CN108009387A - A kind of compound energy analogue system and management strategy - Google Patents

Abstract

The invention discloses a multi-energy compound power supply energy simulation system and an energy system management strategy, which realizes the output characteristic curve simulation of each energy harvester simulation sub-module for evaluating its energy output capability. It can be used as a reference in the design of the composite energy system to optimize the performance of each energy harvester; in addition, it can realize the transient simulation of the overall working state of the system. The simulation is carried out according to the specified energy management strategy, which can evaluate the overall system during operation stability and loading capacity. Furthermore, realizing the optimization of the management strategy and the performance coordination of each device in the composite energy system can improve the development efficiency of the composite energy system.

Description

A Composite Energy Simulation System and Management Strategy

technical field

The present invention relates to composite energy technology, specifically, the control technology field of composite power supply composed of vibration energy collectors, solar cells, fuel cells, lithium batteries and super electric appliances.

Background technique

Whether it is in industrial applications, the wireless sensor network composed of large-scale wireless sensor nodes has a very wide range of applications in the field of monitoring and sensing. Traditional wireless sensor nodes mostly use a single chemical power source to drive the node's controller and transmitter to work. Ordinary chemical batteries are consumables with limited power and discharge time, and due to their own leakage, their stability and reliability under long-term working conditions are low.

The actual application environment of wireless sensor network generally has solar energy and vibration mechanical energy. If it is possible to collect solar energy during the day, collect vibration energy at night or under low-light conditions, and accumulate and store these two kinds of energy, it can effectively drive the work of the sensing node.

Existing electronic equipment usually uses solar cells as a single form of external energy to provide power for the equipment, and uses the only lithium battery as an energy storage unit. Although the energy supply of a single energy source has a simple structural design, there are many uncertainties in the energy in the environment. The energy system of a single energy source is highly dependent on the environment. If the working environment changes, the stability and applicability of the energy source may be greatly reduced. On the other hand, the use of traditional battery technology has the problems of low energy density and limited life. For large-area unattended sensors, it is very difficult to replace the battery.

In this environment, a composite energy system emerged as the times require. The composite energy system is an energy system that integrates energy devices such as vibration energy harvesters, solar cells, fuel cells, and lithium batteries to provide stable, high-speed energy for wireless sensor nodes. Lifetime energy supply. From the perspective of energy, the composite energy system can be divided into three components:

1) Environmental energy source collection part

Refers to the harvesting of energy from the environment through energy harvesting technologies such as solar cells, wind turbines, and piezoelectric generators.

2) load

It refers to the wireless sensor node electronic system supported by the composite energy system. Its energy consumption depends on the specific working mode of wireless sensor nodes. For example, for a self-powered wireless sensor node, the load of its electronic system depends on the workload and work level of the self-powered wireless sensor network application layer, and also depends on the specific work done by the node in the distributed network.

3) Energy management strategy

It means that when the instantaneous energy collected from the environment does not match the energy consumption level of the load, the composite energy system can make changes according to different situations to meet the balance between output and load.

The composite energy system needs to manage a variety of different energy collection/energy storage methods, and realize complementary advantages by taking advantage of each other's strengths, and ultimately prolong the service life of the system. This puts forward higher requirements for the overall design and performance optimization of the composite energy system. Therefore, it is necessary to establish a corresponding system model for the composite energy system for simulation, evaluate the performance of the energy harvester, and provide design reference for the management strategy of the composite energy system. Most of the similar system models in the prior art are for a certain type The verification model of the energy system, whose working mode, structure, and attribute parameters have been determined, lacks guidance for the design of management strategies.

Contents of the invention

Aiming at the defects existing in the prior art, the present invention provides a multi-energy compound power supply energy simulation system, the simulation system can analyze and evaluate each energy collection and storage situation; and can simulate the system as a whole in operation The operating status of the module is used to evaluate the energy management strategy, and finally realize the design optimization process of the composite energy system through the evaluation of the two aspects, and increase the efficiency of research and development.

