Energy management method and system for hybrid energy storage system in power system

Abstract

The invention discloses an energy management method for a hybrid energy storage system in a power system. The method comprises the steps of obtaining data information of a target hybrid energy storage system; performing system modeling on the target hybrid energy storage system; performing control logic modeling of the target hybrid energy storage system; and completing energy management of the target hybrid energy storage system in the power system according to the obtained modeling result. The invention also discloses a system for realizing the energy management method of the hybrid energy storage system in the power system. According to the energy management method and system for the hybrid energy storage system in the electric power system, through modeling of the hybrid energy storage system and modeling of the control logic, energy management of the hybrid energy storage system in the electric power system is achieved, an extremely accurate modeling process is not needed, reliability is higher, accuracy is better, and the method and system are suitable for popularization and application. And the efficiency is better.

Description

Technical Field

[0001] The present invention belongs to the field of electrical automation, and in particular relates to an energy management method and system for a hybrid energy storage system in an electric power system. Background Art

[0002] With the development of economy and technology and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and life, bringing endless convenience to people's production and life. Therefore, ensuring the stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] At present, environmental problems are becoming more and more serious, so more and more new energy power generation systems are being integrated into the power system to generate electricity. The output of new energy power generation systems such as solar energy and photovoltaics is random and intermittent, which increases the pressure on the safe and stable operation of the power system. The energy storage system can ensure the balance between the production and consumption of electricity in the power system, and is an indispensable part of the high-proportion new energy power system.

[0004] At present, the widely used energy storage system is the hybrid energy storage system. The hybrid energy storage system achieves the performance complementarity of energy storage equipment through multiple types of energy storage devices (such as the hybrid energy storage system of batteries + supercapacitors used in photovoltaic systems). At present, the energy management solutions of existing hybrid energy storage systems generally adopt traditional solutions such as rule-based controllers (RBC), filter-based controllers (FBC) or droop-based control (DBC) controllers. However, this type of solution is extremely sensitive to the parameter values ​​of the hybrid energy storage system and the parameter values ​​of its own control process, and its excellent control performance is based on extremely high-precision system mathematical models. However, the modeling process of extremely high-precision mathematical models is not only time-consuming and labor-intensive, but also difficult to achieve. Summary of the invention

[0005] One of the purposes of the present invention is to provide an energy management method for a hybrid energy storage system in an electric power system with high reliability, good accuracy and good efficiency.

[0006] A second objective of the present invention is to provide a system for implementing the energy management method of the hybrid energy storage system in the power system.

[0007] The energy management method of the hybrid energy storage system in the power system provided by the present invention comprises the following steps:

[0008] S1. Obtain data information of the target hybrid energy storage system;

[0009] S2. Based on the data information obtained in step S1, system modeling is performed on the target hybrid energy storage system;

[0010] S3. Based on the PI control scheme and the modeling results obtained in step S2, control logic modeling of the target hybrid energy storage system is performed;

[0011] S4. Based on the modeling results obtained in step S3, complete the energy management of the target hybrid energy storage system in the power system.

[0012] The target hybrid energy storage system specifically includes the following contents:

[0013] The target hybrid energy storage system includes photovoltaic solar panels, batteries and supercapacitors;

[0014] The photovoltaic solar panel is connected to the DC bus through a photovoltaic DC / DC converter; the battery is connected to the DC bus through a battery DC / DC converter; the supercapacitor is connected to the DC bus through a supercapacitor DC / DC converter; wherein the photovoltaic DC / DC converter is a unidirectional converter, and the battery DC / DC converter and the supercapacitor DC / DC converter are bidirectional converters;

[0015] The DC bus is connected to the AC load through a DC / AC converter.

[0016] The step S2 of performing system modeling on the target hybrid energy storage system according to the data information obtained in step S1 specifically includes the following steps:

[0017] Based on the voltage-current characteristics of photovoltaic solar panels, a photovoltaic solar panel model is constructed;

[0018] Based on the dual RC circuit, a supercapacitor model is constructed;

[0019] Construct a battery model based on the RC circuit.

