CN106803680A - Energy management method and system for echelon battery pack energy storage power station - Google Patents

Abstract

The invention provides an energy management system of a echelon battery pack energy storage power station, which adopts a distributed topological structure and comprises a echelon battery module, an energy storage converter and a monitoring system, wherein a monitoring period is set in the monitoring system, and the following steps are executed when each monitoring period begins: step 1, acquiring the charge state of each echelon battery module through a charge state acquisition unit arranged in each branch echelon battery module, and uploading the charge state to a monitoring system through a CAN (controller area network) bus; and 2, calculating a power value of each branch circuit which needs to be controlled in real time by the monitoring system according to the charge state of each branch circuit echelon battery module and the set dynamic power value, and sending the power value to the corresponding energy storage converter for control, thereby controlling the charging/discharging real-time power of each branch circuit. The invention ensures that the total power meets the system requirement, simultaneously improves the operation efficiency and the service life of the system, and avoids the risk of single branch failure caused by single branch overcharge or overdischarge.

Description

Energy management method and system for cascaded battery pack energy storage power station

technical field

The invention relates to the field of energy storage and charging, and specifically provides an energy management method and system for cascade battery pack energy storage power stations.

Background technique

At present, the electric vehicle industry and industry are developing very rapidly. With the promotion and application of electric vehicles, there are a huge number of decommissioned cascade batteries. The remaining capacity of cascade batteries is usually more than 80%, and there is a large space for utilization. How to find a suitable step-by-step utilization scenario to reuse such a huge amount of power batteries has become a serious problem facing the electric vehicle industry. The construction of energy storage power stations in the energy storage industry requires a large number of low-cost energy storage batteries. If the low-cost cascade batteries retired from electric vehicles can be effectively used in the energy storage field, it will greatly promote the development of the energy storage industry.

Based on the differences in the application of batteries in electric vehicles, there are large differences in the state of charge of different echelon batteries, and there are many technical problems in the application of energy storage. How to avoid the difference in battery state of charge and adopt appropriate methods to realize echelon The large-scale and effective use of batteries in the field of energy storage has become an urgent technical problem to be solved in the electric vehicle and energy storage industries.

The existing design method adopts single branch or multi-branch overall control, and the control target only considers the system power demand, without considering the state of charge of the branch or the refined energy management of the state of charge of the multi-branch. Ensure the overall operating efficiency and life of the system are maximized.

The problems to be solved by the present invention are as follows: 1) How to realize the comprehensive energy management of cascade battery energy storage power stations with large differences in state of charge; 2) How to improve the operating efficiency of cascade battery energy storage power stations with large differences in state of charge and longevity.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the present invention provides an energy management method and system for cascaded battery pack energy storage power stations, which adopt distributed state-of-charge collection, centralized intelligent calculation and dynamic power distribution management methods to meet the requirements of Under the premise of system charging and discharging power requirements, the dynamic distribution of branch power of echelon batteries with different states of charge can realize the energy management of energy storage power stations based on different states of charge of echelon batteries, and at the same time improve the existence of state of charge. The operating efficiency and lifespan of cascade battery energy storage power station systems with large differences.

An energy management method for a cascaded battery pack energy storage power station proposed by the present invention sets a monitoring cycle and executes the following steps at the beginning of each monitoring cycle:

Step 1. Collect the state of charge of the echelon battery modules of each branch of the energy storage power station by using the method of distributed state of charge collection, and set the total dynamic power value of each branch;

Step 2: Calculate the real-time power value to be controlled for each branch according to the state of charge and dynamic power value of the echelon battery modules of each branch, and control the real-time power of charging/discharging for each branch according to the power value.

Preferably, the calculation method for the real-time control power value of each branch is:

Use i to represent the branch circuit number of the cascade battery module, where i=1,2,...,n; n is the total number of branches of the cascade battery module;

Step 21, calculate the current available capacity E _i of each branch cascade battery module, the formula is

E _i =SOC _i *EN

Where SOC _i is the state of charge of the i-th branch cascade battery module, EN the original nominal energy of each branch cascade battery module;

Step 22, calculate the charging/discharging time t ₀ i of each branch cascade battery module, the formula is

t ₀ i = E _i /PK

Where PK is the standard charge/discharge rate;

Step 23, calculate the average tav ₀ of the charging/discharging time of each branch cascade battery module, the formula is

tav ₀ ＝(t ₀ 1+t ₀ 2+…+t ₀ n)/n

Step 24, calculate the corresponding power value P ₀ i when the charging/discharging time of each branch cascade battery module is controlled at the value of tav ₀ , the formula is

P ₀ i =E _i /tav ₀

Step 25, calculate the ratio kp of the power value P 0 i corresponding to the sum of the power values P ₀ i of each branch echelon battery module and the required power P when the charging/discharging time is controlled at the tav ₀ value, the formula is

kp＝(P ₀ 1+P ₀ 2+...+P ₀ n)/P

Step 26, calculate the real-time power Pi that actually needs to be charged/discharged by each branch cascade battery module, the formula is

Pi=P ₀ i/kp.

