Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
  • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/34—Arrangements for transfer of electric power between networks of substantially different frequency
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
  • H02J3/381—Dispersed generators
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
  • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
  • H02J3/48—Controlling the sharing of the in-phase component
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
  • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
  • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
  • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
  • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
  • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
  • H02J2300/20—The dispersed energy generation being of renewable origin
  • H02J2300/28—The renewable source being wind energy
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
  • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
  • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
  • H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
  • H02M1/00—Details of apparatus for conversion
  • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
  • H02M1/007—Plural converter units in cascade
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/70—Wind energy
  • Y02E10/76—Power conversion electric or electronic aspects
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
  • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Definitions

• the present invention relates to a system that, associated with any power source that can be coupled to the general distribution network, allows the power in said network to be adjusted to the consumption parameters, both in terms of the incidence in said network of the power source itself in which it is installed, as with respect to the incidence of other minds connected to the same network and lacking such a system.
• Wind farms lack planning for the injection of power into the distribution grid, since they depend on wind conditions at different locations. This type of operation produces effects of instability of the frequency and voltage of the distribution network, which have to be palliated by the rest of the conventional generating plants, which is a very important problem in the distribution companies of the electricity sector. Therefore, the inclusion in a variable speed wind turbine of features that provide control in the injection of power in the distribution grid contributing to its dynamic stability and frequency control is of extraordinary interest for the distribution company in accordance installed wind power increases.
• variable speed wind turbines is the main field of application of this invention. It is currently the unconventional energy source that allows to contribute to the power grid with sufficient power level to be able to dynamically stabilize it and regulate its frequency.
• the grid connection power converter in variable speed wind turbines, which are controlled in the stator of the electric machine, is essentially an electronic topology similar to that of the converter object of this invention, where there is a continuous voltage busbar DC to the input connected to a DC voltage converter - AC voltage bidirectional AC that allows connection to the distribution grid. Therefore, the electronic interface between the wind turbine and the distribution network allows the integration of the control features claimed in this patent.
• the system proposed in the invention may incorporate a battery-based electrical storage system, coupled directly to the DC direct voltage busbar, or through a DC-DC DC converter, which provides or absorbs the power required to contribute to dynamic stability and regulation of the frequency in the distribution grid.
• the electrical system constituted by the generation, the electricity grid and the consumers, is a system in dynamic equilibrium that collapses if an equality between demand and consumption of electrical energy is not maintained at all times.
• the index that indicates that this is happening is the frequency of the network (50 or 60 cycles / s). Up or down mismatches indicate that more or less is being generated than what is being consumed.
• the generator system has the mechanical inertia of the set of generators that are also electromagnetically coupled to each other (dynamic stability).
• each generator has its own frequency regulator whose signal acts on the power additively to the setpoint set by the operator. In this way, a system is achieved that consumers access in a discretionary manner and that is required total availability and also wave quality.
• the primary energy sources with which the electricity is produced are susceptible to storage either in the form of binders or embalmed water since the electric generators are synchronous, and can be coupled to form a set of great inertia.
• the first would be that of the kinetic energy stored in the mass of the turbogroups, whose energy content is very small in relation to those described later, but which is indispensable for the maintenance of dynamic stability, because continuously and without Delay contributes to the stability of the frequency, by giving the whole inertia.
• Said energy is supplied as power in more or less than the one set by the operator in a proportional way and opposite sign to the frequency errors.
• the turbine regulators carry out this primary regulation mission.
• Said frequency stabilizing effect is not as immediate as the one described above, since it requires the action of valves and mechanisms that introduce delays. The sensitivity of the response will depend on the weighting between frequency regulation versus power regulation set by the operator.
• the third would correspond to the storage of energy at the foot of the plant, or in the reservoir in the case of hydraulics measured with units of days; and with which there is sufficient energy to attend to the programming carried out by the "firching" for the block adjustment of the daily load curve.
• the fourth refers to the strategic medium and long term that would be expressed in years or five years being reflected in the Energy Plans.
