BG110743A - A system for output power control of a wind energy conversion system - Google Patents

Abstract

The system is applicable in the wind energy engineering. The system is an active electrical system for control of the output power in wind energy conversion systems (WECS) within the range of the power curve after its maximum. This is that part of the curve, which corresponds to a higher turbine rotor (1) rotation speed. In this way the electric energy system operator may precisely regulate the power delivered to the network, without interrupting the work of the wind generator (without switching it out), and is secured effective operation of the EE system, even at high WECS concentration. Thesystem contains a turbine (1), electricity generator (2), converter (5), device for energy stockpiling (6), as well a control device (7).

Description

Technical field

The invention relates to a system for controlling the output power of an electric generator in a wind energy conversion system (HPP) and will find application in wind power.

BACKGROUND OF THE INVENTION

In order to increase the efficiency of the HPP and to improve its integration into the transmission network, it is necessary to control the input mechanical power and / or the output electrical power. This is accomplished through various systems, commonly known as the Maximum Power Point Tracking Systems (STMM systems).

The main purpose of STMM systems is to derive the maximum wind power available at different wind profiles and speeds. To achieve this, two different types of control systems are applied: a) control the angle of attack of the blades of the turbine and b) control the electromagnetic torque of the generator.

(A) Increasing the absorbed inlet mechanical power at low wind speeds (4-10 m / s) or reducing the inlet mechanical power at very high wind speeds (over 16-18 m / s) is achieved. This strategy is primarily used to protect the turbine from mechanical damage (blade tearing) at high wind speeds, and to synchronize power performance for different wind turbines, where conditions for different wind turbines can vary significantly. . Input power STMM systems can be a combination of hydraulic and power units that rotate the gondola and the blades of the wind turbine at different angles of attack, according to a control unit assignment that takes into account the variation of several different wind parameters as speed and direction.

When controlling the generator's electromagnetic torque, the STMM system b) maintains a given generator's electromagnetic torque at which maximum power is extracted. The torque is controlled by electronic converters. The STTM system consists of an electrical system that controls the generator current through a controller that monitors predetermined power curves for a particular turbine and determines the maximum point of these curves at a given wind speed.

Due to the increasing concentration of wind turbines, there are certain problems with the control of the power delivered to the electricity system, for example: maintenance of voltage and frequency, load management, synchronization of the operation of wind turbines in the wind power plant, etc. To overcome these problems, it is necessary to actively manage HPP in terms of the power that is allocated to the network.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an electrical system for actively controlling the output of HPP in the power curve range after its maximum. This is the part of the curve that corresponds to a higher rotation speed of the turbine rotor. This allows the electricity system operator to regulate the power output precisely without interrupting the operation of the wind generator (without disconnecting it from the grid) and without using the energy storage device (UE) (due to lack of spare capacity) for storage or due to dysfunctionality) and the efficient operation of the electricity (EE) system is ensured even at high concentrations of HPP. It also provides the ability to actively control the power output to the ultrasound, while maintaining a specific charge and discharge cycle.

The wind energy conversion system (Fig. 1) consists of a wind turbine (1) and an electric generator (2). It is connected to the electrical network (3) by a control system consisting of an AC-DC converter (4) whose AC terminals are connected to the generator (2) and the DC terminals are connected to a DC-AC converter (5 ), which provides the connection to the power grid (3) and to the energy storage device (6), which may be rechargeable batteries, supercapacitors, mini solar panels, rotary tables, superconducting electromagnetic device (SMES) or a combination of these devices. The last element of the control system is the control unit (7), which is connected to the electric generator (2), to the electronic converters (4) and (5) and to the energy storage device (6).

The control unit (7) consists of a sensor unit connected to a control unit for determining the power reference, to the mode selector unit and to regulators. The output of the mode selection block is connected to the control block. The output of the control unit is connected to the input of the regulators. The outputs of the regulators are connected to the modulators whose outputs are connected to the electronic converters (4) and (5) and to an energy storage device (6). The system operator job is submitted to the mode selection block.

The control unit receives information about the current state of the system (current, DC voltage, electromagnetic torque, rotor speed, wind speed, etc.) via the sensor block. Based on the state of the energy storage device and the system operator's power reference, the operating mode of the mode selector is selected. Two operating modes of the control system are possible: a) standard mode in which the maximum power is sought regardless of the wind speed (STMM mode) and b) limited mode in which the power is demanded according to the EE system operator specified permissible limit for transmitting to the power grid below the maximum and / or according to the restricted mode of operation of the SLM (STOM). According to the set criteria for the positioning of the operating point, the control unit produces an assignment for the power delivered by the HPP in the network. Regulators, for their part, compare the reference values of the controlled quantities with their instantaneous values, and through the modulators control the converters of the electric generator (4) and (5) and of the energy storage device (6).