The present invention also provides an energy management system for a cascade battery pack energy storage power station, the system adopts a distributed topology and includes a cascade battery module, an energy storage converter, and a monitoring system;

A state-of-charge acquisition unit is arranged inside each branch-echelon battery module, which is used to collect the state-of-charge of each branch-echelon battery module at the beginning of each monitoring cycle;

The monitoring system is used to calculate the real-time control power value of each branch according to the state of charge of each branch cascade battery module collected in each monitoring cycle; according to the state of charge and dynamic power value of each branch cascade battery module , and control the real-time power of charging/discharging of each branch according to the power value;

The energy storage converter is used to control the real-time power of charging/discharging of each branch cascade battery module in each monitoring cycle according to the calculated real-time control power value of each branch.

Preferably, the method for calculating the real-time control power value of each branch is the above-mentioned method for calculating the real-time control power value of each branch.

Preferably, the battery module, the energy storage converter, and the monitoring system are respectively connected by a high-speed CAN bus.

Preferably, the energy storage converter is a bidirectional energy storage converter.

The present invention periodically adopts the management method of distributed state of charge collection, centralized intelligent calculation and dynamic power distribution to ensure that the total power meets the system requirements. At the same time, the power setting value of each branch is related to the state of charge of the branch. The charging and discharging time of the branches is basically the same, and the state of charge of each branch can be gradually adjusted to approach the average value, which improves the operating efficiency and life of the system, and avoids the risk of single branch failure caused by overcharging or overdischarging of a single branch.

Description of drawings

Figure 1 is a block diagram of the modular design system topology of an energy storage power station based on cascaded batteries;

Fig. 2 is a flowchart of a method for calculating the real-time control power value of each branch.

detailed description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

Considering the circuit topology of the modular multi-branch circuit of the echelon battery of the energy storage power station, the present invention adopts the management method of distributed state of charge collection, centralized intelligent calculation and dynamic power distribution, under the precondition of meeting the demand of system charging and discharging power, The branch power of each branch echelon battery module with different states of charge is dynamically allocated, which can realize the energy management of the energy storage power station based on the different states of charge of each branch echelon battery module, and at the same time improve the state of charge. The operating efficiency and lifespan of different cascade battery energy storage power station systems.

As shown in Fig. 1, an energy management system of a cascade battery pack energy storage power station in this embodiment includes a battery module, an energy storage converter, and a monitoring system;

The battery module of each branch is used as a cascade battery module, and a charge state acquisition unit is arranged inside each branch cascade battery module, which is used to collect the charge state of each branch cascade battery module at the beginning of each monitoring cycle; The state-of-charge acquisition unit inside each branch-echelon battery module uploads the collected state-of-charge and related control and protection information of each branch-echelon battery module to the monitoring system through the CAN-A bus;

The monitoring system is used to calculate the real-time control power value of each branch according to the state of charge of each branch cascade battery module collected in each monitoring cycle; according to the state of charge and dynamic power value of each branch cascade battery module , and control the real-time power of charging/discharging of each branch according to the power value; in this embodiment, the calculation of the real-time controlled power value of each branch is calculated using an energy management algorithm;

The energy storage converter receives the real-time control power value of each branch issued by the monitoring system through the CAN-B bus, and controls the charging/discharging of the echelon battery modules of each branch in each monitoring cycle through the CAN-C bus real-time power.

The energy storage converter in this embodiment is a bidirectional energy storage converter;

Based on the above-mentioned energy management system, this embodiment also provides an energy management method for cascaded battery pack energy storage power stations. The monitoring cycle is set in the monitoring system, and the following steps are performed at the beginning of each monitoring cycle:

Step 1: Use the distributed state of charge acquisition method to collect the state of charge of each branch cascade battery module of the energy storage power station through the internal charge state acquisition unit of each branch cascade battery module, and store the The collected state-of-charge information is uploaded to the monitoring system through the CAN-A bus; the total dynamic power value of each branch is set in the monitoring system for subsequent real-time calculation of the power value to be controlled;

Step 2. The monitoring system calculates the real-time controllable power value of each branch based on the state of charge and dynamic power value of the echelon battery modules of each branch, and sends the real-time controllable power value of each branch to the The energy storage converter of each branch is controlled, and the energy storage converter of each branch controls the real-time power of charging/discharging of each branch according to the power value.

