2164 results about "Power quality" patented technology

A system, method and computer program product provides for power line communications (PLC) over electric power lines includes a device mountable near an electrical distribution transformer (DT) to provide a high speed interface and communicates with one or multiple access devices, which provide low speed interfaces for analog signals or digital signals over RS 232, RS 485, optical, wireless and Ethernet. The device transmits data to/from these access devices over the electric lines to other repeaters over one or more wires of an electrical line or over multiple lines, and serves to strengthen and improve signal quality. Upon detecting a wire or line is having problems carrying data, the data is sent over other wires, and upon power line failures, wireless backup to mobile/GSM and WiMax networks is utilized. The device permits utilities and others to read electric meters, monitor the power quality of the distribution grid and detect power losses/failures/outages, and permits telecom service providers and others to provide a communications link to cell phone towers, WiFi Access Points and enable broadband Internet and telephony in rural, remote or sparely populated areas.

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

The invention relates to a super capacitor energy storage type power quality compensator. A system structure comprises a compensation transformer, a series compensator, a parallel compensator, a super capacitor group, a current foldback circuit, a bidirectional DC/DC chopper circuit, a signal sampling circuit, a control circuit, a drive circuit, a human-computer interface and corresponding auxiliary circuits, which form a three-phase three-wire system topological structure. By utilizing the excellent characteristics of great power density, high charging and discharging speed and long cycle life of a super capacitor, the super capacitor energy storage type power quality compensator is matched with the DC/DC chopper circuit to form an energy storage control system which plays the roles of adjusting power and stabilizing the voltage of a direct current bus in work. The invention also has the functions of dynamic voltage recovery, active filter and reactive compensation and can ensure that a load can obtain rated sine voltage and the current of a grid is sine current with the same direction (unit power factor) with that of a voltage fundamental wave positive sequence active component, thereby comprehensively improving the quality of power. The invention has positive generalization and application value for both the public grid and users.

A universal smart energy transformer module (USETM) that uses an array of sensors to monitor and measure characteristics of the electrical power delivered and utilized at a location, along with other conditions in the area surrounding the location. The invention then uses the data from these sensors to determine the condition and performance of the transformer (for example, its input and output, power quality etc.) and also to identify any anomalies detected within the local power system that could threaten reliable electric supply on the electric grid, or pose a danger to people. A notification of such condition may be distributed using the secure, uninterruptible communications system.

The invention relates to a control system of a flexible wind power DC convertor on the sea, which pertains to the technical field of power transmission in wind power generation and comprises the doubly closed loop control structure of a sending end rectifier on the sea and the doubly closed loop control structure of a receiving end inverter on the coast; the doubly closed loop control structure of the sending end rectifier on the sea is used for controlling the active power of a flexible DC transmission system and the voltage stability of a wind power AC system; the doubly closed loop control structure of the receiving end inverter on the coast is used for controlling the constant voltage of the DC side of a receiving end convertor and the dynamic regulation of the reactive power of the main network accessing end of the receiving end convertor; two control structures are mutually independent and no data communication exists between the two control structures. The control system can fast and correctly control the active power of wind power transmission on the sea as well as promote the stability of the wind power AC system on the sea and the transmission efficiency and the power quality of the whole DC transmission system.

This invention deals with an advanced Real-time Grid Monitoring System (RTGMS) suitable for both single-phase and three-phase electric power systems. This invention provides an essential signal processing block to be used as a part of complex systems either focused on supervising and diagnosing power systems or devoted to control power processors interacting with the grid. This invention is based on a new algorithm very suitable for real-time characterization of the grid variables under distorted and unbalanced grid conditions. The main characteristic of this invention is the usage of a frequency-locked loop, based on detecting the grid frequency, for synchronizing to the grid variables. It results in a very robust system response in relation to existing technique based on the phase-angle detection since grid frequency is much more stable variable than the grid voltage/current phase-angle, mainly during grid faults. Moreover, the algorithm supporting this invention is very efficient and can be implemented in regular industrial microprocessors. These features make the RTGMS object of this invention ideal to be applied in the control of distributed generation systems (DGS), flexible AC transmission systems (FACTS), power quality conditioners (PQC) and uninterruptible power supplies (UPS). In all these systems, the fast and precise real time detection of the voltage and/or current sequence components under grid fault conditions is a crucial matter.

