A DC bus hierarchical response coordinated control method for a supercapacitor energy storage and micro gas turbine hybrid power generation system

Abstract

The present invention relates to a DC bus hierarchical response coordinated control method for a hybrid power generation system of supercapacitor energy storage and micro gas turbine, comprising: a micro gas turbine, a generator, a three-phase bidirectional converter, a bus capacitor, an inverter, a load, a DC converter, a supercapacitor, a three-phase converter controller and a DC converter controller. The high-power dynamic response of the supercapacitor energy storage unit compensates for the low dynamic response of the micro gas turbine output power, so that the system is in a state of instantaneous power balance in real time, ensuring the stability of the DC bus voltage and enhancing the adaptability of the micro gas turbine power generation system to pulse power loads. It can ensure the stable operation of the hybrid power generation system of supercapacitor energy storage and micro gas turbine, and improve the transient power quality of the system under impact loads. The proposed method can effectively improve the adaptability of the micro gas turbine power generation system under complex working conditions, and has great promotion and application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro gas turbine distributed power generation, and in particular relates to a DC bus hierarchical response coordinated control method for a supercapacitor energy storage and micro gas turbine hybrid power generation system. Background Art

[0002] As an important form of distributed power generation, micro gas turbines have the advantages of high power density, high reliability and low emissions. They have great application value in distributed power generation, ship power systems, drilling power and other fields.

[0003] However, micro-turbine power generation systems currently face limitations in some specialized applications. This is due to their inadequate performance, making them difficult to meet specific load requirements. Dynamic power quality under impact loads is a key bottleneck that urgently needs to be addressed. During transient conditions associated with impact loads, micro-turbine power generation systems must rapidly adjust their output power. However, the combustion mechanism of micro-turbines results in slow changes in output mechanical power, a responsiveness that fails to meet the application requirements. Impact loads can cause significant drops in the DC bus voltage, hindering the stable operation of the power conversion system and reducing output power quality. When the system experiences impact load shedding, the sudden loss of load power can lead to a significant increase in the DC bus voltage, triggering the power conversion system's fault protection mechanisms. Furthermore, the impact load reduction can cause a rapid increase in the micro-turbine speed, triggering overspeed protection and compromising reliable system operation. This, in turn, hinders the development and widespread adoption of micro-turbine power generation systems.

[0004] Currently, research on micro-turbine power generation technology focuses on the micro-turbine itself, high-speed permanent magnet synchronous generator design and control, high-speed bearings, and power conversion systems. Research on the output power quality of the micro-turbine power generation system as a whole is still relatively lacking. Although there are solutions to use batteries as starting power sources in micro-turbine power generation systems, the slow charging and discharging speeds of batteries make it difficult to cope with the requirements of impact loads, and the dynamic power quality in this situation is still poor. Supercapacitor energy storage devices have the ability to charge and discharge rapidly, making them a powerful solution for dealing with impact loads, but the structure of a micro-turbine-supercapacitor hybrid power generation system has not yet been reported. Summary of the Invention

[0005] The purpose of the present invention is to address the problem of slow output power regulation response of traditional micro-turbine power generation systems, and to propose a coordinated control method for hybrid power generation systems, based on a coordinated control algorithm of DC bus voltage graded response. The high-power dynamic response of the supercapacitor energy storage unit compensates for the problem of low dynamic response of the micro-turbine output power, so that the system is in a state of instantaneous power balance in real time, ensuring the stability of the DC bus voltage and enhancing the adaptability of the micro-turbine power generation system to pulse power loads. It can ensure the stable operation of the hybrid power generation system of supercapacitor energy storage and micro gas turbines, and improve the transient power quality of the system under impact loads. The proposed method can effectively improve the adaptability of the micro-turbine power generation system under complex working conditions, and has great promotion and application value.