• the so-called renewable energies, solar and wind are primary energies for the production of electricity, which are not storable and also do not use synchronous generators directly coupled to the network for technical reasons of mechanical stresses and difficulty of coupling.
• the system that the invention proposes constitutes a remarkable technological advance in this line, so that with it it is not only possible to control the power that a renewable energy source supplies to the distribution network, but also it is also possible to influence direct in the parameters of said network, to correct deviations produced by other energy minds associated with it, contributing to the dynamic stability of the network and the regulation of its frequency (primary regulation).
• the proposed invention provides the power generation system with the possibility of contributing to the improvement of dynamic stability and the regulation of the frequency of the distribution grid, thanks to the control of the active power injected instantaneously, both power active as reactive. In this way, the entire system, or a set of them acting simultaneously, will be able to behave as a conventional power generation plant.
• the system includes, at a minimum, an electrical power generation system, an electronic power circuit for converting said electric energy with variable frequency into electric energy with fixed frequency and an electrical energy storage system connected to a continuous voltage busbar so that said storage system is capable of storing or supplying active or instantaneous power to contribute to the improvement of dynamic stability and frequency regulation of the distribution network.
• the electric power generation system can be implemented in a variable speed wind turbine, in a field of photovoltaic solar panels or in a fuel cell, or even not incorporate an external power source, acting exclusively as a means of controlling the net.
• Figure 1 shows the scheme of the system and the control diagram object of this invention that refers to the integration of an electronic power system based on a bidirectional converter connected to the power grid, which acts as a current source, together with a electrical energy storage system that, feeding on any energy source, in particular wind power, or making use of energy previously stored in the system, coming from the same distribution network, injects or absorbs it from said network in the form of active power contributing to the improvement of its dynamic stability and the control of its frequency.
• Figure 2 shows a general block diagram of the system proposed in this invention that includes an energy storage system and converter for connection to the distribution network with the ability to control the active and reactive power injected into said network.
• a power source can be connected to the input of the system, and it is necessary to incorporate a series of power converters for adaptation to the DC voltage busbar of the main converter.
• Figure 3 shows the general block diagram of the proposed invention used in the description of the preferred embodiment of this documentation, where the invention has been applied to the field of variable speed wind turbines, to contribute to the improvement of stability. dynamic and frequency regulation of the distribution network.
• Figure 3 is a particularization of Figure 2 in case the source of energy connected to the system object of this invention is wind energy.
• the equivalent model per phase of the invention is shown in Figure 4.
• This system injects a current into the network that is controlled instantaneously and can follow an arbitrary waveform, which is imposed as a slogan at the input.
• the invention behaves from the point of view of the network and, considering an equivalent model per phase, as a current source.
• the smoothing coil and the network considered to have infinite power have also been represented.
• Figure 5 shows the block diagram of the preferred embodiment of the frequency control system and the improvement of the dynamic stability of the network based on a closed loop control scheme that regulates the frequency using injection or absorption of active power of the network.
• the invention is constituted by the DC direct voltage converter - AC alternating voltage (1) that connects a power source (14) to the distribution grid (13) and a continuous voltage busbar DC, formed by a set of capacitors (12), to which an electrical energy storage / generation system such as batteries and / or superconducting coil (11) is connected.
• a power control system (3) measures the currents, by means of the corresponding Hall effect measurement sensors (4) and the voltages, by means of the measurement transformers (5), of the power grid in order to generate the firing of the power switches and achieve that the instantaneous active power supplied is the reference power whose setpoint is obtained in the block (7).
• This reference is obtained by adding the power setpoints of the modules (6) (8) and (10) and the reference active power setpoint to be injected from the main power source (15), for example the power injected by a turbine wind.
• the voltage control module (6) measures the continuous busbar voltage, using the voltage sensor (2), and generates the setpoint to contribute to the net power in the module (7).
