CN105098786A - System and method for stabilizing voltage fluctuation of wind power micro-grid employing super capacitors - Google Patents

Abstract

A method for using supercapacitors to stabilize voltage fluctuations in wind power microgrids. The present invention relates to the technical field of microgrids and wind power generation, in particular to the use of supercapacitors in wind power microgrids to stabilize wind power, and mainly applies the voltage in microgrids composed of wind power systems fluctuations are suppressed. The invention provides the specific principle and system structure diagram of applying supercapacitors to stabilize the voltage fluctuations of wind power microgrids. The system consists of wind power generation units, capacitance compensation devices, supercapacitor banks, bidirectional DC/DC converters, voltage source inverters and filter circuit composition. As the supercapacitor energy storage unit and the DC bus interface, the buck-boost bidirectional DC/DC converter structure is analyzed. Through PWM control, the duty cycle of T1 and T2 switches is changed to realize the supercapacitor charge and discharge control. The DC/DC converter is controlled by a double-closed-loop control strategy of the voltage outer loop and the current inner loop, and the specific control method of the supercapacitor bank for power exchange is given.

Description

A system and method for supercapacitors to stabilize voltage fluctuations in wind power microgrids

technical field

The invention relates to the technical fields of micro-grid and wind power generation, in particular to a system and a method thereof for a supercapacitor to stabilize the voltage fluctuation of a wind power micro-grid.

Background technique

Wind power has become the most competitive renewable energy due to its cleanliness and non-pollution. However, wind power is easily affected by external factors such as changes in wind speed, and the output power has volatility and randomness, which affects the reliability of wind power output, and the power quality needs to be further improved. Especially with the further increase of wind power penetration rate, the impact of wind power on microgrid cannot be ignored. Installing supporting energy storage equipment and adopting certain energy storage control strategies can effectively stabilize wind power fluctuations and improve the quality of microgrid power supply. Since the supercapacitor energy storage device has high power density, long cycle life, fast release capability, fast power throughput and response speed, it has become an effective means to quickly stabilize wind power fluctuations.

Contents of the invention

The purpose of the present invention is to provide a method for using a supercapacitor to stabilize the voltage fluctuation of a wind power microgrid.

A supercapacitor system for suppressing voltage fluctuations in wind power microgrids, the system consists of a wind power generation unit, a capacitance compensation device, a supercapacitor bank, a bidirectional DC/DC converter, a voltage source inverter and a filter circuit; the system includes a buck-boost Bidirectional DC/DC converter, supercapacitor bank energy storage unit is connected to the DC bus, T1 and T2 are full-control switching devices, D1 and D2 are anti-parallel freewheeling diodes, through PWM control, the switching tubes of T1 and T2 are changed Duty cycle, so as to realize the charge and discharge control of the supercapacitor.

The system controls the converter through the double-closed-loop control strategy of the converter voltage outer loop and the current inner loop. The reference voltage V _ref is compared with the converter output voltage V _DC and sent to the voltage PI regulator to obtain the high-voltage side current control signal. I _HV , the signal is processed by the signal operation mechanism to obtain the reference current signal I _ref , which is compared with the measured current signal I _DC of the supercapacitor, sent to the current PI regulator, and the output signal is turned on and off for T1 and T2 through the PWM controller control.

The system gives the control method of supercapacitor bank for power exchange. When the output power of wind power is greater than the given power, the supercapacitor bank is charged, and the bidirectional DC/DC converter works in the step-down chopper circuit mode. When the output power of wind power is insufficient , when it is less than the given power of the system, the supercapacitor bank is discharged, and the bidirectional DC/DC converter works in the boost chopper circuit mode.

Description of drawings

Fig. 1 The system structure diagram of applying supercapacitor to stabilize the voltage fluctuation of wind power microgrid;

Fig. 2 The structure diagram of buck-boost bidirectional DC/DC converter;

Fig. 3. Structure diagram of control strategy of bidirectional DC/DC converter.

Detailed ways

In order to enable those engaged in the related fields of wind power generation and energy storage technology to better understand the solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The structure diagram of the system for the supercapacitor to stabilize the voltage fluctuation of the wind power microgrid is shown in Figure 1. The system consists of a wind power generation unit, a capacitance compensation device, a supercapacitor bank, a bidirectional DC/DC converter, a voltage source inverter and a filter circuit . Assuming that the wind power micro-grid system is running stably, the wind power unit and the supercapacitor energy storage unit jointly inject power into the external grid, and the active and reactive power are respectively P _ref and Q _ref . When affected by wind speed or external factors, the wind power output is Active power P _WIND , reactive power Q _WIND , supercapacitor energy storage for fast compensation, the output active power is P _ref -P _WIND , and reactive power is Q _ref -Q _WIND , then from the perspective of the external power grid, the injected power remains unchanged, so that it can Maintain system power balance and maintain voltage stability.

