An D. T Le

Optimal Distributed Generation Parameters for Reducing Losses with Economic Consideration

Distributed generation (DG) represents a reliable option for solving current major problems of distribution companies, such as load growth, overloaded lines, quality of supply and reliability. Moreover, it has been proven that the additional benefits brought by DG could be substantial if properly used. This paper addresses the issue of optimizing DG planning in term of DG size and location to reduce the amount of line losses in the distribution networks. The optimization methodology, which is based on the sequential quadratic programming (SQP) algorithm, firstly assesses the compatibility of different generation schemes upon the level of power loss reduction and DG cost. The solutions obtained are finally validated with the constraints of maximum number and size of DG, as well as voltage violation and DG penetration. The proposed method is tested on IEEE 33 bus system, proving that the technique is effective and applicable.

A Coordinated Voltage Control Approach for Coordination of OLTC, Voltage Regulator, and DG to Regulate Voltage in a Distribution Feeder

Integration of small-scale electricity generators, known as Distributed Generation (DG), into the distribution networks has become increasingly popular at the present. This tendency together with the falling price of synchronous-type generator has potential to give the DG a better chance in participating in the voltage regulation process together with other devices already available in the system. The voltage control issue turns out to be a very challenging problem for the distribution engineers since existing control coordination schemes would need to be reconsidered to take into account the DG operation. In this paper, we propose a control coordination technique, which is able to utilize the ability of the DG as a voltage regulator, and at the same time minimizes interaction with other active devices, such as On-load Tap Changing Transformer (OLTC) and voltage regulator. The technique has been developed based on the concept of control zone, Line Drop Compensation (LDC), as well as the choice of controllers parameters. Simulations carried out on an Australian system show that the technique is suitable and flexible for any system with multiple regulating devices including DG.

Maximising Voltage Support in Distribution Systems by Distributed Generation

Rapidly increasing in the demand of electricity along with recently advances in distributed generation (DG) technologies have sparked a new interest in utilisation of DG sources. However, there are a number of technical issues regarding to the installation of DG, since DG connection significantly affects existing network configuration and operation, especially for system with high level of DG penetration. To achieve maximum voltage support from DG utilisation, methodologies related to DG placement and DG operation are developed in this paper. Technique to optimise voltage improvement by effectively injecting active and reactive power of DG is developed based on voltage sensitivity of lines. An index has been developed to obtain optimal or near optimal placement of DG for maximum voltage improvement in a distribution feeder. Simulation studies are conducted on 16-bus, 32-bus and 69-bus radial test systems to verify the developed techniques and results are reported.

Control Strategy of Distributed Generation for Voltage Support in Distribution Systems

Voltage problem is always a critical issue in operating a distribution system. The uncertainties of load distribution and variation have introduced a great complexity to the task of maintaining system voltage within the permitted range. In this paper, small-scale generator, known as distributed generation (DG), is employed in the system and acting as a voltage regulator. The output of DG is controlled in such a way that acceptable level of electrical supply quality is achieved with a reasonable operating cost. The DG controller is tested with a non-uniformly varying load on the time domain basis. Simulations have been conducted with both short term (few hundred seconds) and long term (weekly) load data to validate the proposed control technique. Results have proved that the system is well functioning not only technically but also economically.

An Algebraic Approach for Determination of DG Parameters to Support Voltage Profiles in Radial Distribution Networks

Rapidly increasing electricity demands and capacity shortage of transmission and distribution facilities are the main driving forces for the growth of Distributed Generation (DG) integration in power grids. One of the reasons for choosing a DG is its ability to support voltage in a distribution system. Selection of effective DG characteristics and DG parameters is a significant concern of distribution system planners to obtain maximum potential benefits from the DG unit. This paper addresses the issue of improving the network voltage profile in distribution systems by installing a DG of the most suitable size, at a suitable location. An analytical approach is developed based on algebraic equations for uniformly distributed loads to determine the optimal operation, size and location of the DG in order to achieve required levels of network voltage. The developed method is simple to use for conceptual design and analysis of distribution system expansion with a DG and suitable for a quick estimation of DG parameters (such as optimal operating angle, size and location of a DG system) in a radial network. A practical network is used to verify the proposed technique and test results are presented.

Response coordination of distributed generation and tap changers for voltage support

The recent introduction of the competitive electricity market in many countries has sparked a renew trend in connecting small-size generators into distribution networks. Those new generators together with different other types of equipment such as On-load Tap Changing (OLTC) transformer, shunt capacitors, shunt reactors, etc, will all participate into the voltage regulation process in the power systems. Poor coordination between these devices may cause unnecessary operations, and consequently unnecessary wear, unnecessary energy consumption as well as poor voltage quality. In this paper, we present an innovative strategy to coordinate the voltage control actions in a distribution system with more than one voltage regulating device. The method for voltage control coordination is developed based on the priority level of each regulating device and implemented through communication. A sensitivity-based technique for determining the control zones of the regulating devices has been developed. A practical system with tap changers and distributed generator has been chosen to test the developed control method. Simulations have been carried out extensively on a practical distribution system to show the effectiveness of the method.

A novel tuning method for advanced line drop compensator and its application to response coordination of distributed generation with voltage regulating devices

Nowadays, the integration of small-scale electricity generators, known as distributed generation (DG), into distribution networks has become increasingly popular. This tendency, together with the falling price of DG units, has a great potential in giving the DG a better chance to participate in the voltage regulation process, in parallel with other regulating devices already available in the distribution systems. The voltage control issue turns out to be a very challenging problem for distribution engineers since existing control coordination schemes need to be reconsidered to take into account the DG operation. In this paper, a new tuning method for the line drop compensator has been proposed, and it is applied for the control coordination of DG with other regulating devices in the network, which is able to utilize the ability of the DG as a voltage regulator and, at the same time, minimize the interaction of DG with another DG or other active devices such as the on-load tap changing transformer (OLTC). The proposed coordination technique has been developed based on the concepts of protection principles (magnitude grading and time grading) for the response coordination of OLTC, DG unit, and other regulating devices. A distribution feeder with a tap changing transformer and DG unit has been extracted from a practical system to test the proposed control technique. The results show that the proposed method provides an effective solution for coordination between OLTC and DG, DG-DG, or DG and voltage regulating devices, and the integration of protection principles has considerably reduced the control interaction to achieve the desired voltage correction.