An intelligent electronic device (IED) integrating a power metering unit (PMU) and a merging unit that combines signals from both analog transformers and digital transformers into a set of merged digital samples. Analog current/voltage signals from analog CTs/PTs are received at the IED's analog inputs and converted to digitized samples. Digital current/voltage samples from digital CTs/PTs are received via point-to-point connections at digital inputs of the IED. A tagging unit applies metadata tags to the digitized and digital samples. The metadata tags include the transformer providing the input signal, sampling rate, primary and/or secondary timestamps, scaling values, calibration values, and/or the location of the IED in the electrical system. The PMU performs metering and/or power quality calculations on the samples, and the calculation results are formatted and transmitted via a master-slave protocol to a requesting master. A grouping unit groups the merged samples into default or custom groupings, which are formatted and transmitted over a network via a publish-subscribe mechanism.

A system and method for monitoring and controlling utility meters is provided. A collar communicatively connected to the utility meter monitors power usage and provides usage data, power quality data, and other data to the utility and the customer. The system provides for pre-pay power, and the collar relay can automatically connect or disconnect power to a customer as required. The system provides intelligent remote control of utility meters via wireless or other communications means.

The present invention relates to a micro-power source for successfully implementing a microgrid and to a control method for realizing smooth reconnection between the microgrid and an upper electric power system and smooth switching between the control modes of the micro-power source. A micro-power source sectionalizes an electric power system into an upper electric power system and a lower electric power system, and enables the lower electric power system to be independently operated in an island mode and to smoothly switch between a grid-connected mode and the island mode. As a result, a hierarchical microgrid is implemented with sectionalized sub-microgrids. One of the merits of the hierarchical microgrid is that each consumer group can be supplied with high quality power regardless of the power quality of the other consumer groups, and various types of services independently.

The invention relates to a smart micro-grid system. The smart micro-grid system comprises a local control layer, a network communication layer, a master station layer and a software layer, wherein the local control layer is in communication with the master station layer through the network communication layer, and the master station layer is in communication with the software layer through an information interaction bus. The smart micro-grid system integrates photovoltaic power generation, wind power generation, multiple types of energy storage systems multiple in capacity and modern power electronic, communication and control technologies. While high-reliability power supply is achieved, optimized allocation of renewable energy resources and high-reliability power supply to loads in a micro-grid are achieved; the interaction relation between the micro-grid and an external power grid is reflected correctly, and the effect of distributed energy on improvement of power supply reliability is fully shown; operation data of photovoltaic, wind power and energy storage systems and the micro-grid systems can be collected and stored, and the operation data are accumulated for researches on key technologies about micro-grids. The smart micro-grid system solves the problems that an existing micro-grid system is low in energy utilization ratio and poor in environmental benefit, electric energy quality and power supply reliability.

The invention discloses a wave energy and solar energy driven unmanned monitoring ship for a marine environment, which comprises a ship body and an unmanned control system, wherein the ship body has a shape of rigid inflatable boat; the unmanned control system comprises a ground remote control system and a ship-loaded system which are coupled with each other through a wireless data link; the ground remote control system comprises a remote control computer, a wireless network bridge and corresponding top-layer application software; the ground remote control system is used for receiving, analyzing and displaying a ground remote control command and data; a serial port of the remote control computer is connected to the wireless network bridge; and the ship-loaded system comprises a navigationcontrol subsystem, a communication subsystem, a navigation information sensing and collecting subsystem, a wave energy and solar energy power generating and supplying subsystem and a data collecting subsystem. No diesel motor is required in the wave energy and solar energy driven unmanned monitoring ship, a wave energy generating system and a solar energy generating device of the ship are directly used for supplying power, the quality of output electric energy is stable and the electromagnetic compatibility is excellent, thereby ensuring the normal work of ship-loaded equipment under a complex marine environment.

