure. Thus, there is a great interest in decentralized response scheme.
In [10], a decentralized load control of was proposed to introduce the loads to participate in supply and demand balance of the islanded microgrid. It makes the FPELs regulate their power consumption in proportion to their power capacities only using local measurement. However, this scheme does not consider the response cost of the loads involved. It will lead to higher response cost which will introduce additional operation cost for islanded microgrid.
To address the concern illustrated above, an autonomous control of flexible loads considering response cost scheme has been proposed in this paper. The proposed schemes use the response cost of the FPELs to achieve different dispatch for various FPELs to participate in the supply and demand balance. It forces the lower response cost FEPL to automatically reduce more power consumption in order to satisfy the supply and demand balance. The overall response cost and the communication links, therefore, will be saved when compared with the traditional load response schemes. Simulation results have verified the effectiveness of the proposed control scheme.
An autonomous control of FPELs considering response cost scheme has been proposed in this paper. Unlike the traditional scheme which consider the response capacities, the proposed control scheme arrived at a better balance between load response capacities and response costs. It makes the lower costed FPEL to reduce more power consumption to participate in the supply and demand balance. Thus, it can reduce the total response cost for the microgrid and save the investments of the ESS and communication system. The finding has been verified via simulation results. View more
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