[0020] The photovoltaic solar panel model is constructed based on the voltage-current characteristics of the photovoltaic solar panel, and specifically includes the following steps:

[0021] The current of photovoltaic solar panel I pv The following current characteristic expression is satisfied:

[0022] I pv =I ph -I d -I Rsh

[0023] Where I ph is the photocurrent; I d is the PN junction polarization current; I Rsh is the resistor current;

[0024] According to the voltage-current characteristics of photovoltaic solar panels, the current I pv The expression is

[0025] I pv =I SC {1-K 1 [exp(K 2 V mpv -1)]}

[0026] Where I SC is the total current of the capacitor; V mpv is the maximum power voltage of the photovoltaic array; K 1 is the first gain coefficient; K 2 is the second gain coefficient.

[0027] The supercapacitor model is constructed based on the dual RC circuit, and specifically includes the following steps:

[0028] The positive electrode of the output end of the supercapacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the first capacitor; at the same time, the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the second resistor and the second capacitor connected in series;

[0029] The first resistor and the first capacitor form a fast branch, which is used to describe the fast charge and discharge cycle process of the supercapacitor; the second resistor and the second capacitor form a slow branch, which is used to describe the internal energy distribution at the end of charging or discharging;

[0030] The voltage and current of the supercapacitor model satisfy the following formula:

[0031]

[0032] Where U sc is the voltage of the supercapacitor; N s is the number of series branches of the supercapacitor; V sc is the primary voltage of the supercapacitor; V 1 is the terminal voltage of the first capacitor, and satisfies C 1 =C 0 +C v V 1 , C 1 is the capacitance of the first capacitor, C 0 is a constant capacitance, C v is a constant parameter; R 1 is the resistance value of the first resistor; I sc is the grouping current of the supercapacitor; N p is the number of parallel branches of the supercapacitor;

[0033] The terminal voltage of the second capacitor V 2 Satisfies the following formula:

[0034]

[0035] Where C 2 is the capacitance of the second capacitor; i 2 is the current of the second capacitor, and satisfies i 1 =i sc -i 2 ,i 1 is the current of the first capacitor, i sc is the total current of the capacitor; R 2 is the resistance value of the second resistor;

[0036] The current i of the first capacitor 1 Satisfies the following formula:

[0037]

[0038] Where C V is the set constant; Q 1 is the charge of the first capacitor, and

[0039] The terminal voltage V of the first capacitor 1 satisfy

[0040] The battery model is constructed based on the RC circuit, and specifically includes the following steps:

[0041] The positive electrode of the battery is used as the output positive electrode after passing through the battery capacitor and the battery resistor connected in series; the negative electrode of the battery is used as the output negative electrode;

[0042] The voltage of the battery model V bat and current I bat Satisfies the following formula:

[0043] V bat =E 0 -R s I bat -V cvat

[0044] Where E 0 is the no-load voltage of the battery; R s is the resistance of the battery; V cvat is the voltage of the battery capacitor;

[0045] The expression of battery state of charge SOC is:

[0046]

[0047] Where Q d is the amount of charge lost, and Q d =Q d0 -I bat t, Q d0is the initial charge, t is the time; C bat is the nominal capacity of the battery, and V is the battery voltage.

[0048] The control logic modeling of the target hybrid energy storage system is performed based on the PI control scheme and the modeling result obtained in step S2, which specifically includes the following steps:

[0049] Get the actual voltage value V of the DC bus dc and the set DC bus reference voltage value V dcref ;

[0050] V dcref and V dc The difference is obtained by the first PI controller to obtain the DC bus reference current value I dcref ;

[0051] Will I dcref The battery reference current I is obtained through a low-pass filter baref , and calculate the supercapacitor reference current I scref For I scref =I dcref -I baref ;

[0052] Will I baref and I bat The difference is calculated by the second PI controller to obtain the duty cycle of the switch tube of the battery DC / DC converter;

[0053] Will I scref and I sc The difference is calculated by the third PI controller to obtain the switch duty cycle of the supercapacitor DC / DC converter.