The invention discloses an early warning method of stable-state index of power quality. The method is realized by support from a power quality online monitoring device and a computer. The method is characterized by comprising the following steps of: (1) selecting power quality indexes in advance, including voltage deviation, voltage total harmonic wave, short time flicking, etc, and setting earlywarning threshold values at four grades; (2) acquiring power quality data in real time, and analyzing each power quality index to carry out early warning grading; and (3) saving the values calculatedand a final early warning grade into a database. The early warning method of stable-state index of power quality establishes an early warning structure with two types, including index standard-exceeding type and index abnormal type, and four grades, and adopts time sequence mining algorithm based on high-order statistics in abnormal mining link to analyze potential abnormity of power quality datawith skewness and peakedness. Practice proves that the early warning method is clear in hierarchy, high in algorithm efficiency, strong in accuracy and good in operability. The early warning method is high-efficient and comprehensive.

The invention discloses an electrical energy quality monitoring and evaluating system, which comprises a plurality of electrical energy monitors, a communication network, a plurality of enterprise service platforms and a government service platform, wherein the enterprise electrical energy monitors are connected to the enterprise service platforms through the communication network, and the independent electrical energy monitors and the enterprise service platforms are connected with the government service platform through the communication network; the enterprise service platforms are used for receiving basic electric power parameters acquired by the enterprise electrical energy monitors at monitoring points inside the enterprises, displaying the change conditions of the electric power parameters of enterprise distribution networks, and transmitting data to the government service platform at certain time intervals; and the government service platform is used for receiving the electric power parameters of the enterprise distribution networks transmitted by the enterprise service platforms and the parameters transmitted by the independent electrical energy monitors at the monitoring points in the regional distribution networks, and performing energy consumption audit, transient and stable electrical energy quality analysis, electrical energy quality level evaluation, harm extent evaluation and evaluation of providing the corresponding electrical energy quality improvement scheme and electrical energy quality improvement effect.

The invention discloses a cooperative control method for participating in the frequency modulation and pressure regulation of a power system by a wind storage cluster. The method comprises the following steps: using the over-speed control and pitch angle control of a wind turbine generator to preserve a part of active power and reactive power for the wind storage cluster as the frequency modulation and pressure regulation standby power of the power system in accordance with the active power and reactive power capacity standby requirements given by the operation condition of a wind power plant, wind speed and the scheduling of the power system; determining the size of the active power and reactive power given by the wind storage cluster in accordance with the state of the wind storage cluster when the frequency or voltage of the power system is fluctuated; and finally, by reference to the capacity limitation of a wind turbine generator and stored energy, determining the final output condition of the wind turbine generator and the stored energy. According to the cooperative control method provided by the invention, the condition that the wind storage cluster participates in the system frequency and voltage regulation, and the stability and electric energy quality of the power system can be effectively improved by less energy storage capacity allocation in the power system with higher wind power permeability.

The invention relates to a virtual synchronous generator control method based on self-adapting moment inertia. The output of a grid-connected inverter in distributed generation is connected with an AC bus of a filter capacitor Cf which is in parallel connection with the grid-connected inverter through a filter inductor Lf; sampling is performed to obtain the output power, the voltage and the current of an output interface of an inverter; the output power, the voltage and the current are transmitted to a VSG (virtual synchronous generator) algorithm; the calculated terminal voltage of a VSG stator is sent to be controlled by a voltage external loop; the voltage external loop adopts a PI controller to stably load the voltage; the current of the filter capacitor is sent to be controlled by a voltage internal loop; the voltage internal loop adopts a PI controller to increase the response speed; a control signal is outputted by a voltage-current dual-closed loop to the grid-connected inverter; the moment inertia in the virtual synchronous generator in the control method can be changed in a self-adapted manner according to the change capacity of the system frequency. Through the adoption of the virtual synchronous generator control method disclosed by the invention, the transient state process of the system is reduced; a great deal of harmonic waves in the system is offset; the stability of frequency and the stability of voltage can be improved; the adaptability and the power supply quality of a micro-electrical network are improved; the problem that in a conventional method, the output frequency is reduced, is solved.

