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141.
142.
Hirotoshi Kohno Tatsuhito Nakajima Akihiko Yokoyama 《Electrical Engineering in Japan》2000,133(3):35-47
The Unified Power Flow Controller (UPFC) can inject voltage with controllable magnitude and phase angle in series with a transmission line. It can also generate or absorb controllable reactive power. UPFC is expected to be able to damp power system oscillations more effectively than power electronics devices such as SVG and TCSC. In this paper, a control system design of a UPFC for power system damping enhancement based on the eigenvalue control method is proposed. It is made clear that the best design method for the power system damping enhancement is to determine steady‐state values of the UPFC control variables and the control parameters of the UPFC such as gains and time constants simultaneously, because the controllability of UPFC depends on the steady‐state values of UPFC and the power flow condition. The effectiveness of the proposed control system taking into account UPFC inverter ratings is verified by digital time simulation. Furthermore the effects of the input signals to the UPFC controller on small‐signal stability and transient stability enhancement are studied, and it is made clear that UPFC controllers using global information are more effective for power system damping enhancement than those using local information because global information has stronger observability for power system oscillations than local information. © 2000 Scripta Technica, Electr Eng Jpn, 133(3): 35–47, 2000 相似文献
143.
统一潮流控制器(UPFC)应用于潮流调控时,计及UPFC调控参数的交流潮流计算是非凸、非线性问题,且多台装置间的非线性交叉耦合特性也会直接影响优化配置方案。为此,基于UPFC的潮流调控特性,构建了计及UPFC的松弛型交流潮流二阶锥规划模型;计及风电的不确定性,协同考虑UPFC的规划和电力系统的调度问题,建立了计及UPFC最优配置的电力系统鲁棒协同优化模型,并采用列和约束生成算法进行求解。以IEEE RTS-24节点系统为算例进行仿真分析,结果表明所提协同优化策略有效提升了UPFC配置方案的适应性,提高了系统运行经济性和风电消纳能力,增强了系统运行调控的灵活性。 相似文献
144.
This paper presents a wavelet fuzzy based protection scheme for a double line transmission system with unified power flow controller. The protection scheme makes use of current signals at both the ends of transmission line which are synchronized with the help of global position system clock. A wavelet based multiresolution analysis is used to find the detailed coefficients of these signals which are utilized to calculate fault index. These fault indexes are compared with a threshold value to detect and classify faults on transmission system. The approximate decomposition of the current signals is utilized to locate the fault using Fuzzy logic from their respective terminals. The proposed algorithm has been tested successfully for various faults at different locations. 相似文献
145.
In this document, the Firefly Algorithm (FA) and Cuckoo Search (CS) algorithm based on optimal location and the capacity of UPFC to improve the dynamic stability of the power system are proposed. The novelty of the proposed method is exemplified in the improved searching ability, random reduction and reduced complexity. In this regard, the generator fault affects the system dynamic stability constraints such as voltage, power loss, real and reactive power. Here, the FA technique optimizes the maximum power loss line as the suitable location of the UPFC. The affected location parameters and dynamic stability constraints are restored into secure limits using the optimum capacity of the UPFC, which in turn, has been optimized with reduced cost by using the CS algorithm. The attained capacity of the UPFC has been located in the affected location and the power flow of the system analyzed. The proposed method is implemented in the MATLAB/Simulink platform and tested under IEEE 30 and IEEE 14 standard bench mark system. The proposed method performance is evaluated by comparison with those of different techniques such as ABC-GSA, GSA-Bat, Bat-FA and CS algorithms. The comparison results invariably prove the effectiveness of the proposed method and confirm its potential to solve the related problems. 相似文献
146.
ABSTRACT This paper presents a novel procedure to determine the maximum regulating capability of a unified power flow controller (UPFC) by using optimal multiplier power flow. The capabilities of flexible ac transmission systems (FACTS) equipment are not only constrained by their thermal limits and the steady-state security limits, but also limited by their feasibility limits. After the detailed analyses have been made on the use of optimal multiplier u as a new predictor to estimate the boundary point of the feasibility region, an algorithm for deteiTnirung the UPFC regulating capability is proposed. The approach is then compared with minimum singular value decomposition on the IEEE 30 bus system. The results clearly demonstrate the effectiveness of the proposed approach. 相似文献
147.
随着串联电容补偿输电的推广应用,中国电力系统面临着严峻的次同步谐振(SSR)问题。针对SSR问题,文中基于采用电流控制模式的统一潮流控制器(UPFC),提出了一种UPFC附加阻尼控制抑制SSR的方法;首先选择了附加阻尼控制信号接入UPFC控制器的位置,然后设计了UPFC附加次同步阻尼控制器(SSDC),并推导了其抑制系统SSR的机理,且所设计的SSDC采用了模态分离控制以达到抑制多模态SSR的目的。最后,综合利用复转矩系数和时域仿真的方法,对所设计的UPFC装置SSDC抑制SSR的有效性进行了分析和仿真。结果表明,所设计的SSDC在有效抑制SSR的同时,不会影响系统和UPFC装置的正常运行。 相似文献
148.
149.
A.M. El-Zonkoly H. Desouki 《International Journal of Electrical Power & Energy Systems》2011,33(8):1368-1374
Distance protection of transmission lines including advanced flexible AC transmission system (FACTS) devices has been a very challenging task. FACTS devices of interest in this paper are static synchronous series compensators (SSSC) and unified power flow controller (UPFC). In this paper, a new algorithm is proposed to detect and classify the fault and identify the fault position in a transmission line with respect to a FACTS device placed in the midpoint of the transmission line. Discrete wavelet transformation and wavelet entropy calculations are used to analyze during fault current and voltage signals of the compensated transmission line. The proposed algorithm is very simple and accurate in fault detection and classification. A variety of fault cases and simulation results are introduced to show the effectiveness of such algorithm. 相似文献
150.