[0054] The present invention also provides a system for implementing the energy management method of the hybrid energy storage system in the power system, comprising a data acquisition module, a system modeling module, a control modeling module and an energy management module; the data acquisition module, the system modeling module, the control modeling module and the energy management module are connected in series in sequence; the data acquisition module is used to acquire data information of the target hybrid energy storage system, and upload the data information to the system modeling module; the system modeling module is used to perform system modeling of the target hybrid energy storage system according to the received data information and the acquired data information, and upload the data information to the control modeling module; the control modeling module is used to perform control logic modeling of the target hybrid energy storage system according to the received data information, based on the PI control scheme and the obtained modeling results, and upload the data information to the energy management module; the energy management module is used to complete the energy management of the target hybrid energy storage system in the power system according to the received data information and the obtained modeling results.

[0055] The energy management method and system of the hybrid energy storage system in the power system provided by the present invention not only realizes the energy management of the hybrid energy storage system in the power system by modeling the hybrid energy storage system and the control logic, but also does not require an extremely precise modeling process, and has higher reliability, better accuracy and better efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The figure is a schematic diagram of the method flow of the present invention.

[0057] Figure 2 Schematic diagram of photovoltaic current curve of an embodiment of the method of the present invention.

[0058] Figure 3 Schematic diagram of battery current curve of an embodiment of the method of the present invention.

[0059] Figure 4 Schematic diagram of a DC bus reference current curve according to an embodiment of the method of the present invention.

[0060] Figure 5 Schematic diagram of the functional modules of the system of the present invention. DETAILED DESCRIPTION

[0061] like Figure 1 The method flow diagram of the method of the present invention is shown as follows: the energy management method of the hybrid energy storage system in the power system provided by the present invention comprises the following steps:

[0062] S1. Obtain data information of the target hybrid energy storage system; specifically including the following contents:

[0063] The target hybrid energy storage system includes photovoltaic solar panels, batteries and supercapacitors;

[0064] The photovoltaic solar panel is connected to the DC bus through a photovoltaic DC / DC converter; the battery is connected to the DC bus through a battery DC / DC converter; the supercapacitor is connected to the DC bus through a supercapacitor DC / DC converter; wherein the photovoltaic DC / DC converter is a unidirectional converter, and the battery DC / DC converter and the supercapacitor DC / DC converter are bidirectional converters;

[0065] The DC bus is connected to the AC load through a DC / AC converter;

[0066] In specific implementation, supercapacitors have fast dynamic characteristics and are used to smoothly and quickly fluctuate PV power and load in the short term (from seconds to minutes); batteries are defined as high-energy and low-power devices used to smooth the difference between PV-generated power and load demand in the long term (from minutes to hours).

[0067] S2. Based on the data information obtained in step S1, a system model is performed on the target hybrid energy storage system; specifically, the steps include:

[0068] Based on the voltage-current characteristics of photovoltaic solar panels, a photovoltaic solar panel model is constructed; specifically, the following steps are included:

[0069] The current of photovoltaic solar panel I pv The following current characteristic expression is satisfied:

[0070] I pv =I ph -I d -I Rsh

[0071] Where I ph is the photocurrent; I d is the PN junction polarization current; I Rsh is the resistor current;

[0072] According to the voltage-current characteristics of photovoltaic solar panels, the current I pv The expression is

[0073] I pv =I SC {1-K 1 [exp(K 2 V mpv -1)]}

[0074] Where I SC is the total current of the capacitor; V mpv is the maximum power voltage of the photovoltaic array; K 1 is the first gain coefficient; K 2 is the second gain coefficient;

[0075] Based on the dual RC circuit, a supercapacitor model is constructed; specifically, the following steps are included:

[0076] The positive electrode of the output end of the supercapacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the first capacitor; at the same time, the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the second resistor and the second capacitor connected in series;