• the frequency regulation module (10) uses the instantaneous network frequency information, calculated in the module (9) to generate the instantaneous active power setpoint which added to the module (7) contributes to the frequency regulation of the network.
• the equivalent inertial power calculation module (8) uses the instantaneous network frequency information, determined in the module (9), and generates the instantaneous active power ⁇ P ⁇ > which is subtracted from the module ( 7) contributes to the dynamic stability of the network.
• the instantaneous active reference setpoint to be injected or absorbed from the Pref distribution power network is obtained.
• the voltage generated by the power source may be alternating AC or DC continuous, so that in the case of alternating generation a rectifier circuit would be used , which can be controlled or uncontrolled in order to generate a DC continuous voltage. This is due to the fact that the proposed invention uses a DC voltage converter - alternating voltage as a connection to the distribution grid.
• AC that from a DC voltage busbar injects or absorbs current from the network, so that the converter object of this invention and its control behaves like a current source.
• This source injects sinusoidal current in phase with the mains voltage, or with a certain lag, being able to instantly control the active and reactive power injected or absorbed from said network.
• phase-equivalent model of the power system object of this invention acting as a current source is represented in Figure 4.
• the dynamics of the system will be governed by a coil located between the power system and the network to reduce current curling. due to the switching of the power switches.
• the invention is essentially characterized by the fact that it is provided with an electrical energy storage system, which can be implemented by a set of batteries, fuel cell, photovoltaic or solar panel field, or simply by the assembly of capacitors located in the DC direct voltage busbar.
• an electrical energy storage system which can be implemented by a set of batteries, fuel cell, photovoltaic or solar panel field, or simply by the assembly of capacitors located in the DC direct voltage busbar.
• This electrical storage allows that, in the absence of energy from the power generation system, the power converter and its control object of this invention can continue to behave as a source of current by injecting or absorbing instantaneous active power from the network.
• the system of Storage will be complemented by simply using the set of capacitors of the DC busbar, or if the energy need for supply / storage is greater, the use of batteries will be necessary.
• the electrical energy storage system can be easily connected to the equipment, since it includes a DC voltage busbar.
• the connection of the storage system can be made directly to the DC direct voltage busbar, or by means of a DC - DC continuous power converter with bidirectional power flow operation that is responsible for managing the loading and unloading of the storage system .
• This converter will also be used as an adapter for the DC busbar voltage to the DC voltage of the battery system.
• FIG. 2 shows the block diagram of the system proposed in this invention.
• This consists of a power converter circuit (1) and its associated control system (14) that act as an interface between an electric power generation system and the distribution grid, or simply, a dynamic stability compensator and of the frequency of the distribution network using an electrical energy storage system (capacitors (11 ') and / or batteries (11 ")) at the input.
• an electrical energy storage system capacitor (11 ') and / or batteries (11 ")
• an energy storage system based on electric accumulators to this power system, connected to the distribution network, gives this invention a very important added value, being the fundamental objective of the joint system which is claimed, the instant injection or absorption of the electrical network of the energy necessary to contribute to the improvement of its dynamic stability and the control of its frequency.
• the system can have as a storage system only electrical capacitors connected to the DC direct voltage busbar (12). In this case, the operation will be similar to the case of having batteries, except that the system, both in injection and power absorption of the power grid, will be limited to the power installed in said set of capacitors.
• the battery-based electrical energy storage system (11 ") will also be connected, which could be coupled via the DC-DC converter (15) whose mission will be to manage the loading and unloading thereof.
• Another mission of this converter (15) is to adapt the DC voltage levels between the DC busbar (12) and the storage system output (11 " ) battery based.
• the electric power generation system that acts as the main energy source can be of any type, that is, the way in which It generates electrical power at the output can be in the form of alternating voltage AC or DC continuous.
• the power installed through this type of systems be high, being able to be either a single generation system, or a set of them, so that they could be establish control strategies with the objective that all of them be seen by the distribution network as a high power generation system, with the added value of contributing as a conventional generation plant to the dynamic stability and control of the frequency of the distribution network.