The invention relates to a megawatt wind generating set combination control policy. When the wind speed of a wind generator fluctuates at rated wind speed, a torque control policy and feather control policy simultaneously remain in operation state, so as to realize undisturbed switching between a feather PID controller and a torque PID controller. The invention makes the best of the integral saturation characteristic of PID algorithm, so that switching between the torque PID controller and the feather PID controller is smooth and sensitive, mutual interference between the feather controller and the torque controller in the previous switch mode switching process while only one controller is ensured to operate at the same time, drastic fluctuation of wind generator power when the wind speedfluctuates at the rated wind speed is avoided, further load impact is reduced, electric energy quality is improved, reliability of the wind generating set is improved, and operation performance of the wind generating set is improved.

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

The integration method includes steps: using private comm protocol of each manufacturer to obtain private data collected by quality monitoring device for isomeric quality of power supply (QPS); keeping to IEC 61850 modeling rules to convert private data to object model of QPS data accorded with IEC 61850 standard; based on mapping principle to map IEC 61850 model to united OPC data format; following OPC criterion to provide OPC open application program interface. The invention also discloses data gateway of QPS in multiple protocols based on IEC 61850 and OPC. Using the method and gateway, the invention integrates and connects each isomeric QPS monitoring devices to realize sharing and unifying system resources as well as transparent inter accessing information between the monitoring device and automatic system of digitalized transformer substation. Advantages are: abundant comm protocols and intefaces, raised integrative efficiency, and satisfying requirement in future.

The invention discloses a microgrid energy management system capable of realizing load management. The energy management system comprises a man-machine interaction module, a prediction module, a system analysis module, a dispatching and control module, and a system management module. The system performs collection and monitoring on information of the output power of a distributed power generation unit (including a wind turbine generator, a photovoltaic array and a diesel engine set), the charging-discharging states of a storage battery, the load power, the electric energy quality information of unit nodes, and the like, then carries out data analysis and processing under the condition of satisfying electrical characteristic constraint conditions of operating conditions and physical equipment, formulates a corresponding optimal control strategy according to the current microgrid operating condition and external application requests, coordinates and manages the operations of the distributed power supply, the load and other modules in the microgrid system, optimizes the energy flow and utilization of the microgrid system, outputs by using renewable resources, supplies electric energy capable of satisfying the required quality to user load at the lowest operating cost, and realizes the system optimization and dispatching.

A brushless generator with permanent-magnet multi-pole rotor disks and stator winding disks in their axial magnetic field includes integral electronics to efficiently generate regulated DC current and voltage from mechanical input power over a broad speed range. All power for the electronics is provided by rectifier diodes from its stator windings. Differential amplifiers provide stator voltage feedback signals. Its power rating is scalable, depending on the number of its disks. Having no iron cores and no gears, it incurs no cogging torque, and no gear friction. Integral power control electronics includes high-frequency pulse-width-modulated boost regulation, which provides regulated current at requisite voltage over its broad speed range. A main wind-powered embodiment to produce DC power for a constant voltage DC load over a broad speed range includes signal processing so output power varies according to the third power of speed. Combined boost-regulation, zero cogging torque, and no gearing, enable a wide speed range, for better power quality and higher wind energy yields.

The invention discloses a comprehensive collection method and a device with three-state data of electrical parameters: steady state, fault recorder data and dynamic data, and the device is characterized in that the device consists of a high-precision time synchronization module, a synchronous sampling pulse module, an alternating current signal conditioning module, an A/D sampling module, a direct current signal conditioning module, a voltage frequency conversion module, a switch quantity signal conditioning module, a signal processing module, a recording module and a high-speed network communication module, etc. The method and the device have the advantages that: the use of the high-precision time synchronization module and the high-performance signal processing and the communication technologies can realize the synchronous collection of the three-state data of the electrical parameters, complete the functions of monitoring, fault recording, phase angle measurement and power quality analysis, etc., improve the data processing capability and the sampling precision, improve the real-time property of an automatic system of a substation, simplify the design, the manufacture and the operation of secondary equipment of the automatic system of the substation and greatly reduce the construction cost and the maintenance cost of the substation.