[0077] The first resistor and the first capacitor form a fast branch, which is used to describe the fast charge and discharge cycle process of the supercapacitor; the second resistor and the second capacitor form a slow branch, which is used to describe the internal energy distribution at the end of charging or discharging; at the same time, the model ignores the leakage current represented by the parallel resistor during the fast charge and discharge process of the SC;

[0078] The voltage and current of the supercapacitor model satisfy the following formula:

[0079]

[0080] Where U sc is the voltage of the supercapacitor; N s is the number of series branches of the supercapacitor; V sc is the primary voltage of the supercapacitor; V 1 is the terminal voltage of the first capacitor, and satisfies C 1 =C 0 +C v V 1 , C 1 is the capacitance of the first capacitor, C 0 is a constant capacitance, C v is a constant parameter; R 1 is the resistance value of the first resistor; I sc is the grouping current of the supercapacitor; N p is the number of parallel branches of the supercapacitor;

[0081] The terminal voltage of the second capacitor V 2 Satisfies the following formula:

[0082]

[0083] Where C 2 is the capacitance of the second capacitor; i 2 is the current of the second capacitor, and satisfies i 1 =i sc -i 2 ,i 1 is the current of the first capacitor, i sc is the total capacitor current; R 2 is the resistance value of the second resistor;

[0084] The current i of the first capacitor 1 Satisfies the following formula:

[0085]

[0086] Where C V is the set constant; Q 1 is the charge of the first capacitor, and

[0087] The terminal voltage V of the first capacitor 1 satisfy

[0088] Based on the RC circuit, a battery model is constructed; specifically, the steps include:

[0089] The positive electrode of the battery is used as the output positive electrode after passing through the battery capacitor and the battery resistor connected in series; the negative electrode of the battery is used as the output negative electrode;

[0090] The voltage of the battery model V bat and current I bat Satisfies the following formula:

[0091] V bat =E 0 -R s I bat -V cvat

[0092] Where E 0 is the no-load voltage of the battery; R s is the resistance of the battery; V cvat is the voltage of the battery capacitor;

[0093] The expression of battery state of charge SOC is:

[0094]

[0095] Where Q d is the amount of charge lost, and Q d =Q d0 -I bat t, Q d0 is the initial charge, t is the time; C bat is the nominal capacity of the battery, and V is the battery voltage;

[0096] S3. Based on the PI control scheme and the modeling results obtained in step S2, control logic modeling of the target hybrid energy storage system is performed; specifically comprising the following steps:

[0097] The control logic established in this step is designed to utilize the rapid charging and discharging capabilities of the battery to reduce the battery stress caused by instantaneous power demand; the supercapacitor must be responsible for the rapid exchange of transient energy, while the battery must support the charging and discharging of energy in a relatively stable state;

[0098] Get the actual voltage value V of the DC bus dc and the set DC bus reference voltage value V dcref ;

[0099] V dcref and V dc The difference is obtained by the first PI controller to obtain the DC bus reference current value I dcref ;

[0100] Will I dcref The battery reference current I is obtained through a low-pass filter baref , and calculate the supercapacitor reference current I scref For I scref =Idcref -I baref ;

[0101] Will I baref and I bat The difference is calculated by the second PI controller to obtain the duty cycle of the switch tube of the battery DC / DC converter;

[0102] Will I scref and I sc The difference is calculated by the third PI controller to obtain the switch duty cycle of the supercapacitor DC / DC converter;

[0103] Furthermore, supercapacitors and / or batteries will ensure voltage regulation of the DC bus if there is a problem with a component;

[0104] S4. Based on the modeling results obtained in step S3, complete the energy management of the target hybrid energy storage system in the power system.