Concrete scheme of the present invention is as follows:

A composite energy simulation system, said system comprising:

The energy harvesting simulation module is used to describe and simulate the relationship between the external energy input and electric energy output of the energy harvesting module in the composite energy system;

The energy management simulation module is used to describe the basic logical relationship of the energy management algorithm strategy in the composite energy system and simulate it;

The energy storage simulation module is used to describe and simulate the power input and output relationship of the energy storage module in the hybrid energy system;

The load simulation module is used to describe the power demand of the external power load in the working process of the composite energy system, so as to generate the external input required for the simulation of the composite energy system.

Further, the energy harvesting simulation module includes:

The solar cell simulation sub-module is used to describe the relationship between the illumination conditions of the solar cell and its output power curve in the energy harvesting simulation module, and to simulate it;

The vibration energy harvester simulation sub-module is used to describe the relationship between the external environment vibration conditions of the vibration energy harvester and its output power curve in the energy harvesting simulation module, and to simulate it;

The fuel cell simulation sub-module is used to describe the relationship between the fuel supply of the fuel cell in the energy harvesting simulation module and its output power curve, and simulate it;

The solar cell simulation sub-module, the vibration energy harvester simulation sub-module, and the fuel cell simulation sub-module are all equivalent circuit building models, and the generated current is calculated according to a certain working voltage.

Further, the solar cell simulation sub-module, the vibration energy harvester simulation sub-module, and the fuel cell simulation sub-module are all equivalent circuit building models, and the generated current is calculated according to a certain working voltage.

Further, the energy storage simulation module is established according to the PNGV model of the lithium-ion battery, and the remaining power and the voltage value of the energy storage simulation module are calculated according to the current flowing in/out of the port at all times.

Further, the energy management simulation module can provide working voltage parameters for the energy harvesting simulation module, calculate the port current of the energy storage simulation module according to the set energy management strategy, and output the operating status of the simulation system.

Further, the load simulation model provides voltage and current parameters required by the load for the energy management simulation module model.

In addition, the present invention also discloses a management strategy applied to a composite energy simulation system, which includes the following steps:

Step 1) Obtain the voltage and current parameters of the load demand from the load simulation module;

Step 2) Obtain the current energy storage simulation module voltage from the energy storage simulation module;

Step 3) providing the initial value of the operating voltage parameter for the energy harvesting simulation module;

Step 4) Select whether to cut off the current output of a certain sub-module according to the output current of the energy harvesting simulation module;

Step 5) Calculate the port current of the energy storage simulation module according to the output power of the energy harvesting simulation module and the current and voltage requirements of the load simulation module;

Step 6) judging the current working state of the system and outputting it;

Step 7) Update the operating voltage parameters for the energy harvesting simulation module.

Further, the current parameters are set to be positive for inflow and negative for outflow.

Further, the calculation in step 5) adopts the principle of power balance.

Further, steps 1-7) are performed iteratively at each time point, so as to realize transient simulation.

Further, judging the current working state of the system in step 6) includes: judging whether the energy harvesting simulation sub-module has an effective output based on the system power balance criterion, estimating the remaining power parameters of the energy storage simulation module based on the state of charge estimation algorithm, etc., based on The power curve of each simulation sub-module judges whether the energy system can meet the load demand.

The multi-energy composite power supply energy simulation system disclosed in the present invention can analyze and evaluate each energy collection and storage module; and can simulate the operating status of each module during the operation of the system as a whole to evaluate the energy management strategy, and finally Through the evaluation of the two aspects, the design optimization process of the composite energy system is realized, and the research and development efficiency is increased.

Description of drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention, in the accompanying drawings :

Fig. 1 shows the structure diagram of the multi-energy compound power supply energy simulation system in the embodiment of the present invention;

Fig. 2 shows a flow chart of the system management policy in the embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the invention.

Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. The suffixes "module" and "unit" of elements are used here for convenience of description, and thus may be used interchangeably without any distinguishable meaning or function.

Although all elements or units constituting an embodiment of the present invention are described as being incorporated into a single element or operated as a single element or unit, the present invention is not necessarily limited to such an embodiment. According to the embodiment, all elements within the purpose and scope of the present invention may be selectively coupled to and operated as one or more elements.

