State estimation operation depends on the measurement numbers, types and locations. Therefore, the adoption of an efficient placement method for selecting the required numbers of meters and their location is an essential process for power systems monitoring. In fact, the Phasor measurement Unit (PMU) is, currently, one of the most efficient devices for measuring real-time electrical quantities. Consequently, this paper aims to present the main categories for PMUs placement strategies according to the objectives of PMUs employment. The PMUs placement strategy should take into consideration main factors that required for enhancing the performance of a state estimation process such as reliability, accuracy and the special requirements of the modern distribution grid. A review of literatures that address PMUs placement methods is presented in this paper in addition to suggestions for developing the PMUs placement methods to be more feasible for modern power networks.

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One of the challenges facing investment in photovoltaic (PV) energy is the accumulation of dust on the surface of the PV panels due to frequent dust storms in many countries, including Iraq. Surface dust particles reduce solar irradiance which declining the electrical performance of the PV solar systems. Therefore, this paper proposes an experimental study to analyze and evaluate the power efficiency of a PV system installed in Baghdad city, Iraq. The performance of dusty solar PV array is compared with that of the clean array of the same PV system. The clean solar array is equipped with an automatic-sprayer cleaning system that is powered by the PV system. The automatic cleaning system utilized in the test system reduces human effort by cleaning the PV array using closed-cycle water with low energy consumption (less than 10 Wh). The PV array under test is part of a 15 kW grid-tied PV system. The experimental results show significant improvement in the performance parameters of efficiency, performance ratio, and the energy gain compared to the clean array. Furthermore, the experimental study contributes to a reduction in CO2 emission, which is substantial for the Iraqi environment that suffers from predominate fossil-fuel power plants.

State estimation (SE) is based on an iterative process for solving weighted least squares (WLS) via the so‐called normal equations (NE). This process is prone to numerical instability and may lead to an ill‐conditioned state estimator in many cases. Although several methods have been proposed in the past to deal with the ill‐conditioning problem in high‐voltage transmission systems, the SE stability of low‐voltage distribution systems remains a challenge due to fewer measurements and high R/X ratios. This paper highlights the main reasons for the ill‐conditioning problem and focuses on the impact of the R/X ratio of the distribution systems. NE‐based SE uses a comparatively simple algorithm with much lower storage size. Hence, this paper proposes a regularized version of the WLS state estimator to solve the problem of ill‐conditioning using an adjustable regularization parameter. Simulation results on U.K. 18‐bus and radial 33‐bus distribution systems show improved performance in terms of reducing the computational complexity, measurements redundancy, the impact of high R/X ratios and improving the accuracy and numerical stability of the SE solution. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The detection of potential voltage collapse in power systems is essential to maintain the voltage stability in heavy load demand. This paper proposes a method to detect weak buses in power systems using two stability indices: the voltage stability margin factor (dS/dY) and the voltage collapse prediction index (VCPI). Hence, the paper aims to improve the voltage stability of Iraqi transmission grid by allocating FACTS devices in the optimal locations and optimal sizes. Two types of FACTS are used in this paper which are Thyristor controlled series compensator (TCSC) and static var compensator (SVC). The objective function of the problem is fitted using particle swarm optimization (PSO). The proposed method is verified using simulation test on Diyala-132 kV network which is a part of the Iraqi power system. The results observed that improvement the voltage stability margin, the voltage profile of Diyala-132 kV is increased and the power losses is decreased.