The invention discloses a design scheme of an energy storage bidirectional current converter for a high-capacity storage battery. The current converter utilizes a modularization design idea and supports the idea that a plurality of branch DC/DC modules are connected in parallel and then are connected to a DC bus bar. The problems of circulation and current sharing caused by serial and parallel connection of battery packs are solved. Energy collected by the DC bus bar is exchanged with the energy of a power grid or an independent load through a backward DC/AC current converter. Due to the adoption of a technology of time-sharing rotation and dynamic hibernation, the efficiency of a system under the low power and electric energy quality at the AC and DC sides can be effectively improved so as to realize balanced use of the battery packs. Each storage battery branch is subjected to automatic and intelligent charge and discharge management, a control function and a protection function are completely independently configurated, and the highest availability of the system is ensured. An experimental result shows that the energy storage bidirectional current converter for the high-capacity storage battery has good universality, practicality and application prospect.

The invention relates to a 3D-coordinated power grid energy management system and a power grid evaluation and control method, which belongs to the field of scheduling automation of power system. The system comprises a power grid model reconstruction sub-system, a power grid safety evaluation and alarm sub-system, an active frequency optimization control sub-system and a passive voltage optimization control sub-system, and a background calculation sub-system and a system foreground. The method comprises following steps: tracking isoline of an external power grid and automatically reconstructing a global power grid model; automatically executing online safety analysis integrated with static power grid, dynamic power grid, voltage stabilization, coordination of relay protection setting values, etc., and online recognizing the safety state of the power grid; alarming for normal unsafe condition, and carrying out prevention control; alarming for emergent conditions, and carrying out correction control calculation; and carrying out realtime active scheduling closed-loop control and passive voltage optimized closed-loop control under normal safety condition. The invention can achieve comprehensive and coordinated closed-loop control for the safety of the power grid, the economy and the electric energy quality.

A Three-phase Power Signal Processor (TPSP) is disclosed for general three-phase power system applications. The TPSP is developed based on the concepts from adaptive filter and dynamical systems theories. The structure of the TPSP is unified as it provides a multiplicity of the signals and pieces of information without the need to change, modify, or enhance the structure or to impose excessive computational time or resource requirements. The presented TPSP receives a set of three-phase measured signals, which can be voltage, current, magnetic flux, etc, and provides (1) the instantaneous and steady-state symmetrical components, (2) the fundamental components, (3) the peak values (magnitudes) of the symmetrical components, (4) the frequency and its rate of change, (5) the synchronization signal(s) and zero-crossing instants, (6) the phase-angles of the symmetrical components, and (7) the disturbance signatures. Two or more TPSP units, when properly augmented, further provide (8) the individual harmonic components, (9) the inter-harmonics, (10) the instantaneous real and reactive current components, (11) the total harmonic distortion, dc-offset, and power factor. The TPSP can serve as the building block for various signal processing requirements encountered in the context of power system applications including power systems control, protection, monitoring, and power quality.

The invention relates to a power quality comprehensive evaluation system in the technical field of the electric power application; in the invention, a power quality collecting module obtains all items of power quality indexes from an electric fence; a power quality index grading module divides the power quality indexes obtained from the power quality collecting module into setting grades according to national standard or international generally recognized requirements; a probability distribution matrix obtaining module obtains probability of the power quality in each grade, and then the probability of the power quality index in each grade is obtained for obtaining a probability distribution matrix; a weight vector obtaining module obtains weight vector of the power quality index; an evaluation quantized value obtaining module obtains the only quantized value of the power quality comprehensive evaluation according to the probability distribution matrix and the weight vectors of all the indexes; a power quality evaluation module compares the only quantized value with the evaluation system for obtaining power quality evaluation result. The system can really reflect the probability characteristics of the power quality indexes and can comprehensively and objectively carry out comprehensive evaluation to the power quality.