The advantages of the system according to the invention lie in the ability to control the output power in a wind energy conversion system in order to limit it, according to EE system operator and / or USE conditions. Such conditions may be high wind speeds or the inability of the energy system and the ultrasound to absorb the maximum electrical power from the HPP. This prevents the wind turbine from being switched off immediately and extends its operation, which is associated with economic benefits for the HPP owner without disturbing the balance of the EE network and / or the unconnected consumer. All this is achieved electrically without the use of sophisticated mechanical power management systems that increase cost, reduce reliability and lead to higher operating costs.

Description of the accompanying drawings

Figure 1 is a block diagram of the HPP power output control system;

Figure 2 is a schematic diagram of a HPP power output control system whose control device uses built-in STOM curves;

Figure 3 is a schematic diagram of a HPP power output control system whose control device uses a fuzzy STOM logic;

Figure 4 is a family of power curves for a particular type of turbine at different wind speeds and the STOM zones are indicated;

Examples of carrying out the invention

As shown in FIG. 1 configuration, an output power management system can use two different types of STOM control devices: a) a control device that uses pre-calculated power curves and, through mathematical methods of interpolation, calculates the specific power value that satisfies the operating mode (Fig. 2) and b) a control device that uses fuzzy logic to determine the desired output power (Fig. 3).

In the first case (Fig. 2), a specific family of mechanical power characteristics is determined for a particular type of turbine as a function of the rotor speed and the wind speed (Fig. 4). These characteristics define different points on the right-hand side of the curves at which the power is less than the maximum. These points define the areas of operation of the VEPS in the restricted mode and are connected by approximation in separate curves at different wind speeds. These curves are stored in the control unit and used by the control unit, which by interpolation calculates the power setting of the VPS.

Advantages: speed; high precision work.

Disadvantages: complicated sensor block; need to know the detailed technical characteristics of the turbine.

In the second case (Fig. 3), an "intuitive" definition of the power reference is used by means of two input signals (output electric power and turbine speed) and fuzzy logic methods. Defining fuzzy logic requires knowledge of the shape of the wind turbine's power curve and compiling a table is a sequence of (if-else) actions that calculate the power reference to meet the STOM mode that is being used. records in the control unit.

Advantages: analytical method that does not require knowledge of the technical characteristics of the turbine;

Disadvantages: slower action and reduced accuracy with fast wind speed changes.

For both types of control unit, it is possible to operate in STMM mode in case of demand for operation with maximum turbine efficiency.

Claims (7)

Claims 1. Wind power converter output control system in limited power point monitoring mode comprising an AC-DC electronic converter (4), the AC terminals of which are connected to the electric generator (2) and the DC terminals are connected to DC-AC converter (5), which provides the connection to the mains (3) and to an energy storage device (6). The last element of the control system is the control unit (7), which is connected to the electric generator (2), to the electronic converters (4) and (5) and to the energy storage device (6). The control unit (7) consists of a sensor unit connected to a control unit for determining the power reference, to the mode selector unit and to regulators. The output of the mode selection block is connected to the control block. The output of the control unit is connected to the input of the regulators. The outputs of the regulators are connected to the modulators whose outputs are connected to the electronic converters (4) and (5) and to the energy storage device (6). The system operator job is submitted to the mode selection block. System according to claim 1, characterized in that the control device uses previously known mechanical power curves with limited wind turbine power to monitor the limited power point. System according to claim 1, characterized in that the control device uses the nominal power curve of the wind turbine to monitor the point of limited power. The system of claim 1, characterized by the use of: batteries, supercapacitors, mini solar panels, rotary tables, superconducting electromagnetic device (SMES) or a combination of the above elements in the energy storage device. Power management system for wind power conversion system Field of application of the present invention is wind power. Due to the increasing concentration of wind energy conversion systems (HPP), there are certain problems with integrating them into the electricity system, such as: maintaining voltage and frequency, load management, synchronizing the operation of wind turbines in a wind farm, etc. In order to prevent, active management of HPPs is required in terms of the power delivered to the network and / or consumers. It is an object of the present invention to provide an active electrical system for controlling the output of HPP in the power curve range after its maximum. This is the part of the curve that corresponds to a higher rotation speed of the turbine rotor. This allows the electricity system operator to precisely regulate the power delivered to the grid without interrupting the operation of the wind generator (without switching off) and to ensure efficient operation of the EE system even at high concentrations of HPP. Attachment: 4 figures 1. Wind turbine; 2. Electric generator; 3. Electric network; 4. AC-DC electronic converter; 5. DC-AC electronic converter; 6. Energy storage device (batteries, supercapacitors, mini solar panels, rotary tables, superconducting electromagnetic device (SMES)); 7. Control device;