• the electrical energy production system can generate, depending on its nature, alternating or continuous voltage at its output.
• generator output voltage (14 ) and, since the power system and its associated control instantly inject or absorb energy from the distribution network from a busbar of continuous, it is necessary that there is a system, also based on power electronics, that transforms this alternating voltage (AC) to DC (17) .
• This converter (17) is a rectifier circuit that can be implemented in a controlled way or uncontrolled
• a second control objective of this converter is to regulate the electrical torque of the machine (synchronous or asynchronous) (14 ") that generates the Alternate mission achieving the optimal functioning of that energy source.
• the generation of the appropriate trip sequence to achieve the control objectives described above of the rectifier circuit (17) is carried out with a control algorithm that is implemented in the microprocessor card (18) and that acquires and processes the three-phase voltages and currents at the generator output (19), in order to achieve the optimal sequence of vectors of Triggering of power switches.
• the control circuit (18) does not exist and it is necessary to add an electronic power circuit that adapts the output voltage of the uncontrolled rectifier (17) with the voltage of the continuous busbar (12).
• This circuit is a DC - DC DC voltage converter (20) whose mission is, in addition to adapting the DC voltage mentioned above, to regulate the electrical torque of the machine (synchronous or asynchronous) that generates the alternating voltage, achieving optimum operation of The source of energy. Also this power converter is controlled by a microprocessor card (21) that generates the optimal trip sequence of the power switches with the acquisition and processing of the information of the measurements of the currents and continuous voltages (22) (2T) before and after the DC DC voltage converter - DC DC (20).
• the purpose of this connection would be to store energy from the network in the electric accumulators included in the system proposed in this invention. This storage would be carried out during periods of low consumption of the power demand planning curve of the supplying electricity company, in order that the system would subsequently be able to transfer that stored energy uniformly.
• the system The object of this invention is able to contribute, in the same way as described above, to the dynamic stability and frequency control of the distribution grid.
• the main converter (1) of this invention will be used making it work as a controlled rectifier or inverter, respectively.
• the power converters (17) (20) (23) associated with such sources would be necessary.
• this system will be connected directly to the continuous busbar of the main system (12) or, by means of a system that adapts the continuous output voltage of the voltage generation system used in the continuous busbar of the main system (12).
• This circuit is a DC - DC DC power converter (23) whose mission is, in addition to adapting the DC voltage mentioned above to the input voltage of the main system power converter, to regulate the DC output current from the source Electricity generation (14 ') in order to optimize its operation.
• this power converter is controlled by a microprocessor-based card (24) that generates the optimal trip sequence of the power switches with the acquisition and processing of the continuous current and voltage measurements (25) (26) before and after the DC-DC DC voltage converter (23).
• the wind generation generates an AC alternating voltage (14 ") by means of a synchronous or asynchronous machine, which must be rectified, in a controlled or uncontrolled way, to a continuous voltage by means of the converter (17) and, depending on the application, adapted by means of a DC - DC DC voltage converter (20) to the DC bus voltage of the main system (12)
• a DC - DC DC voltage converter (20) to the DC bus voltage of the main system (12)
• an electronic power converter (23) that adapts this output voltage to the continuous busbar voltage of the main system (12) and that normally has as an additional control objective to optimize the energy capture by implementing, for the In the case of photovoltaic, the maximum power point tracking algorithm (MPPT), it should be noted that both sources can provide energy independently, both to the energy injection a instantaneously in the distribution network, such as the energy stored in the electric accumulators.
• MPPT maximum power point tracking algorithm
• the invention is characterized by including a closed loop control circuit that regulates the frequency, based on the injection or absorption of active power from the network, in order to contribute to frequency control.