[0006] A DC bus hierarchical response coordinated control method for a hybrid power generation system of supercapacitor energy storage and micro gas turbines. The system includes a micro gas turbine, a generator, a three-phase bidirectional converter, a bus capacitor, an inverter, a load, a DC converter, a supercapacitor, a three-phase converter controller, and a DC converter controller. The micro gas turbine is coaxially connected to the generator, which is connected to the three-phase bidirectional converter to convert electrical energy into DC power. The filter capacitor filters the DC power, and the inverter converts the DC power into three-phase power frequency power for the load. The DC converter is connected to the supercapacitor; the three-phase converter controller is connected to the three-phase bidirectional converter, and the DC converter controller is connected to the DC converter.

[0007] The DC bus voltage regulator of the three-phase bidirectional converter controller maintains a constant DC bus voltage v dc , the output of the regulator is i gqref1 When there is a pulse power load, in order to protect the micro gas turbine generator, it is necessary to limit the rate of change of the output power of the three-phase bidirectional converter. The rate of change limit is divided into two parts: one is the limit of the pulse power step-up process, and the other is the limit of the pulse power step-down process. e Take the differential to find the actual rate of change, and then compare it with the given value of the rate of change Compare and integrate the difference, the integration coefficient is K pe , the limiter result of the pulse power step-up process is i gqref2 , the limiter result of the step-down process is i gqref3 , the given value i of the inner current loop gqref Take i gqref1 and i gqref2 The smaller one, i gqref1 and i gqref3 The larger one, given value i when there is no pulse power load gqref with i gqref1 Equal, when there is a pulse power step increase, the given value igqref with i gqref2 Equal, when there is a pulse power step decrease, the given value i gqref with i gqref3 Equal, the current loop of the PWM rectifier is given by i gqref With maximum output power limiter.

[0008] Furthermore, the current loop of the three-phase converter is given by i gqref It can be expressed as:

[0009] i gqref =MIN{i gqref1 ,i gqref2}+MAX{i gqref1 ,i gqref3} (1)

[0010] in:

[0011]

[0012]

[0013]

[0014] Furthermore, the DC converter and the supercapacitor work together to suppress the wide range fluctuation of the DC bus voltage. The DC converter controller adopts a dual-loop structure, the inner loop is the current loop, and the outer loop is the voltage loop. The voltage loop is composed of three controllers, namely the supercapacitor voltage controller, the DC bus voltage drop prevention controller and the DC bus voltage overvoltage prevention controller. The supercapacitor voltage controller controls the supercapacitor voltage v SC To a given value v SCref The supercapacitor voltage controller adopts proportional control. When the voltage approaches the target value, the current will gradually decrease. The output of the controller is i SCref2 In order to prevent the supercapacitor from exceeding the load capacity of the micro-turbine generator when charging, the charging current has a maximum power limiter. The maximum output power of the micro-turbine generator is P recmax , the load power is P L , the difference is the maximum supercapacitor charging power P SC , the corresponding maximum charging current is i SCref1 , when the DC bus voltage v dc When there is a large drop, it exceeds the given value v dcrefL Triggering the controller action, the super capacitor can quickly output power to prevent the DC bus voltage from dropping. When the DC bus voltage v dc When there is a large lift, it exceeds the given value v dcrefH The controller is triggered to act, and the supercapacitor can quickly absorb power to prevent the DC bus voltage from rising further.

[0015] Furthermore, the final current set value of the supercapacitor energy storage power supply can be expressed as:

[0016] i SCref =-MIN{i SCref1 ,i SCref2}-i SCref3 +i SCref4 (5)

[0017] in:

[0018]

[0019]

[0020]

[0021]

[0022] The beneficial effects of the present invention are: (1) the rapid power change characteristics of the supercapacitor are used to improve the response speed of the micro gas turbine, making it adaptable to impact loads; (2) the load rate of the micro gas turbine can be effectively improved, the supercapacitor stores energy and outputs transient power changes, and the micro gas turbine outputs slowly changing power; (3) the failure rate of the micro gas turbine is reduced, and the thermal and mechanical impact of the impact load on the micro gas turbine is effectively alleviated; (4) the transient power quality output by the micro gas turbine power generation system is greatly improved. The present invention can be applied to applications with rapid power changes and has great application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural diagram of the present invention;

[0024] Figure 2 This is a block diagram of a three-phase bidirectional converter controller according to the present invention;

[0025] Figure 3 This is a control block diagram of the DC converter controller of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings.

