Severe Voltage fluctuations at different points of the network are the main concerns of the widespread low-Voltage electrical energy distribution networks. In particular, small industrial loads and rural consumers in remote geographical areas, which are fed by long lines, always experience great Voltage drops. The use of common distribution transformers equipped with off-load tap changers has not been effective in solving this problem due to issues such as lack of access to all network points for operators, the need to de-energize the line during tap change, and the successive and unpredictable load changes. Therefore, the use of transformers with automatic Voltage adjustment at different points of distribution networks has attracted much attention. The present research aimed to implement a simple solid-state Voltage Regulator (SSVR) in the low power range to automatically eliminate severe Voltage fluctuations. In this research, a solid-state Voltage Regulator with a rated power of 5 KVA was designed and built to automatically compensate for the Voltage of a small group of home customers (who have a severe Voltage drop due to the distance from the distribution post). The results of the measurements showed that this equipment can limit the Voltage changes to 220±3%, while it does not affect the power quality. In addition, various hardware and software protections were designed for the device built against network disturbances and abnormal consumer functions.

Electricity distribution network delivers Voltage 220V to single phase customers. In weak distribution system, the length of feeders is long so the end of feeders is faced with excessive Voltage drop. Compensating for this Voltage drop by constructing medium Voltage power system and installing new distribution substations is not cost effective. Especially in rural areas where the prospect of development and increase in subscribers is unlikely. Therefore, other flexible and low-cost solutions should be considered. In this research, to compensate for Voltage drop, a small group of home subscribers who have Voltage drop due to their distance from the distribution substation, a semi-industrial model of solid-state Voltage Regulator is designed and manufactured. In this structure, dry autotransformers with nominal power of 15KVA will be used as single-phase (or three-phase). The low-Voltage autotransformer taps are changed by the use of triac semiconductor switches with Voltage closed-loop control. To show the efficiency of this method, a 500VA laboratory sample was made using 12 triacs with 40A rated current, from which successful results were obtained. The measurement results show that this equipment can limit the Voltage changes to the range of 0.95 to 1.05 of the nominal value while also not affecting the quality of power. The semi-industrial version of this Voltage Regulator has been manufactured and successfully tested, in which appropriate protection functions are embedded for operational use in power systems.

This paper presents a low quiescent current low-dropout Voltage Regulator (LDO) with controlled pass transistor which can work either with on-chip or off-chip output capacitor. The pass transistor of the proposed LDO has lower width in low load condition and has higher width for moderate to heavy load current and the LDO topology transforms between a two-stage structure in low load current and a three-stage one in moderate to high load current. The proposed LDO topology is designed and simulated in HSPICE in a 0.35 mm CMOS process to provide a 2.8 V output Voltage for a 3 V input Voltage and is capable to deliver a stable output current in the range of 0-100 mA to the load with a 100 pF on-chip output capacitor while its quiescent current is only 7.5 mA. Without using the adaptively-controlled pass transistor, the maximum output variations of the LDO to the 0-100 mA load transient is 540 mV and its settling time is 11 ms, while using this technique decreases the output Voltage variations and settling time to 280 mV and 6.5 ms, respectively.

Distribution systems management is becoming an increasingly complicated issue due to the introduction of new technologies, new energy trading strategies, and new deregulated environment. In the new deregulated energy market and considering the incentives coming from the technical and economical fields, it is reasonable to consider Distributed Generation (DG) as a viable option to solve the lacking electric power supply problem. This paper presents a mathematical distribution system planning model considering three planning options to system expansion and to meet the load growth requirements with a reasonable price as well as the system power quality problems. DG is introduced as an attractive planning option in competition with Voltage Regulator devices and Interruptible load. In the mathematical model, the objective function includes investment costs, which are evaluated as annualized total cost, plus the total running cost as well as the cost of curtailed loads and losses. This model identifies the optimal type, size, and location of the planning options. This paper also studies the fluctuation of the load and electricity market price versus time period, and the effect of DG placement on system improvement. To solve the proposed mathematical planning model a new software package by interfacing MATLAB and GAMS is developed. This package enables one to solve large extent distribution system planning program visually and very fast. The proposed methodology is tested on the case of the well-known IEEE 30-bus test system. 

This paper presents a low dropout Voltage Regulator, with the specifications suitable for hearing aid devices. The proposed LDO occupies very less area on chip and provides an excellent transient response. A novel Voltage spike suppressor block is employed in the LDO architecture which reduces undershoot and overshoot of the output Voltage during the abrupt load transition. It introduces a secondary negative feedback loop whose delay is lesser than the main loop and also steers the quiescent current to output node when required. This not only improves overall current efficiency but also reduces the on chip capacitance. The proposed LDO is laid out in 180 nm standard CMOS technology and post layout simulations are carried out. The LDO produces 0.9 V output when a minimum supply Voltage of 1 V is applied. A maximum load of 0.5 mA can be driven by the Regulator. The LDO exhibits 4.4 mV/V and 800 μV/mA line and load regulations respectively. When subjected to a step load change, an undershoot of 20.34 mV and an overshoot of 30.28 mV are recorded. For proper operation of the LDO, it requires only 4.5 pF on-chip capacitance.

Controller design and optimization problems, with more than one objective, are referred as multiple objectives or multiple attributed problems. In this paper, a novel method is proposed for designing optimum PID controller that is called genetic multiple attributed decision making method (GMADM). This method is newer than the previous methods and in this paper some options are considered that have not been considered in previous paper for simplicity. The proposed PID controller is applied on the automatic Voltage Regulator (AVR). An automatic Voltage Regulator system is the main part of a generator because this system keeps the output Voltage in constant level. The simulation results of automatic Voltage Regulator system are compared with conventional multiobjective algorithm, known as multiobjective genetic algorithm (MOGA).The simulation results of automatic Voltage Regulator system show that GMADM method is better than MOGA and the number of optimum solutions of the proposed method is greater than the other one.

One of the essential pieces of equipment in the power system is the Automatic Voltage Regulator (AVR) or synchronous generator excitation. The system's goal is to maintain the terminal Voltage of the synchronous generator at the desired level. AVR is inherently uncertain. Hence, the proposed controller should be able to handle the problem. In this paper, Fractional Order Fuzzy PID (FOFPID) controller has been employed to control the system. To enhance the controller's performance, the Grasshopper Optimization Algorithm (GOA) is used to tune the controller's parameters. Unlike other methods, the FOFPID controller gains are not constant and alter in different operating conditions. The robustness of the controller has been investigated, and the comparative results show that the proposed controller has a better performance against other methods.