[0105] The method of the present invention is described below in conjunction with an embodiment:

[0106] Using simulation software to simulate the control effect of the method of the present invention;

[0107] During the simulation, the simulation runs for 24 seconds under different solar irradiation levels; the photovoltaic current curve is as follows Figure 2 As shown, the battery current curve is as follows Figure 3 As shown in the figure; when the photovoltaic power cannot provide the required power, the supercapacitor starts to discharge, and the SOC sc (Supercapacitor SOC value) exceeds 30%; when the power provided by the photovoltaic power is greater than the required power, the supercapacitor starts to charge, and the SOC value is also required at this time. sc Less than 90%; when SOC sc <30% and SOC bat >30%, the battery starts to discharge;

[0108] During the simulation, the voltage curve of the DC bus is as follows: Figure 4 As shown, it can be seen that the voltage of the DC bus has been stable at the expected value of around 465V, with very little fluctuation.

[0109] pass Figure 2 to Figure 4 It can be seen that the solution of the present invention has good control capability and energy management capability, and can better realize the energy management of the hybrid energy storage system in the power system.

[0110] like Figure 5The figure shows a schematic diagram of the functional modules of the system of the present invention: the system disclosed in the present invention for realizing the energy management method of the hybrid energy storage system in the power system comprises a data acquisition module, a system modeling module, a control modeling module and an energy management module; the data acquisition module, the system modeling module, the control modeling module and the energy management module are connected in series in sequence; the data acquisition module is used to acquire data information of the target hybrid energy storage system, and upload the data information to the system modeling module; the system modeling module is used to perform system modeling of the target hybrid energy storage system according to the received data information and the acquired data information, and upload the data information to the control modeling module; the control modeling module is used to perform control logic modeling of the target hybrid energy storage system according to the received data information, based on the PI control scheme and the obtained modeling results, and upload the data information to the energy management module; the energy management module is used to complete the energy management of the target hybrid energy storage system in the power system according to the received data information and the obtained modeling results.

Claims

1. An energy management method for a hybrid energy storage system in an electric power system, comprising the following steps: S1. Obtain data information of the target hybrid energy storage system; S2. Based on the data information obtained in step S1, system modeling is performed on the target hybrid energy storage system; S3. Based on the PI control scheme and the modeling results obtained in step S2, control logic modeling of the target hybrid energy storage system is performed; S4. Based on the modeling results obtained in step S3, complete the energy management of the target hybrid energy storage system in the power system.

2. The energy management method of the hybrid energy storage system in the power system according to claim 1 is characterized in that The target hybrid energy storage system specifically includes the following contents: The target hybrid energy storage system includes photovoltaic solar panels, batteries and supercapacitors; The photovoltaic solar panel is connected to the DC bus through a photovoltaic DC / DC converter; the battery is connected to the DC bus through a battery DC / DC converter; the supercapacitor is connected to the DC bus through a supercapacitor DC / DC converter; wherein the photovoltaic DC / DC converter is a unidirectional converter, and the battery DC / DC converter and the supercapacitor DC / DC converter are bidirectional converters; The DC bus is connected to the AC load through a DC / AC converter.

3. The energy management method of the hybrid energy storage system in the power system according to claim 2 is characterized in that The step S2 of performing system modeling on the target hybrid energy storage system according to the data information obtained in step S1 specifically includes the following steps: Based on the voltage-current characteristics of photovoltaic solar panels, a photovoltaic solar panel model is constructed; Based on the dual RC circuit, a supercapacitor model is constructed; Construct a battery model based on the RC circuit.

4. The energy management method of the hybrid energy storage system in the power system according to claim 3 is characterized in that The photovoltaic solar panel model is constructed based on the voltage-current characteristics of the photovoltaic solar panel, and specifically includes the following steps: The current of photovoltaic solar panel I pv The following current characteristic expression is satisfied: I pv =I ph -I d -I Rsh Where I ph is the photocurrent; I d is the PN junction polarization current; I Rsh is the resistor current; According to the voltage-current characteristics of photovoltaic solar panels, the current I pv The expression is IN pv =I SC {1-K1[exp(K2V mpv -1)]} Where I SC is the total current of the capacitor; V mpv is the maximum power voltage of the photovoltaic array; K1 is the first gain coefficient; K2 is the second gain coefficient.

