The role of reactive power can be understood as it affects voltage stability, power factor and losses in a power system. Now a day's quality of electrical power in a network is becoming a major concern which must be examined in order to achieve a reliable electrical power system. To realize the goal of qualitative and reliable electrical power system reactive power compensation is one of the solutions. This paper reviews different technology used in reactive power compensation such as synchronous condenser, static VAR compensator, capacitor bank, series compensator and shunt reactor, comparison between them, source of reactive power and different optimization techniques. After observation and conclusion is made the most useful technology and optimization techniques is recommended for future works.

Power systems are very large and complex, it can be influenced by many unexpected events this makes Power system optimization problems difficult to solve, hence methods for solving these problems ought to be, an active research topic. This review presents an overview of important mathematical optimization methods those are Unconstrained optimization approaches Nonlinear programming (NLP), Linear programming (LP), Quadratic programming (QP), Generalized reduced gradient method, Newton method, Network flow programming (NFP), Mixed-integer programming (MIP), Interior point (IP) methods and Artificial intelligence (AI) techniques such as Artificial Neural Network (ANN), fuzzy logic,Genetic Algorithm (GA), Particle Swarm Optimization (PSO),Tabu Search (TS) algorithm, etc. and Hybrid artificial intelligent techniques are discussed. And also applications of optimization techniques have been discussed. Finally classification, application area, observation, conclusion, and recommendation for future research work will be forwarded.

Economic dispatch problem is one of the fundamental problems in power system as proved by many researchers. Since working on smart grid at lowest cost with high efficiency is a big challenge. Solving this problem will be active research topic for future. In the current paper, we are going to show detailed description of progress on economic dispatch, centralized and decentralized algorithm, and demand side management, classical and modern techniques by looking for the way and key factors in their progress. Plenty of work is available on demand side management, using different alternatives as it is related to optimization of generation, and system load cost models. With this scope of review work, the perspective of the economic dispatch problem in the smart grid has been investigated. This paper revises different author's work related to the economic dispatch problem and gives an insight to future work.

Generators are the majority source of commercial electrical energy and the most essential and expensive elements in power industry since, it is difficult to replace. It need to protect either by using electrical or mechanical protection devices before any failure is happen on those equipment's since, protecting equipment's from any failure can improve reliability of the system, minimize operating cost and minimize energy or power loss. Under this paper different types of fault on generator such as stator fault, rotor fault and abnormal condition of generator, protection techniques based on (Change in load current, Stator temperature and resistance and Rotor speed) for those faults on generator, protection devices (relay, instrument transformer, circuit breaker and so on), optimization techniques are discussed in detailed and observation and gap seen from the paper, conclusion and recommendation for future researchers are indicated .

In order to achieve the therapeutic purpose, the choice of the most suitable delivery route is of indisputable importance. Therefore, certain factors must be taken into consideration when delivering a active substance, namely its own properties, the disease to be diagnosed and the desired beneficial time. The active substances can be directly to the target tissue or organ or can be delivered by systemic routes.