Power-flow study

About: Power-flow study is a research topic. Over the lifetime, 8091 publications have been published within this topic receiving 155053 citations. The topic is also known as: load-flow study.

Nonlinear Programming Solutions for Load-Flow, Minimum-Loss, and Economic Dispatching Problems

Abstract: A unified approach to load-flow, minimum-loss, and economic dispatching problems is presented. A load-flow solution is shown to coincide with the minimum of a function of the power system equations. An unconstrained minimization method, developed by Fletcher-Powell, is used to solve the load-flow problem. The method always finds a solution or indicates the nonexistence of a solution. Its performance is highly independent of the reference- slack bus position and requires no acceleration factors. Several constrained minimization techniques that solve the minimum-loss and economic dispatching problems are investigated. These include the Fiacco-McCormick, Lootsma, and Zangwill methods. The technique finally recommended is shown to be an extension of the method used to solve the load-flow problem. The approved IEEE test systems, and other systems whose response to conventional methods was known, have been solved.

Application of Newton's optimal power flow in voltage/reactive power control

Abstract: The authors consider an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints for the treatment of power system security and economy is also proposed. For the real-time voltage/receiver power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and a corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states. >

Providing premium power through distributed resources

Abstract: The modern industrial facility depends on sensitive electronic equipment that can be shut down suddenly by severe power system disturbances. A large number of these disturbances on the power system are a result of line faults which can cause momentary voltage sags. This results in equipment malfunctioning and high restart cost. This papers describes the control of distributed resources as a solution to such problems. In particular the focus is on systems of distributed resources that can switch from grid connection to island operation without causing problems for critical loads.

Hybrid Active Filter for Reactive and Harmonics Compensation in a Distribution Network

Abstract: The problem of reactive power and harmonics in the medium voltage level of a power distribution system is considered in this paper. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The alternative of a shunt hybrid active filter connected to the 13.8-kV level to enhance the power quality is analyzed in this paper. This proposal uses the existing capacitor bank to build a hybrid filter in which the complementary compensation is performed by the active filter. The performance of the hybrid filter is evaluated with extensive simulations considering reactive power, harmonics, and unbalance compensation. It shows very good behavior in steady-state and transient conditions.

Method and apparatus for tracking maximum power point for inverters, for example, in photovoltaic applications

Abstract: A power system employs an outer voltage feedback loop and an inner current feedback loop to control a power converter, such as a DC to AC inverter for transferring electrical power between a power source, for example a photovoltaic array, and a load, for example a power grid. The outer loop accommodates variations in the output of the power source, for example accommodating anomalies in IV characteristics such as IV droop characteristic associated with photovoltaic cells. The outer loop may employ a first control regime or a second control regime, for example, dependent on whether a DC bus voltage or power is smaller than a value corresponding to measurement resolution or expected noise.