Abstract
This paper proposes a distributed economic power dispatch (EPD) and bus voltage control solution for droop-controlled DC microgrids. For the proposed solution, a local power controller and a local voltage controller are added for each distributed generator (DG) to overcome the limitations of the conventional droop control. The power controller generates the first voltage correction term by comparing the local output power of DG with the reference instruction generated by the proposed distributed EPD algorithm, and thus, it can reduce the operation cost of the microgrid by optimally sharing the load demand among all the participating DGs. The voltage controller generates the second voltage correction term by comparing the nominal DC bus voltage value with the average bus voltage generated by the proposed distributed average bus voltage observation (ABVO) algorithm, and thus, it can realize the global bus voltage regulation of the DC microgrid. In contrast with conventional solutions, the control solution can distribute the computational and communication burdens among all the DGs working in parallel, which is more flexible, scalable, and robust against single-point failure. The effectiveness of the proposed control solution is demonstrated through simulation studies.
Highlights
The microgrid concept is receiving considerable interest, as it can integrate a large amount of distributed generator (DG) into the power grid in a more environmentally-friendly and reliable way [1]
These two correction terms are generated based on the distributed consensus-based economic power dispatch (EPD) algorithm and average bus voltage observation algorithm proposed in this paper
Δvi,2 = (k p2 + kSi2 )(vnom − v) where i represents the DG index, δvi,1 and δvi,2 represent the first and the second voltage correction terms, respectively, k p1, k i1, k p2, k i2 are the parameters of PI controllers, Pre f i is the reference value of power control demands generated by the proposed EPD algorithm (Section 3), Pi is the locally-measured active power, vnom represents the preset value of nominal DC bus voltage, and vrepresents the average bus voltage generated by the proposed average bus voltage observation (ABVO) algorithm (Section 3)
Summary
The microgrid concept is receiving considerable interest, as it can integrate a large amount of DGs into the power grid in a more environmentally-friendly and reliable way [1]. In most of the distributed EPD algorithms [17,19,20,22], the load nodes and the uncontrollable generator nodes need to be designed with the capability of communication, since their information is required for the power imbalance estimation, which increases the complexity and costs of the system. A distributed optimal bus voltage control for droop-controlled DC microgrids is proposed. The proposed method is augmented with two additional correction terms to provide economic load sharing and global bus voltage regulation, respectively. These two correction terms are generated based on the distributed consensus-based EPD algorithm and average bus voltage observation algorithm proposed in this paper.
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