5. The energy management method of a hybrid energy storage system in a power system according to claim 4, characterized in that The construction of the supercapacitor model based on the dual RC circuit specifically includes the following steps: The positive electrode of the output end of the supercapacitor is connected to one end of the first resistor, and the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the first capacitor; at the same time, the other end of the first resistor is connected to the negative electrode of the output end of the supercapacitor through the second resistor and the second capacitor connected in series; The first resistor and the first capacitor form a fast branch, which is used to describe the fast charge and discharge cycle process of the supercapacitor; the second resistor and the second capacitor form a slow branch, which is used to describe the internal energy distribution at the end of charging or discharging; The voltage and current of the supercapacitor model satisfy the following formula: Where U sc is the voltage of the supercapacitor; N s is the number of series branches of the supercapacitor; V sc is the primary voltage of the supercapacitor; V1 is the terminal voltage of the first capacitor, and satisfies C1=C0+C v V1, C1 is the capacitance of the first capacitor, C0 is a constant capacitor, C v is a constant parameter; R1 is the resistance value of the first resistor; I sc is the grouping current of the supercapacitor; N p is the number of parallel branches of the supercapacitor; The terminal voltage V2 of the second capacitor satisfies the following formula: Where C2 is the capacitance of the second capacitor; i2 is the current of the second capacitor, and i1=i sc -i2, i1 is the current of the first capacitor, i sc is the total current of the capacitor; R2 is the resistance of the second resistor; The current i1 of the first capacitor satisfies the following formula: Where C V is a set constant; Q1 is the charge of the first capacitor, and The terminal voltage V1 of the first capacitor satisfies 6. The energy management method of a hybrid energy storage system in a power system according to claim 5, characterized in that The battery model is constructed based on the RC circuit, and specifically includes the following steps: The positive electrode of the battery is used as the output positive electrode after passing through the battery capacitor and the battery resistor connected in series; the negative electrode of the battery is used as the output negative electrode; The voltage of the battery model V bat and current I bat Satisfies the following formula: V bat =E0-R s I bat -V cvat Where E0 is the no-load voltage of the battery; R s is the resistance of the battery; V cvat is the voltage of the battery capacitor; The expression of battery state of charge SOC is: Where Q d is the amount of charge lost, and Q d =Q d0 -I bat t, Q d0 is the initial charge, t is the time; C bat is the nominal capacity of the battery, and V is the battery voltage.

7. The energy management method of a hybrid energy storage system in a power system according to claim 6, characterized in that The control logic modeling of the target hybrid energy storage system is performed based on the PI control scheme and the modeling result obtained in step S2, which specifically includes the following steps: Get the actual voltage value V of the DC bus dc and the set DC bus reference voltage value V dcref ; V dcref and V dc The difference is obtained by the first PI controller to obtain the DC bus reference current value I dcref ; Will I dcref The battery reference current I is obtained through a low-pass filter baref , and calculate the supercapacitor reference current I scref For I scref =I dcref -I baref ; Will I baref and I bat The difference is calculated by the second PI controller to obtain the duty cycle of the switch tube of the battery DC / DC converter; Will I scref and I sc The difference is calculated by the third PI controller to obtain the switch duty cycle of the supercapacitor DC / DC converter.

8. A system for implementing the energy management method of a hybrid energy storage system in a power system according to any one of claims 1 to 7, characterized in that It includes a data acquisition module, a system modeling module, a control modeling module and an energy management module; the data acquisition module, the system modeling module, the control modeling module and the energy management module are connected in series in sequence; the data acquisition module is used to acquire data information of the target hybrid energy storage system and upload the data information to the system modeling module; the system modeling module is used to perform system modeling of the target hybrid energy storage system according to the received data information and the acquired data information, and upload the data information to the control modeling module; The control modeling module is used to perform control logic modeling of the target hybrid energy storage system according to the received data information, based on the PI control scheme and the obtained modeling results, and upload the data information to the energy management module; The energy management module is used to complete the energy management of the target hybrid energy storage system in the power system according to the received data information and the obtained modeling results.

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