Fig. 1 has provided the composite energy simulation system architecture diagram in the embodiment of the present invention; As shown in the figure, 1 is the energy harvesting simulation module, wherein 2, 3, 4 are vibration energy harvester simulation sub-modules respectively, and solar cell simulation sub-module module, a fuel cell simulation sub-module, 5 is an energy storage simulation module, in particular, a lithium-ion battery energy storage simulation module; 6 is a load simulation model, and 7 is an energy management simulation module.

Among them, the energy harvesting simulation module is used to describe and simulate the relationship between the external energy input and electric energy output of the energy harvesting module in the composite energy system;

The energy management simulation module is used to describe the basic logical relationship of the energy management algorithm strategy in the composite energy system and simulate it;

The energy storage simulation module is used to describe and simulate the power input and output relationship of the energy storage module in the hybrid energy system;

The load simulation module is used to describe the power demand of the external power load in the working process of the composite energy system, so as to generate the external input required for the simulation of the composite energy system.

The energy harvesting simulation module includes: a solar cell simulation sub-module, which is used to describe the relationship between the illumination conditions of the solar cell in the energy harvesting simulation module and its output power curve, and to simulate it;

The vibration energy harvester simulation sub-module is used to describe the relationship between the external environment vibration conditions of the vibration energy harvester and its output power curve in the energy harvesting simulation module, and to simulate it;

The fuel cell simulation sub-module is used to describe the relationship between the fuel supply of the fuel cell in the energy harvesting simulation module and its output power curve, and simulate it;

The solar cell simulation sub-module, the vibration energy harvester simulation sub-module, and the fuel cell simulation sub-module are all equivalent circuit building models, and the generated current is calculated according to a certain working voltage.

In one embodiment, the solar cell simulation sub-module is realized by an equivalent circuit model of a solar cell, which will produce different output characteristics in response to changes in external lighting conditions; the vibration energy harvester simulation sub-module is composed of an electromechanical coupling model and an equivalent circuit model In the calculation, the collected charge is firstly calculated by the classical electromechanical coupling model of the cantilever beam piezoelectric vibration energy harvester, and then the output characteristics are calculated by the RC equivalent circuit. This module will obtain different outputs under different external excitation conditions. characteristics; the fuel cell simulation sub-module uses a hydrogen-oxygen fuel cell model based on the Nernst equation for calculation. For a certain set hydrogen-oxygen fuel flow rate and pressure, a set of fixed output characteristics will be generated. The above model establishment methods are Belong to prior art.

In the first stage of the simulation system operation, these energy harvesting simulation modules are first initialized and parameterized. After setting the attribute parameters and external conditions, the output V-I characteristics of each module can be determined. If the voltage parameter V is set as an input parameter and the current I is set as an output parameter, then for each determined voltage V, a uniquely determined current I can be calculated. Scan the voltage parameter V within the effective range to obtain a series of V-I relationships. Store data and draw graphs, which are the output characteristic curves of various energy harvesters.

In the second stage of the simulation system operation, the calculation results of the above modules will be cleared, and the input parameter voltage V is changed to be provided by the energy management simulation module. At this time, the module only outputs the only current I for the overall calculation of the simulation system.

The energy storage simulation module of the multi-energy compound power supply energy simulation system is realized by the lithium-ion battery PNGV model, which calculates the remaining power and battery voltage by integrating the current flowing into and out of the battery, and realizes iterative operation in the discrete-time model. Therefore, the input of the module is the current I, and the output is the voltage V and the battery power SoC. This model building method belongs to the prior art.

The output of the load simulation module is the load demand voltage and demand current. The two parameters are defined by the user to deal with different load demands. And the above two parameters are functions of time, which are used to simulate the change of load with time in transient simulation.

The energy management simulation module connects the various modules and provides input parameters for the above-mentioned energy harvesting simulation module and energy storage simulation module. This block is enabled during the overall simulation in the second phase of the model run.

