Sahar Kaddah

Assessment of the economic penetration levels of photovoltaic panels, wind turbine generators and storage batteries

Abstract Assessment of the economic penetration levels of photovoltaic panels (PVPs), wind turbine generators (WTGs) and storage batteries (SBs) into conventional generation systems is the main target of this article. The economic penetration level is that which achieves the maximum permissible reduction in the kWh cost and a certain value of loss-of-load expectation (LOLE) or expected unserved energy (EUE). To carry out this target, the following steps were performed: proposal of an operation strategy for the studied combined (hybrid) system; introduction of the analysis of the LOLE and EUE; and deduction of the mathematical models for estimating the fuel saving, load carrying capability, levelized annual profit and reduction in the kWh cost. The LOLE and EUE of the studied hybrid system were computed for different penetration levels of PVPs, WTGs and SBs. The reductions obtained in the kWh cost were also recorded. The different penetration levels that achieve a specific value of the LOLE or EUE were determined. The economic level was evaluated on the basis of the reduction obtained in the kWh cost.

Impact of wind farms on contingent power system voltage stability

With the global trend towards deregulation in the power system industry, the volume and the complexity of the contingency analysis results in the daily operation and system studies have been increasing. This paper discusses the impact of wind turbine generating units (WTGUs) on power system voltage stability. A probabilistic voltage stability algorithm is developed via power flow analysis where these units are modeled as P-Q bus(es) by detecting the collapse point on the Q-V curves. The developed algorithm also facilitates the computation of both the real and reactive power output of the fixed speed pitch regulated wind turbine at a specific site, wind turbine characteristics, wind speed and terminal voltage. The probabilistic nature of wind is considered by introducing the expected voltage stability margin as an index that combines both of the voltage stability and the wind distribution in one index. The proposed algorithm is implemented and applied on the IEEE 26-bus, voltage stability margin (VSM), and expected voltage stability margin (EVSM) are calculated at each wind speed. The accumulation of the EVSM over a specific period can be considered as the system voltage stability margin which is a single value that can be compared with the voltage stability margin of the all-conventional power system. Finally a contingency analysis for wind power through severe outage cases relevant to conventional power system is investigated.

Influence of Distributed Generation on Distribution Networks During Faults

Abstract Distributed generation is playing an increasingly important and positive role in decreasing network losses, reducing electricity prices, maintaining environmental and economical benefits, reducing the investment in generation capacity, and delaying the upgrade of the transmission system. Therefore, researchers have become interested with distributed generation and its connection with the main power network. But before connecting these resources with the main grid on the low-voltage level, the worst-case scenario that could occur must be analyzed first. This article introduces a procedure to study the effect of the distributed generation units on distribution systems during short-circuit periods. This effect is measured in terms of fault current, transient time, voltage total harmonic distortion, voltage sag, and voltage swell. The main objective of this study is to study the influence of distributed generation on distribution systems so the maximum distributed generation penetration that can be adopted in a distribution system without degrading the system performance is determined. A general purpose alternative transients program version of the electromagnetic transient program is used to accomplish the above goals. The proposed method is tested on IEEE 13-node test feeder distribution system to demonstrate its performance.

Maximum power control of hybrid wind-diesel-storage system

Optimum wind energy extraction is a very important economical target. This paper is concerned with the development of a robust controller for the wind turbines in hybrid wind-diesel storage system (HWDSS). The proposed algorithm, which is based on fuzzy linear matrix equalities (FLME), maximizes the power coefficient for a fixed pitch. Moreover, it reduces the voltage ripple and stabilizes the system over a wide range of wind speed variations. The control scheme is tested for different profiles of wind speed pattern and provides satisfactory results.

Economic Power Dispatch with Emission Constraint and Valve Point Loading Effect Using Moth Flame Optimization Algorithm

Economic dispatch (ED) is an important optimization task in power system which involves determination of the optimal combination of power outputs for all generating units which will minimize the total fuel cost while satisfying load constraints. There are three criteria in solving the economic load dispatch problem. They are minimizing the total generator operating cost, total emission cost and multi-objective (cost and emission). This paper proposes Moth Flam Optimization (MFO) algorithm for solving the economic dispatch problem with valve point effects and emissions. It determines the optimal generation schedule of generating units by minimizing three criteria. Two test systems consisting of 6 generating units and isolated microgrid have been used to illustrate the effectiveness of the proposed MFO method. The results obtained from MFO is compared with different algorithms. The results show better global convergence and also gives good optimum solution by reducing system generation cost and emission cost.