[0027] like Figure 1As shown, the system includes a micro gas turbine 1, a generator 2, a three-phase bidirectional converter 3, a bus capacitor 4, an inverter 5, a load 6, a DC converter 7, a super capacitor 8, a three-phase converter controller 9 and a DC converter controller 10; the micro gas turbine 1 is coaxially connected to the generator 2, the generator 2 is connected to the three-phase bidirectional converter 3 to convert electrical energy into DC power, the filter capacitor 4 filters the DC power, and the inverter 5 converts the DC power into three-phase power frequency power for use by the load 6; the DC converter 7 is connected to the super capacitor 8; the three-phase converter controller 9 is connected to the three-phase bidirectional converter 3, and the DC converter controller 10 is connected to the DC converter 7;

[0028] like Figure 2 As shown, the main task of the three-phase converter controller is to maintain a constant DC bus voltage v dc This goal is achieved through PI control of the DC bus voltage, and the proportional coefficient of the controller is K dcp , the integral coefficient is K dci , the output of the controller is i gqref1 When there is a pulse power load, in order to protect the micro gas turbine generator, it is necessary to limit the rate of change of the PWM rectifier output power. The rate of change limit is divided into two parts, one is the limit of the pulse power step-up process, and the other is the limit of the pulse power step-down process. e Take the differential to find the actual rate of change, and then compare it with the given value of the rate of change Compare and integrate the difference, the integration coefficient is K pe , the limiter result of the pulse power step-up process is i gqref2 , the limiter result of the step-down process is i gqref3 , so the given value of the inner current loop i gqref Take i gqref1 and i gqref2 The smaller of the two, and i gqref1 and i gqref3 The larger one. When there is no pulse power load, the given value i gqref with i gqref1 Equal, when there is a pulse power step increase, the given value i gqref with i gqref2 Equal, when there is a pulse power step decrease, the given value i gqref with i gqref3 Equal, while the current loop of the three-phase converter is given by i gqref It also has a maximum output power limiter, and the current loop of the three-phase converter is given by i gqref It can be expressed as:

[0029] i gqref =MIN{i gqref1 ,igqref2}+MAX{i gqref1 ,i gqref3} (1)

[0030] in:

[0031]

[0032]

[0033]

[0034] Due to the effect of the limiter, when there is a pulse power load, the DC bus voltage will fluctuate in a large range. If no effective measures are taken, it will trigger the protection and shut down. The addition of supercapacitor energy storage power supply is to solve this problem. The DC converter controller also adopts a dual-loop structure, the inner loop is the current loop, and the outer loop is the voltage loop. Figure 3 As shown in the figure, the voltage loop is composed of three controllers: supercapacitor voltage controller, DC bus voltage drop prevention controller, and DC bus voltage overvoltage prevention controller. The main function of the supercapacitor voltage controller is to control the supercapacitor voltage v SC To a given value v SCref In order to avoid the adverse effects of sudden changes in charge and discharge current on the micro-turbine power supply, the supercapacitor voltage controller adopts proportional control. When the voltage approaches the target value, the current will gradually decrease. The output of the controller is i SCref2 In order to prevent the supercapacitor from exceeding the load capacity of the micro-turbine generator when charging, the charging current has a maximum power limiter. The maximum output power of the micro-turbine generator is P recmax , the load power is P L , the difference is the maximum supercapacitor charging power P SC , the corresponding maximum charging current is i SCref1 , the main function of the controller to prevent the DC bus voltage from dropping is to prevent the DC bus voltage from dropping. dc When there is a large drop, it exceeds the given value v dcrefL The controller is triggered to operate, and the supercapacitor can quickly output power to prevent the DC bus voltage from dropping and prevent the DC bus voltage from overvoltage. The main function of the controller is to prevent the DC bus voltage from overvoltage. When the DC bus voltage v dc When there is a large lift, it exceeds the given value v dcrefH The controller is triggered to act, and the supercapacitor can quickly absorb power to prevent the DC bus voltage from rising further. The final current setting value of the supercapacitor energy storage power supply can be expressed as:

[0035] i SCref =-MIN{i SCref1 ,i SCref2}-iSCref3 +i SCref4 (5)

