Distributed generation (DG) may bring about reliability degradation, instead of reliability enhancement, due to recloser-fuse miscoordination. For the prevention of this reliability degradation, this paper proposes a method to find the threshold value of the DG capacity, beyond which recloser-fuse coordination is lost. Mathematical equations for protective devices are used to set up the protection settings and calculate the threshold value. Three reliability indices-SAIFI, SAIDI, and ENS-are evaluated and compared with the study cases in the reliability test system RBTS bus 2. The results show that the proposed method is effective to prevent the deterioration of system reliability. In addition, a simple modification to the protection system is presented as a preliminary solution.

memberWith the increased number of installations of distributed photovoltaic (PV) systems within electricity distribution systems, power flow analysis is required to handle multiple PV systems. At present, PV systems are equipped with a local control function (LCF). The conventional algorithm is then applied for power flow analysis with the LCF of each PV system, where the power output of LCF of each PV system is calculated and used in the power flow calculation. The conventional algorithm is terminated when the voltage at each iteration of the power flow algorithm is converged. However, the conventional algorithm inevitably requires a lengthy calculation. This paper proposes a power flow algorithm that applies the Newton-Raphson technique to handle multiple PV systems with an LCF for a faster calculation. The LCF is approximated to have a continuous characteristic. The developed power flow algorithm can be used for a three-phase unbalanced distribution system and its effectiveness was demonstrated in a modified 19-node distribution system. coordination of a P(U) and Q(U) LCF [1], or coordination of a P(U) and Q(P) LCF [4].Due to the application of the conventional algorithm, the abovementioned studies [1-4] required a lengthy calculation. In addition, consideration of the three-phase balanced distribution system [1-3] might be inaccurate because the loading of any LV distribution system is inherently unbalanced due to many unequal singlephase loads and single-phase PV systems and the non-symmetrical conductor spacing of three-phase overhead line segments. The connection of only three-phase PV systems [1-3] is inaccurate because LV distribution systems are typically not only connected by three-phase PV systems but also single-phase PV systems. The operation of only the P(U) LCF [2] causes less real power generation from PV systems because of the lack of reactive power support, while the operation of only a Q(U) LCF [3] cannot mitigate the voltage rise effectively when the real power generation from PV systems increases.The coordination between P(U) and Q(U) or between P(U) and Q(P) LCFs [1,4] causes a greater real power generation from PV systems, because of the reactive power support, and so it causes an effective voltage-rise mitigation. This paper considers the coordination between the P(U) and Q(U) LCF because the power output from PV systems will depend on the voltage at the connection point and the developed PFA can be applied appropriately. The developed PFA analyzes power flow with a P(U) and Q(U) LCF, which were developed to have a continuous characteristic by applying the Newton-Raphson method. As a result, the calculation is faster. . His interests include renewable energy, distributed generation, power system planning and operation, electricity market, and smart grid development.

No abstract

No abstract

No abstract