In this embodiment, the method for calculating the real-time controlled power value of each branch is specifically an energy management algorithm. In this algorithm, i is used to represent the branch number of the cascaded battery module, where i=1,2,... .,n; n is the total number of branches of the cascade battery module; the specific steps are as follows:

Step 21, calculate the current available capacity E _i of each branch cascade battery module, as shown in formula (1);

E _i =SOC _i *EN (1)

Where SOC _i is the state of charge of the i-th branch cascade battery module, EN the original nominal energy of each branch cascade battery module;

Step 22, calculate the charging/discharging time t ₀ i of each branch cascade battery module, as shown in formula (2);

t ₀ i = E _i /PK (2)

Where PK is the standard charge/discharge rate;

Step 23, calculate the average value tav ₀ of the charging/discharging time of each branch cascade battery module, as shown in formula (3);

tav ₀ =(t ₀ 1+t ₀ 2+...+t ₀ n)/n (3)

Step 24, calculate the corresponding power value P ₀ i when the charging/discharging time of each branch cascade battery module is controlled at tav ₀ , as shown in formula (4);

P ₀ i =E _i /tav ₀ (4)

Step 25, calculate the ratio kp of the sum of the power values P 0 i corresponding to the power values P ₀ i of each branch echelon battery module and the required power P controlled at tav ₀ for charging/discharging time, as shown in formula (5);

kp＝(P ₀ 1+P ₀ 2+...+P ₀ n)/P (5)

Step 26, calculate the real-time power Pi that actually needs to be charged/discharged by each branch echelon battery module, as shown in formula (6);

Pi=P ₀ i/kp (6)

In this embodiment, the charging/discharging time is the definition of charging/discharging time in the conventional sense. For a clearer expression, it is specifically described as: the charging time is the time required for the echelon battery module to continue charging to the upper limit of the charging rating in the current state, and the discharging time is The time is the time required for the cascade battery module to discharge to the lower limit of the discharge rating in the current state; the current state refers to information such as the state of charge of the cascade battery module in the corresponding branch that is collected in each monitoring cycle.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings, but those skilled in the art will easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims (6)

1. An energy management method for cascaded battery pack energy storage power stations, characterized in that the monitoring period is set, and the following steps are performed at the beginning of each monitoring period: Step 1. Collect the state of charge of the echelon battery modules of each branch of the energy storage power station by using the method of distributed state of charge collection, and set the total dynamic power value of each branch; Step 2: Calculate the real-time power value to be controlled for each branch according to the state of charge and dynamic power value of the echelon battery modules of each branch, and control the real-time power of charging/discharging for each branch according to the power value. 2. The energy management method according to claim 1, characterized in that the calculation method of the real-time control power value of each branch is as follows: Use i to represent the branch circuit number of the cascade battery module, where i=1,2,...,n; n is the total number of branches of the cascade battery module; Step 21, calculate the current available capacity E _i of each branch cascade battery module, the formula is E _i =SOC _i *EN Where SOC _i is the state of charge of the i-th branch cascade battery module, EN the original nominal energy of each branch cascade battery module; Step 22, calculate the charging/discharging time t ₀ i of each branch cascade battery module, the formula is t ₀ i = E _i /PK Where PK is the standard charge/discharge rate; Step 23, calculate the average tav ₀ of the charging/discharging time of each branch cascade battery module, the formula is tav ₀ ＝(t ₀ 1+t ₀ 2+…+t ₀ n)/n Step 24, calculate the corresponding power value P ₀ i when the charging/discharging time of each branch cascade battery module is controlled at the value of tav ₀ , the formula is P ₀ i =E _i /tav ₀ Step 25, calculate the ratio kp of the power value P 0 i corresponding to the sum of the power values P ₀ i of each branch echelon battery module and the required power P when the charging/discharging time is controlled at the tav ₀ value, the formula is kp＝(P ₀ 1+P ₀ 2+...+P ₀ n)/P Step 26, calculate the real-time power Pi that actually needs to be charged/discharged by each branch cascade battery module, the formula is Pi=P ₀ i/kp. 3. An energy management system for a cascade battery pack energy storage power station, the system adopts a distributed topology, including a cascade battery module, an energy storage converter, and a monitoring system, characterized in that, A state-of-charge acquisition unit is arranged inside each branch-echelon battery module, which is used to collect the state-of-charge of each branch-echelon battery module at the beginning of each monitoring cycle; The monitoring system is used to calculate the real-time control power value of each branch according to the state of charge of each branch cascade battery module collected in each monitoring cycle; according to the state of charge and dynamic power value of each branch cascade battery module , and control the real-time power of charging/discharging of each branch according to the power value; The energy storage converter is used to control the real-time power of charging/discharging of each branch cascade battery module in each monitoring cycle according to the calculated real-time control power value of each branch. 4 . The energy management system according to claim 3 , wherein the method for calculating the real-time control power value of each branch is the method according to claim 2 . 5. The energy management system according to claim 3, wherein the battery module, the energy storage converter, and the monitoring system are respectively connected by a high-speed CAN bus. 6. The energy management system according to claim 3, wherein the energy storage converter is a bidirectional energy storage converter.