The invention discloses an on-line monitoring and state evaluation system for photovoltaic grid-connected power generation. The system comprises an electric quantity collection unit, an input unit, an output unit, an ARM9 data management unit, a CPLD/FPGA interface conversion unit, a temperature and illumination measuring unit and a power supply unit. According to the invention, a multi-CPU whole embedded system that is composed of an ARM 9, an ARM7, a DSP is employed, so that reliability of a measurement control unit is substantially improved and expandability is high; an FFT is used as a basic electrical energy quality measuring algorithm, high precision sampling and synchronous transmission are utilized and real-time measurement on an environmental parameter is combined; and moreover, an inter-harmonics measuring algorithm and a harmonics source positioning and responsibility distribution method are put forward; consequently, on-line and real-time monitor on an electrical energy quality and an operation state of a photovoltaic grid-connected power station comprehensively and various stable state and transient events are recorded. Therefore, it is convenient for operation staff to visually monitor the operation state of the photovoltaic grid-connected power station as well as reliable data and sufficient basis are provided for analyzing causes of a disturbance and a fault, wherein the disturbance and the fault occur in the operation; and thus the invention of on-line monitoring and state evaluation system is an important basis for realization of new energy access of a power grid.

The invention discloses an island detection method of a high-power photovoltaic grid-connected converter. The method comprises the following steps of: determining whether a system operates at a grid-connected power generation state, and starting up an island detection algorithm instantly if the system is at the grid-connected power generation state; detecting whether the frequency of the voltage of a port power grid is within the normal range in real time, if the frequency is not within the normal range, considering that the system is at the island state, and carrying out automatic safety stop on the system; adding reactive current Iqdisturb with the duration of td periodically within the normal range; and superposing the reactive current Iqdisturb and reactive control Icqset of the converter, thus an axis q component reference Icqref of grid-connected current of the converter is formed finally. The contradiction between two aspects of reliability of detection and the quality after grid-connected electric energy reduction for the traditional island detection algorithm is effectively solved by the method provided by the invention, and the implementation method is simple and effective.

An electronic electric meter for use in a networked automatic meter reading environment. The electric meter retrofits into existing meter sockets and is available for new meter installations for both single phase and three phase electric power connections. The electric meter utilizes a modular design which allows the interface modules to be changed depending upon the desired communication network interface. The meter measures electricity usage and monitors power quality parameters for transmission to the utility. The gateway node transmits this data to the utility over a commercially available fixed wide area network (WAN). The meter also provides direct communication to the utility over a commercially available network interface that plugs into the meter's backplane or bus system bypassing the local area network communication link and gateway node.

The invention provides a smart grid-oriented power quality monitoring system and a smart grid-oriented power quality monitoring method, which relate to the field of monitoring of power quality. The system comprises a distributed online/offline node detection module, a network communication module, a distributed database module and a comprehensive management module of the power quality monitoring system, wherein the distributed online/offline node detection module comprises a parallel analog-to-digital conversion module and a signal processing module so as to realize distributed detection of asmart grid. In the technical scheme provided by the invention, a plurality of analog-to-digital conversion chips are connected in parallel and an analog signal is sampled, so that high-accuracy sampling rate of signals is increased and the detection requirement on transient power quality signals is met; based on a programmable logic chip, online analysis and data compression are realized by a parallel signal processing algorithm; a distributed database is adopted, so that system reliability is enhanced and system upgrade is promoted; and a global positioning system (GPS) and a communication network module are adopted, so that a distributed network system is realized, and power quality monitoring of the smart gird is supported powerfully.

The invention discloses a power adjustment method for a hybrid energy storage photovoltaic power station. In the operating process of the photovoltaic power station, voltage of a direct current bus of the photovoltaic power station and voltages of a super capacitor group and a lithium battery group which are connected with the direct current bus respectively through two bidirectional direct current/direct current (DC/DC) controllers are detected in real time, active power output of a photovoltaic power supply is detected in real time, and meanwhile power output values of the super capacitor group and the lithium battery group for fulfilling an electric energy quality adjustment and control aim of the photovoltaic power station or finishing a scheduling task are quickly calculated; and running states of the two bidirectional DC/DC controllers are controlled according to a calculation result, and thus a charging process and a discharging process of the super capacitor group and the lithium battery group can be controlled. By the method, the advantage of high energy density of a lithium battery and the advantages of long circulation service life and high power density of a super capacitor are given a full play, the problems of low electric energy quality and difficulty in participation in power grid scheduling which are caused by grid-connected running of the photovoltaic power station can be solved; and popularization and application of the photovoltaic power station are facilitated.