Most of the loads are inductive, and must be supplied with lagging reactive power. Thus careful coordination of these controls is necessary to ensure the desired accuracy, robustness and speed of response is obtained without undesirable interactions. Reactive support and control involves numerous functional entities. Power factor and reactive power university of wisconsin. Coordinated control method of voltage and reactive power. However, bulk reactive power cannot be transmitted as far as real power see appendix 4, examples 1, 2, and 3. Real power accomplishes useful work while reactive power supports the voltage that must be controlled for system reliability. Reactive power is a measure of this unproductive power. Active and reactive power coordination control strategy of.
This paper proposes a twolevel reactive power coordination and voltage restoration strategy for microgird using model predictive control mpc approach. Reactive power cannot be transmitted over a long distance or through power transformers due to excessive reactive power losses. It is economical to supply this reactive power closer to the load in the distribution system. Also it regulates the steady state and temporary overvoltages and therefore the disastrous blackouts can be avoided. In this control strategy, the voltage of pcc is tracked by pv system in real time. Coordination of reactive power scheduling in a multiarea. The need for reactive power coordination controller for upfc arises from the fact that excessive bus voltage the bus to which the shunt converter is connected. Pdf active and reactive power coordination control strategy of. If suitably designed, it is capable of improving voltage quality significantly, meaning that losses in equipment and power systems are reduced, the. Reduce your reactive power improves efficiency and saves costs. Apparent power is measured in the unit of voltamps va and is symbolized by the capital letter s. Simulation of real and reactive power coordination using. Concepts of reactive power control and voltage stability methods in power system network.
Pdf concepts of reactive power control and voltage. If reactive power is in excess in power system than voltage may go up and in case of shortage of reactive power voltage may be low. The rpc tool will optimize reactive power controls shunt. Request for proposal for reactive power coordination tool. Importance of reactive power in power generation and. Reactive power does not do any work, so it is represented as the imaginary axis of the vector diagram. This paper main objective is to reduce switching operations of reactive power devices ultc and shunt capacitors together with system power loss. Reactive power coordination tool ercot is actively working on a project to develop a multi hour look ahead tool to improve reactive power coordination within the ercot region. Stability and reliability of electrical power system depends on reactive power management. In this article, we will explain various aspects of reactive power, what its role is in power system and how it can be injected.
Reactive power is when the current flow, caused by ac voltage applied across a device, results in the current flow being either ahead or behind the applied ac voltage. Reactive power is the resultant power in watts of an ac circuit when the current waveform is out of phase with the waveform of the voltage, usually by 90 degrees if the load is purely reactive, and is the result of either capacitive or inductive loads. The voltage and reactive power controls that are active in the transient time frame are the controls of the. Coordination of controls of renewable power plants to meet. Reactive power compensation in power systems can be either shunt or. Reactive power is critical to maintaining voltage levels on the transmission system. However, we find the concept of reactive power little bit confusing because reactive power does not contribute in doing useful work. Download reactive power compensation a practical guide pdf.
Reactive power has limited effect on lv distribution networks and can often be ignored for initial assessment of the connection of small domestic pv systems. Reactive power has a profound effect on the security of power systems because it affects voltages throughout the system. Overview of electric reliability council of texas, inc. Coordination of reactive power scheduling in a multiarea power system operated by independent utilities yannick phulpin department of power and energy systems, supelec school of computer and electrical engineering, georgia institute of technology october, 2009 phd defense. Voltage is supported through the supply of reactive power. By reactive power compensation we can control the power factor and reduce the. Reactive power can arise in the external network and in the local network, and may be caused.
Reactive power management brings into focus this subject which has assumed importance due to high transmission and distribution losses. Conclusion from all the previous discussion we can conclude reactive power compensation is a must for improving the performance of the ac system. Reactive power is an imaginary power, but still, it is needed in the power system. Importance of reactive power for system electrical notes. Therefore, the functional entities which need to plan, operate, and control reactive power are more localized and close coordination is. As a result, the generator will operate asynchronously as an induction machine, typically with 2% to 5% slip, and draws the reactive power from the system for the excitation instead of generating reactive power to the system 4. This paper proposes a new real and reactive power coordination controller for a unified power flow controller upfc. Find important discussion regarding importance about reactive power and how it is useful to. Nerc reactive power planning guideline december 2016.
