Scapulothoracic bursitis contributes to considerable morbidity in some patients with scapular pain. A scapulothoracic bursa injection can induce symptomatic relief; however, blind injections into the scapulothoracic bursa may involve injecting into the subscapularis muscle itself. The aim of this study was to compare the therapeutic effects of intramuscular injections into the subscapularis under ultrasound (US) guidance with those of blind scapulothoracic bursa injections in patients with scapular pain. This study was a single-center, prospective, randomized, single-blinded, controlled clinical trial. Thirty-six patients with suspected scapulothoracic bursitis, who met the inclusion criteria, were recruited between January 2009 and December 2012. We performed three US-guided intramuscular injections into the subscapularis muscle or three blind scapulothoracic bursa injections at 1-week intervals. A visual analogue scale (VAS) and the Rubin scale at baseline and at 1, 2, and 3 weeks after the last injections were examined and again at 3 months after the last injections by a blinded investigator. Adverse effects were monitored. The VAS scores at baseline were 7.7 ± 1.3 and 7.8 ± 1.4 in the intramuscular injection and scapulothoracic bursa injection groups, respectively. Mean VAS scores after the intramuscular injections were 3.8, 2.7, 1.3, and 3.5, and mean VAS scores after scapulothoracic bursa injections were 4.1, 2.4, 1.6, and 2.9 at 1, 2, 3 weeks and at 3 months after the last injections. VAS scores decreased significantly after the injections in each group (p ≤ 0.05). However, no significant difference was observed between intramuscular injection into the subscapularis and the scapulothoracic bursa injection. No serious complications were encountered. In conclusion, injections at the scapulothoracic bursa without US guidance did not exclude the possibility of an effect of steroid on the subscapularis muscle, as both intramuscular injections into the subscapularis and scapulothoracic bursa injections in patients with scapular pain provided equal symptomatic relief, and all patients developed tenderness in their subscapularis muscle.
In order to maintain customer voltage within allowable limit(220±13V), tap operation of SVR(step voltage regulator) installed in primary feeder could be carried out according to the scheduled delay time(30 sec) of SVR. However, the compensation of BESS(battery energy storage system) is being required because the customer voltages during the delay time of SVR have a difficultly to maintain within allowable limit when PV system is interconnected with primary feeder. Therefore, this paper presents modeling of SVR to regulate voltage with the LDC(line drop compensation) method and modeling of BESS to control active and reactive power bi-directionally. And also, this paper proposes the coordination control modeling between BESS and SVR in order to overcome voltage problems in distribution system. From the simulation results based on the modeling with the PSCAD/EMTDC, it is confirmed that proposed modeling is practical tool for voltage regulation analysis in distribution system.
-In order to maintain customer voltages within the allowable limit(220±13V) as much as possible, tap operation strategy of SVR(Step Voltage Regulator) which is located in primary feeder, is widely used for voltage control in the utilities. However, SVR in nature has operation characteristic of the delay time ranging from 30 to 150 sec, and then the compensation of BESS (Battery Energy Storage System) during the delay time is being required because the customer voltages in distribution system may violate the allowable limit during the delay time of SVR. Furthermore, interconnection of PV(Photovoltaic) system could make a difficultly to keep customer voltage within the allowable limit. Therefore, this paper presents an optimal coordination operation algorithm between BESS and SVR based on a conventional LDC (Line Drop Compensation) method which is decided by stochastic approach. Through the modeling of SVR and BESS using the PSCAD/EMTDC, it is confirmed that customer voltages in distribution system can be maintained within the allowable limit.
-This paper deals with the modified modeling of PV system based on the PSCAD/EMTDC and optimal control method of customer voltages in real distribution system interconnected with the photovoltaic (PV) systems. In order to analyze voltage variation characteristics, the specific modeling of PV system which contains the theory of d-q transformation, current-control algorithm and sinusoidal PWM method is being required. However, the conventional modeling of PV system can only perform the modeling of small-scale active power of less than 60 [kW]. Therefore, this paper presents a modified modeling that can perform the large-scale active power of more than 1 [MW]. And also, this paper proposes the optimal operation method of step voltage regulator (SVR) in order to solve the voltage variation problem when the PV systems are interconnected with the distribution feeders. From the simulation results, it is confirmed that this paper is effective tool for voltage analysis in distribution system with PV systems.
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