At each transient time point, the module executes according to the following management strategy:

Step 1) Obtain the voltage and current parameters of the load demand from the load simulation module;

Step 2) Obtain the current energy storage module voltage and electric quantity from the energy storage simulation module;

Step 3) According to the result of the last time point, specify the voltage parameter V of the working state for the energy harvesting simulation module or set the initial value for the voltage parameter (executed at time 0);

Step 4) Read the current output of each sub-module of the energy harvesting simulation module, and select whether to cut off the current output of a certain sub-module according to the output current of the energy harvesting simulation module. This operation is used to cut off the energy harvesting simulation module whose output energy is too low to prevent the error of current reversal, and is used to correspond to the opening/cutting operation of the electronic switch in the actual composite energy system. The truncated energy harvesting simulation sub-module current is not included in subsequent calculations;

Step 5) Calculate the port current of the energy storage simulation module according to the output power of the energy harvesting simulation module and the current and voltage requirements of the load simulation module. The calculation starts from satisfying the current and voltage of the load simulation module, and calculates the input/output current of the energy storage simulation module based on the principle of power balance and considering the limitations of power loss and actual system implementation.

Step 6) Judging the current working state of the simulation system and outputting it. The working status of the simulation system includes: the voltage parameters of the current working status of each energy harvesting simulation sub-module; the system’s on/off operating status for each sub-module; the remaining power of the energy storage simulation module; and the system valid flag (PGOOD). The effective sign of the system is judged by the current of the energy storage simulation module and the remaining power/voltage of the energy storage simulation module. If the demand current of the energy storage simulation module is greater than the allowable value or the remaining power/voltage is insufficient, it means that the energy collected by the system cannot meet the load demand and store The battery is exhausted, and the system is judged to be invalid at this time.

Step 7) Updating the operating voltage parameters for the energy harvesting simulation module model according to the set energy management strategy algorithm. The algorithm is specified by the user. Specifically, algorithms such as proportional method and maximum power tracking (MPPT) can be used. The calculated voltage parameters are assigned to the energy harvesting module in the calculation at the next moment. In order to reduce the amount of calculation and power consumption of the energy management system, the proportional method can be used as the management algorithm of the energy harvesting module, that is, based on the power input of the energy harvesting module, its output power is controlled in equal proportions to achieve approximate energy optimization management.

The above steps 1-7) are executed cyclically at each moment, wherein the voltage parameter V of the energy harvesting simulation module is iteratively calculated at each moment to form a transient simulation.

In addition, the energy harvesting simulation module also includes an energy management strategy module, which is used to store and execute the energy management strategy specified by the user; the energy management strategy module is realized by a state machine model, wherein the implemented energy management strategy can be written in C language . The energy management strategy needs to meet the above steps 1-7;

Further, in step 4), the energy management strategy module can clearly judge the start/stop operation of the energy collection sub-module;

Calculate the energy storage module input/output current in step 5);

Clearly judge and output the working state of the system in step 6);

In step 7), the voltage parameter V required by each sub-module of the energy harvesting simulation module at the next moment is calculated.

Wherein, judging the current working state of the system in the step 6) includes: judging whether the energy harvesting simulation sub-module has an effective output based on the system power balance criterion, estimating the remaining power parameters of the energy storage simulation module based on methods such as the state of charge estimation algorithm, and based on each Simulate the sub-module power curve to judge whether the energy system can meet the load demand.

In one embodiment, the present invention discloses an energy management strategy that functions as an uninterruptible backup power supply (UPS) as follows:

In step 3), the voltage parameters of each energy harvesting simulation sub-module are set to the same value for calculation;

In step 4), when the input current of a certain submodule is less than 0, the submodule is cut off;

In step 5), the power of the energy harvesting simulation module is multiplied by a certain efficiency loss, and compared with the power demanded by the load, the insufficient part of collected energy is supplemented by the energy storage simulation module, and the calculation of the current of the energy storage simulation module is completed; if The collected energy is greater than the power demanded by the load. Considering the actual structure of the system, the excess energy is not charged into the energy storage simulation module, that is, the current of the energy storage simulation module is 0.

In step 6), it is judged that if the voltage of the energy storage simulation module is lower than the set value and is still in the discharge state, it is judged that the system is invalid.

In step 7), according to the proportional relationship between voltage and current before and after the buck circuit, calculate the voltage parameters of the energy harvesting simulation module at the next time according to the current collection current, and limit its maximum/minimum value.