[0036] in:

[0037]

[0038]

[0039]

[0040]

[0041] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A DC bus hierarchical response coordinated control method for a supercapacitor energy storage and micro gas turbine hybrid power generation system, characterized in that: The system comprises a micro gas turbine (1), a generator (2), a three-phase bidirectional converter (3), a bus capacitor (4), an inverter (5), a load (6), a DC converter (7), a super capacitor (8), a three-phase converter controller (9) and a DC converter controller (10); the micro gas turbine (1) is coaxially connected to the generator (2); the generator (2) is connected to the three-phase bidirectional converter (3) to convert electric energy into DC power; the filter capacitor (4) filters the DC power; the inverter (5) converts the DC power into three-phase industrial frequency power for use by the load (6); the DC converter (7) is connected to the super capacitor (8); the three-phase converter controller (9) is connected to the three-phase bidirectional converter (3); and the DC converter controller (10) is connected to the DC converter (7); The DC bus voltage regulator of the three-phase bidirectional converter controller (9) is used to maintain a constant DC bus voltage v dc , the output of the regulator is i gqref1 When there is a pulse power load, in order to protect the micro gas turbine generator, it is necessary to limit the rate of change of the output power of the three-phase bidirectional converter (3). The rate of change limit is divided into two parts, one is the limit of the pulse power step-up process, and the other is the limit of the pulse power step-down process. The output power P of the three-phase bidirectional converter (3) is e Take the differential to find the actual rate of change, and then compare it with the given value of the rate of change Compare and integrate the difference, the integration coefficient is K pe , the limiter result of the pulse power step-up process is i gqref2 , the limiter result of the step-down process is i gqref3 , the given value i of the inner current loop gqref Take i gqref1 and i gqref2 The smaller one, i gqref1 and i gqref3 The larger one, given value i when there is no pulse power load gqref with i gqref1 Equal, when there is a pulse power step increase, the given value i gqref with i gqref2 Equal, when there is a pulse power step decrease, the given value i gqref with i gqref3 Equal, the current loop of the PWM rectifier is given by i gqref With maximum output power limiter; The DC converter (7) and the supercapacitor (8) work together to suppress the wide range fluctuation of the DC bus voltage. The DC converter controller (10) adopts a double-loop structure, the inner loop is a current loop, and the outer loop is a voltage loop. The voltage loop is composed of three controllers, namely a supercapacitor voltage controller, a controller for preventing the DC bus voltage from dropping, and a controller for preventing the DC bus voltage from overvoltage. The supercapacitor voltage controller controls the supercapacitor voltage v SC To a given value v SCref The supercapacitor voltage controller adopts proportional control. When the voltage approaches the target value, the current will gradually decrease. The output of the controller is i SCref2 In order to prevent the supercapacitor from exceeding the load capacity of the micro-turbine generator when charging, the charging current has a maximum power limiter. The maximum output power of the micro-turbine generator is P recmax , the load power is P L , the difference is the maximum supercapacitor charging power P SC , the corresponding maximum charging current is i SCref1 , when the DC bus voltage v dc When there is a large drop, it exceeds the given value v dcrefL Triggering the controller action, the super capacitor can quickly output power to prevent the DC bus voltage from dropping. When the DC bus voltage v dc When there is a large lift, it exceeds the given value v dcrefH The controller is triggered to act, and the supercapacitor can quickly absorb power to prevent the DC bus voltage from rising further.

2. The DC bus hierarchical response coordinated control method of a supercapacitor energy storage and micro gas turbine hybrid power generation system according to claim 1 is characterized in that: The current loop of the three-phase bidirectional converter is given by i gqref It can be expressed as: i gqref =MIN{i gqref1 ,i gqref2 }+MAX{i gqref1 ,i gqref3 } (1) in:

3. The DC bus hierarchical response coordinated control method of a supercapacitor energy storage and micro gas turbine hybrid power generation system according to claim 1 is characterized in that: The final current set value of the supercapacitor energy storage power supply can be expressed as: in SCref =-MIN{i SCref1 ,in SCref2 }-in SCref3 +i SCref4 (5) in:

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