Reactive power coordination strategies with distributed generators in distribution networks. Wind farm reactive power coordination centralized wind farm control voltage regulation at pcc q dispatch based on reactive power capability for each wtg sendreceive information using iec 61850 goose q set points for each wtg q capability from each. Reactive power supply should be located in close proximity to its consumption. The relation between active, reactive and apparent power can be expressed by representing quantities as vectors, which is also called as power triangle method as shown below. This application will be used for both realtime operations and offline planning. Pdf aiming at the voltage rise due to the photovoltaic generation system pvgs at the point of common coupling pcc, the cause is. Apparent power is often expressed in voltamperes va since it is the product of rms voltage and rms current. How reactive power is helpful to maintain a system healthy. Active, reactive and apparent power electronics hub. Reactive power control in electrical power transmission system. Reactive power is supplied locally, mainly because of its dependence on voltage difference, and it is usually necessary to site reactive devices near or at the location. Coordination of reactive power scheduling in a multiarea power. It creates an extra load on the installation, equipment and transport infrastructure such as cables and pipes. Ac power the behavior of ac machines and systems are often easier to understand by working with power, rather than working with voltages and currents active, reactive, and apparent power apply to steadystate ac circuits with sinusoidal waveforms only.
Reactive power coordination strategies with distributed. The effect of pv generation supplying local loads reduces the flow of. Only when current is in phase with voltage is there actual work done, such as in resistive. Distribution system load and solar system power will predict one day in advance and grey wolf optimizer gwo algorithm proposed to.
In ac circuits, active power is the real power consumed by the equipment to do useful work meaning the power dissipated by a load, whereas reactive power is an imaginary power which is not used directly for work. It is the actual outcomes of the electrical system which runs the electric circuits or load. Difference between active and reactive power difference. The provision of voltage support from distribution systems to transmission networks requires new costeffective coordination schemes to drive thousands of noncentrally monitored distributed energy resources ders. Real and reactive power coordination for a unified power flow.
Using an analogy to a municipal water system, think of voltage as equivalent to water system pressure without it water just sits in the pipes and, with too much, pipes explode. This impedes the electrical current, causing reactive power to be required. Investigation on generator loss of excitation protection. Here, the principle and strategies of voltage regulation based on active and reactive power in pvgs are proposed. Pdf reactive power coordination strategies with distributed. Reactive power loads must be supplied either locally from customerowned devices or from the system itself. This paper provides practical guidance for providing this coordination in the following specific protection areas. Optimal coordination control strategies are provided for decision makers by means of solution of the multitarget multisite reactive power coordination control system with consideration of reactive power device loss, and energy conservation and consumption reduction are realized while system voltage is. However, the flow of reactive power is the main factor determining the voltage on high voltage. The combination of reactive power and true power is called apparent power, and it is the product of a circuits voltage and current, without reference to phase angle. Reactive power compensation techniques in transmission. Most loads consume reactive power, highly nonlinear and generate harmonics. Simulation of real and reactive power coordination using csc based ipfc for power quality issues. Pdf active and reactive power coordination control.
Due to reactive power compensation techniques the working of hvdc conversion terminal becomes better 4. Importance of reactive power is increasing with growing demand for electrical power by many domestic and industrial utilities, in power system network. Reactive power compensation techniques in transmission lines. Reactive power or anything else involving the word reactive in electricityelectronics is, by definition, the power consumed actually. Analysis of reactive power in power system electrical. Aiming at the voltage rise due to the photovoltaic generation system pvgs at the point of common coupling pcc, the cause is analysed with power transmission theory. Power factor is a measure of the relation between real and reactive power. This tool is being called the reactive power coordination rpc tool. Voltage control is a fundamental requirement to ensure secure operation of microgrid, especially for islanded microgrid. It is almost universal for some of the reactive load to be compensated locally as powerfactor correction.
Today, reactive power is present in many installations. Page 7 11nov16 control time frames transient timeframe 0 to 5 seconds the voltage and reactive power controls that are active in the transient time frame are the controls. Coordination of distributed reactive power sources for. Changing reactive power behaviors of distribution systems e. Twolevel predictionbased reactive power coordination and. The twin problems, reactive power compensation and harmonics reduction are carried out using shunt passive filters. It is required to generate energy in a more efficient, reliable and cost effective way. Sufficient static and dynamic voltage support is needed to maintain voltage levels within an acceptable range. The comprehensive resource on reactive power compensation, presenting the design, application and operation of reactive power equipment and installations the area of reactive power compensation is gaining increasing importance worldwide. What is active, reactive and apparent power definition. It is connected in series with the transmission lines through three single transformers. Simulation of real and reactive power coordination. Reactance can be either inductive or capacitive, which contribute to reactive power in the circuit. Wind farm reactive power coordination scheme using iec.