The invention realizes the output characteristic curve simulation of each energy harvester simulation sub-module for evaluating its energy output capability. It can be used as a reference in the design of the composite energy system to optimize the performance of each energy harvester; in addition, it can realize the transient simulation of the overall working state of the system. stability and loading capacity. Furthermore, realizing the optimization of the management strategy and the performance coordination of each device in the composite energy system can improve the development efficiency of the composite energy system.

While particular embodiments of embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that, based on the teachings herein, other modifications can be made without departing from the exemplary embodiments of embodiments of the present invention and its broader aspects. changes and modifications. Therefore, the appended claims are intended to embrace within their scope all such changes and modifications that do not depart from the true spirit and scope of the exemplary embodiments of this invention.

Claims (10)

1. A composite energy simulation system, said system comprising: The energy harvesting simulation module is used to describe and simulate the relationship between the external energy input and electric energy output of the energy harvesting module in the composite energy system; The energy management simulation module is used to describe the basic logical relationship of the energy management algorithm strategy in the composite energy system and simulate it; The energy storage simulation module is used to describe and simulate the power input and output relationship of the energy storage module in the hybrid energy system; The load simulation module is used to describe the power demand of the external power load in the working process of the composite energy system, so as to generate the external input required for the simulation of the composite energy system. 2. The composite energy simulation system according to claim 1, wherein the energy collection simulation module comprises: The solar cell simulation sub-module is used to describe the relationship between the illumination conditions of the solar cell and its output power curve in the energy harvesting simulation module, and to simulate it; The vibration energy harvester simulation sub-module is used to describe the relationship between the external environment vibration conditions of the vibration energy harvester and its output power curve in the energy harvesting simulation module, and to simulate it; The fuel cell simulation sub-module is used to describe the relationship between the fuel supply of the fuel cell in the energy harvesting simulation module and its output power curve, and simulate it; The solar cell simulation sub-module, the vibration energy harvester simulation sub-module, and the fuel cell simulation sub-module are all equivalent circuit building models, and the generated current is calculated according to a certain working voltage. 3. The composite energy simulation system according to claim 2, wherein the energy storage simulation module is established according to the PNGV model of the lithium-ion battery, and calculates the remaining power and energy storage simulation according to the current flowing in/out of the port during the whole time Module voltage value. 4. The composite energy simulation system according to claim 3, wherein the energy management simulation module can provide working voltage parameters for the energy harvesting simulation module, and calculate the port current of the energy storage simulation module according to the set energy management strategy , output the running state of the simulation system. 5. The composite energy simulation system according to claim 4, characterized in that: the load simulation model provides the energy management simulation module model with the voltage and current parameters required by the load. 6. A management strategy applied to the composite energy simulation system as claimed in claims 1-5, comprising the following steps: Step 1) Obtain the voltage and current parameters required by the load from the load simulation module; Step 2) Obtain the current energy storage simulation module voltage from the energy storage simulation module; Step 3) provide the initial value of the working voltage parameter for the energy harvesting simulation module; Step 4) Select whether to cut off the current output of a certain sub-module according to the output current of the energy harvesting simulation module; Step 5) Calculate the port current of the energy storage simulation module according to the output power of the energy harvesting simulation module and the current and voltage requirements of the load simulation module; Step 6) judging the current working state of the system and outputting it; Step 7) Update the operating voltage parameters for the energy harvesting simulation module. 7. The management strategy according to claim 6, wherein the current parameter is set to be positive for inflow and negative for outflow. 8. The management strategy according to claim 6, characterized in that: the calculation in step 5) adopts the principle of power balance. 9. The management strategy according to claim 6, characterized in that: Steps 1-7 are performed iteratively at each time point, so as to realize transient simulation. 10. The management strategy according to claim 6, characterized in that: judging the current working state of the system in said step 6) includes: judging whether the energy harvesting simulation sub-module has an effective output based on the system power balance criterion, based on the state of charge estimation algorithm Estimate the remaining power parameters of the energy storage simulation module, and judge whether the energy system can meet the load demand based on the power curve of each simulation sub-module.