The supercapacitor energy storage unit and the DC bus interface adopt a buck-boost bidirectional DC/DC converter. As shown in Figure 2, T1 and T2 are fully-controlled switching devices, and D1 and D2 are anti-parallel freewheeling diodes, which are controlled by PWM , change the duty cycle of the T1 and T2 switch tubes, so as to realize the charge and discharge control of the supercapacitor. The DC/DC converter adopts the control strategy shown in Figure 3, and controls the converter through the double-closed-loop control strategy of the converter voltage outer loop and current inner loop. The reference voltage V _ref is compared with the converter output voltage V _DC and sent to The voltage PI regulator obtains the high-voltage side current control signal I _HV , and the signal is processed by the signal operation mechanism to obtain the reference current signal I _ref , which is compared with the supercapacitor current signal I _DC and sent to the current PI regulator for PWM control The device, the output signal carries on the on-off control to T1, T2. When the output power of wind power is greater than the given power, the supercapacitor bank is charged, and the bidirectional DC/DC converter works in the step-down chopper circuit mode. When the output power of wind power is insufficient and less than the given power of the system, the supercapacitor bank is discharged. The bidirectional DC/DC converter works in the step-up chopper circuit mode.

A supercapacitor system for suppressing voltage fluctuations in wind power microgrids, the system consists of a wind power generation unit, a capacitance compensation device, a supercapacitor bank, a bidirectional DC/DC converter, a voltage source inverter and a filter circuit; the system includes a buck-boost Bidirectional DC/DC converter, supercapacitor bank energy storage unit is connected to the DC bus, T1 and T2 are full-control switching devices, D1 and D2 are anti-parallel freewheeling diodes, through PWM control, the switching tubes of T1 and T2 are changed Duty cycle, so as to realize the charge and discharge control of the supercapacitor.

The system controls the converter through the double-closed-loop control strategy of the converter voltage outer loop and the current inner loop. The reference voltage V _ref is compared with the converter output voltage V _DC and sent to the voltage PI regulator to obtain the high-voltage side current control signal. I _HV , the signal is processed by the signal operation mechanism to obtain the reference current signal I _ref , which is compared with the measured current signal I _DC of the supercapacitor, sent to the current PI regulator, and the output signal is turned on and off for T1 and T2 through the PWM controller control.

The system gives the control method of supercapacitor bank for power exchange. When the output power of wind power is greater than the given power, the supercapacitor bank is charged, and the bidirectional DC/DC converter works in the step-down chopper circuit mode. When the output power of wind power is insufficient , when it is less than the given power of the system, the supercapacitor bank is discharged, and the bidirectional DC/DC converter works in the boost chopper circuit mode.

Referring to Figure 1, this system provides a structural diagram of a system that uses supercapacitors to stabilize the voltage fluctuations of wind power microgrids. The system consists of wind power generation units, capacitance compensation devices, supercapacitor banks, bidirectional DC/DC converters, and voltage source inverters. and filter circuit.

Referring to Figure 2, this system provides a structure diagram of a buck-boost bidirectional DC/DC converter to realize the connection between the supercapacitor energy storage unit and the DC bus. The freewheeling diodes connected in parallel can change the duty cycle of T1 and T2 switching tubes through PWM control, so as to realize the charge and discharge control of the supercapacitor.

Referring to Figure 3, this system provides a structure diagram of the DC/DC converter control strategy. The converter is controlled through the double closed-loop control strategy of the converter voltage outer loop and the current inner loop, and the reference voltage V _ref and the converter output voltage V _DC are controlled. Comparison, sent to the voltage PI regulator to obtain the high-voltage side current control signal I _HV , the signal is processed by the signal operation mechanism to obtain the reference current signal I _ref , compared with the supercapacitor current signal I _DC , and sent to the current PI regulator , through the PWM controller, the output signal performs on-off control on T1 and T2. The PI regulator in the system should select proportional and integral parameters according to the system, and the relevant voltage and current signals can be obtained through the detection device.

The above content is a detailed description of the present invention in conjunction with the preferred technical solutions. It cannot be determined that the specific implementation of the invention is limited to these. Simple deduction and replacement made without departing from the idea of the present invention should be regarded as protection of the present invention. scope.

Claims (3)

1. ultracapacitor stabilizes a wind-powered electricity generation micro-capacitance sensor voltage fluctuation system, it is characterized in that: this system is made up of wind power generation unit, Electric capacity compensation device, bank of super capacitors, two-way DC/DC converter, voltage source inverter and filter circuit; This system comprises the two-way DC/DC converter of buck, bank of super capacitors energy-storage units is connected with DC bus, T1, T2 are full-controlled switch device, D1, D2 are antiparallel fly-wheel diode, controlled by PWM, change the duty ratio of T1, T2 switching tube, thus realize the charge and discharge control of ultracapacitor.

2. ultracapacitor stabilizes a wind-powered electricity generation micro-capacitance sensor voltage fluctuation method, it is characterized in that: this system is carried and carried out current transformer control by converter voltage outer shroud and current inner loop double-loop control strategy, reference voltage V _refwith converter output voltage V _dCcompare, send into voltage PI regulator, obtain high voltage side current control signal I _hV, this signal, through the process of signal operation mechanism, obtains reference current signal I _ref, and ultracapacitor measured current signal I _dCcompare, send into current PI adjuster, by PWM controller, output signal and break-make control is carried out to T1, T2.

3. a kind of ultracapacitor according to claim 1 stabilizes wind-powered electricity generation micro-capacitance sensor voltage fluctuation method, it is characterized in that: system gives the control mode that bank of super capacitors carries out Power Exchange, when wind power output power is greater than given power, bank of super capacitors is charged, two-way DC/DC converter is operated in buck circuit pattern, when wind power output power is not enough, when being less than the given power of system, bank of super capacitors is discharged, and two-way DC/DC converter is operated in boost chopper pattern.