• the control circuit is shown in Figure 5 where, from the three-phase network voltages, its instantaneous frequency is detected. Once the frequency is known, it is compared with the reference frequency (50 or 60 Hz) in order to obtain a frequency error. This error feeds a controller from which the active power to be injected by the power converter object of this invention is obtained. Contribution to the dynamic stability of the electricity grid
• the invention behaves from the point of view of said network as a programmable moment of inertia generator at the appropriate regulation value at the connection point of the network in which it is installed.
• the power converter object of this invention is controlled so that, in the event of a temporary power demand, for example a short circuit in the power grid, an instantaneous active power injection equivalent to which a generator would inject occurs. to the effect of inertia. The same is done in the case of the opening of an electric line that feeds the generator. In this case, the instantaneous active power equivalent to that which a generator would absorb due to the effect of mechanical inertia is absorbed.
• the calculation of the equivalent inertia power is preferably carried out by the modules (27) (41) and (42) of the block diagram shown in Figure 5. From the three-phase mains voltages, the frequency of the same instantly. Once the frequency is known, the inertia torque obtained by deriving said frequency and multiplying said derivative by a constant of inertia is calculated, this inertia pair is multiplied by the frequency to obtain the equivalent inertia power. The equivalent inertia power is subtracted from the reference power to obtain a net active power to be injected.
• the system can be connected to an isolated network being parallel to any sine-wave generating system based on synchronous machine, as is the case, for example, of a diesel generator.
• the The invention is capable of supplying the instantaneous active and reactive power necessary by causing the frequency and voltage of the isolated system to remain constant even in the event of transient short-circuit or line-opening situations, thereby contributing to the dynamic stability and regulation of the frequency and voltage of the isolated installation.
• the system object of the invention can generate a three-phase voltage waveform of constant frequency and amplitude thanks to the main power converter and the possibility of controlling said converter in voltage mode.
• the energy storage system included in the invention it is possible to inject the power evenly and according to a time schedule so that, during the operation of the system, the excess energy from the source on the energy of reference is stored in the batteries, while the power defect on the reference is provided by the batteries.
• This operation will allow the system object of the invention to inject a uniform power into the previously planned distribution network in the electricity demand curve that the supply company had contemplated for this generation plant, there being superimposed on said uniform power a ripple of active power injected or absorbed by said system, which contributes to the dynamic stability and control of the network frequency. Therefore, the system proposed in this invention injects power uniformly in the distribution network contributing to the regulation of its frequency and improving its dynamic stability.
• the invention can be connected directly to the network without the need of a power source so that, due to the reversibility of the power converters, the system can self-feed from the network itself.
• the objective is to store energy coming from the network in the set of capacitors of the DC direct voltage busbar, and in the electric accumulators included in the system proposed in this invention. This storage is carried out during periods of low consumption of the power demand planning curve of the supplying electricity company, so that the system will then be able to transfer that stored energy uniformly, fulfilling the contribution objectives to Dynamic stability and frequency regulation of the power grid.
• This form of operation allows for certain applications to dispense with the battery system, temporarily compensated with the storage or transfer to the distribution network of the energy stored in the capacitor bank. This makes the regulation capacity of this system very limited, because there is no element for generating or storing electricity in the system.
• FIG. 3 the diagrams and block diagram of a preferred embodiment of the system proposed in this invention are observed.
• This consists of a DC - alternating AC power converter circuit (1) and its associated control system (14) that acts as an interface between a wind turbine power generation system and the distribution grid.
• This embodiment consists of a storage system based on electric accumulators (11 "), directly connected to the DC voltage busbar (12) and whose loading and unloading is managed directly by the control that over the voltage of said busbar, performs the converter (1), this control being implemented in the microprocessed card (14.)
• This power system connected to the power grid, of an energy storage system, gives this invention a very important added value, being the fundamental objective of the joint system that is claimed, the injection or absorption of instantaneous active power of the distribution network in order to contribute to its dynamic stability and frequency control.
• the generator output voltage is alternating AC, and since it is necessary to adapt this AC alternating voltage to DC direct voltage, an uncontrolled rectifier circuit (30) based on a rectifier bridge of Six power diodes. It is also necessary to control the electrical torque of the machine so that the angular speed of the synchronous generator (28) of the wind turbine follows at a reference speed marked by the supervision control module (31), this speed being the suitable to optimize the capture of energy from the wind for given speed conditions.
• This machine torque control is carried out by means of the DC continuous voltage converter - DC DC (20), based on a Booster converter, which ensures that the current Output the rectifier circuit (30) follow a direct current of reference.
• This reference current is obtained in (32) a regulation implemented to minimize the error between the real angular velocity ⁇ r 0 tor (measured by the angular velocity sensor (32 ')) and the angular reference velocity ⁇ ref that It is generated in (31) with the criterion of maximizing the energy captured from the wind for any condition of the wind.
• the direct current e follows the continuous direct current by firing the IGBT of the power circuit of the Booster converter (20), following a modulation technique, such as Pulse Width Modulation (PWM).
• PWM Pulse Width Modulation
• the continuous voltage Vdc (12) of the busbar is also fed back to the control circuit (32) in order to protect said busbar from an overvoltage that would endanger the electrical energy storage systems or semiconductors of power
• the electrical machine chosen as a generator in this application (28) is synchronous, where there is an electronic circuit (34) that controls the excitation current of the rotary winding of the machine by measuring the output voltage of the Vrgen generator.
• the fundamental mission of the electronic circuit (34) is to establish the excitation curve of the synchronous generator, for which the electric machine associates a voltage in the stator of the machine based on its angular velocity. This feature is used by the control system (32) of the converter (20) to control the electrical torque of the machine.
• the main objective of this system will be to provide or store the active power necessary to contribute to the improvement of dynamic stability and the regulation of the frequency of the distribution grid. That is to say, When the electric power generation system connected to the DC DC bus input cannot provide active power instantaneously in order to compensate for the grid frequency, it will be the electrical energy storage system that performs this mission. This system will also be in charge of storing instantaneous active power coming from the network to meet the aforementioned control objectives.
• the wind turbine has been provided with an electrical energy storage system based on a set of capacitors (11 ') and a set of batteries (11 ") connected in parallel with said capacitors.
• the control over The charging and discharging of batteries is carried out directly by the main converter (1), controlling the level of the DC continuous voltage of the busbar (12) and regulating this voltage to a suitable reference voltage level for the correct operation of this converter ( 1) in the injection and absorption of instantaneous active power of the distribution network
• This control loop is implemented in the plate (14) consisting of the measurement of the DC continuous voltage of the busbar and compare it with the reference in order to generate the instantaneous active power required to meet this control objective
• Another important added value to the operation of the system proposed in this invention, provided by the electric energy storage system, is that said system will be able to inject a uniform power and in accordance with a generation time schedule that could be done on this plant in a way that, during its operation, the excess energy from the wind turbine on the reference energy will be stored in the batteries, while the energy defect on the reference will be contributed by them.
• This operation will allow inject into the distribution grid a power whose average will be equal to the reference power planned previously in the electricity demand curve that the supply company had contemplated for this generation plant.
• the control system will inject a curl of active power over the average reference power in order to contribute to the dynamic stability and frequency control of the distribution network. .
• the DC-AC power converter (1) is the main converter of this invention, which is responsible for transforming the energy stored in the capacitor bank (11 '), into the electrical storage system (11 ") and generated in the main source (29) to a sinusoidal alternating current that is injected or absorbed from the mains (13), by means of smoothing coils (35) These coils allow to control the instantaneous currents injected in each phase and reduce the curling of This system (1) behaves as a source of sinusoidal current that injects or absorbs this current from the distribution network (13), whose voltage at the connection point is fixed by the mains voltage at that point.
• this instantaneous active power injected or absorbed will allow the contr Contribution to dynamic stability and control of its frequency.
• This power will be provided instantaneously by the energy capture of the wind turbine, by the capacitors, or by the battery system, which will be able to supply the necessary active power in the absence of energy from the source, for as long as the power allows. installed power in this system. If it is necessary to absorb electrical energy to meet
• the control objectives mentioned above will be stored in the set of capacitors (11) and in the batteries (11 ").
• a microprocessor-based control system (14) is responsible for triggering the power switches of the DC-AC converter (1) connected to the mains in order to inject or absorb the active reference power Pref (figure 1) to achieve the control objectives mentioned above.
• the generation of the trip sequence of the power switches of the DC-AC converter (1) is carried out by acquiring the three-phase mains voltages, by means of the measuring transformers (36), the mains currents, by Hall effect transducers, and the continuous voltage Vdc of the busbar. All this information is processed and finally the control algorithm generates the reference current that should be injected or absorbed in each phase. These reference currents are followed by the actual output currents of the inverter by means of a Pulse Width Modulation (PWM) on the power switches of the converter (1). For the trip of these power semiconductors there is the actuator circuit (37).
• PWM Pulse Width Modulation
• Another mission of the capacitor bank connected to the DC direct voltage busbar (12) is to allow a high frequency current supply for the DC-AC converter (1) and that the power grid injection or absorption be carried out optimal way.
• microprocessor-based control system (14) which has been described above corresponding to the power converter (1) of this invention, or that necessary to adapt the wind turbine generator (32) and connect it to this system, they can be implemented in a single control card that includes several microprocessors, or only one with sufficient computing power and processing capacity that could integrate all the proposed controllers, such as a processor digital signal (DSP).
• DSP processor digital signal
• the frequency is determined instantaneously by block (9) corresponding to the calculation of the instantaneous frequency .
• the instantaneous value of the frequency (38) is known, it is compared with the reference frequency (39) to obtain the frequency error (40) and, by means of a control circuit (10), the active power to be injected (44) is calculated. to contribute to the regulation of the frequency of the network
• This power will be one of the components of the instantaneous active power injected or absorbed by the power converter object of this invention.
• the modules responsible for calculating the equivalent inertia power are included in this scheme, so that the system object of the invention behaves analogously to the large synchronous generators of conventional generation plants.
• the instantaneous frequency obtained from the frequency determination block (9) is derived and multiplied by an inertia constant J (41) in order to obtain an equivalent inertia torque.
• This equivalent inertia torque is multiplied by the instantaneous frequency in the module (42) to obtain, at the output of this module, the equivalent inertial power (43).
• the power It is the instantaneous active power that must be injected or absorbed from the power grid to contribute to the improvement of its dynamic stability.
• module (7) the sum of the following components of active power to obtain the reference instantaneous active power Pref net to be injected into the distribution network (45):
• control algorithm described above is encoded on the control card (14) of Figures 2 and 3, which corresponds to the control system of the power converter object of this invention.
• the angular reference speed is calculated by the module (31) using the instantaneous power measurement that the control system (14) performs on the network.
• the control system (31) in turn acts on the wind turbine blade angle adjustment system (47). This system is used. by the wind turbine for the following missions:
• control objectives that the supervisory system (31) pursues will be: first, and as the main characteristic claimed, the development of a control strategy on the different blocks that contribute to the dynamic stability and control of the frequency of the electricity grid of distribution, injecting or absorbing active power of said network, and as a second objective to perform an injection of active power in the uniform network in accordance with a planning of hourly power that is made on the system.
• the monitoring system (31) is implemented in a programmable automaton (PLC), which also handles the mamobras and general protections of the wind turbine system.
• PLC programmable automaton

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• 2001
  • 2001-09-13 ES ES200102062A patent/ES2190735B1/es not_active Expired - Fee Related
• 2002
  • 2002-03-06 BR BR0206033-7A patent/BR0206033A/pt not_active IP Right Cessation
  • 2002-03-06 WO PCT/ES2002/000100 patent/WO2003023933A1/es not_active Application Discontinuation
  • 2002-03-06 YU YU36003A patent/YU36003A/sh unknown

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