Electrochemical auxiliary device for frequency modulation of electrode boiler

Abstract

The utility model provides an electrochemical auxiliary device for frequency modulation of an electrode boiler, which belongs to the technical field of electric power system control and comprises the electrode boiler and an electrochemical frequency modulation energy storage system. The generator is connected with the electrochemical frequency modulation energy storage system through the station transformer, the electrochemical frequency modulation energy storage system comprises a control system, a PCS and a battery module, and the battery module comprises a plurality of batteries and a battery management unit (BMU). The battery management unit (BMU) comprises a power supply module, a monomer acquisition module, a temperature sampling module, a channel switching module, a balance control module, a communication module, a CPU and a peripheral circuit thereof, a battery system is used for adjusting frequency modulation with fast mileage, an electrode boiler is used for adjusting large load and slow change, and the cost is lower and the effect is better when the battery system and the electrode boiler are combined for frequency modulation.

Description

Technical Field

[0001] The utility model belongs to the technical field of power system control, in particular to an electrochemical auxiliary device for frequency modulation of electrode boilers. Background Art

[0002] Primary frequency regulation refers to the automatic control process in which the control system of the units in the power grid automatically controls the increase or decrease of the active power of the units, limits the change of the power grid frequency, and maintains a stable power grid frequency once the power grid frequency deviates from the rated value.

[0003] The power grid is a huge inertial system. According to the rotor motion equation, when the active power of the power grid is insufficient, the generator rotor accelerates and the power grid frequency increases, otherwise the power grid frequency decreases. Therefore, the primary frequency regulation function is one of the means to dynamically ensure the active power balance of the power grid. When the power grid frequency increases, the primary frequency regulation function requires the unit to reduce the grid-connected active power, otherwise, the unit increases the grid-connected active power. The main parameters of the power grid primary frequency regulation are thermal power units and hydropower units. Some wind power, photovoltaic, and energy storage also have the power grid primary frequency regulation capability. The primary frequency regulation is a feedback closed-loop control that adopts a local response method.

[0004] The high proportion of new energy access has brought great challenges to the safe and stable operation of the power grid. At present, conventional power sources are the main power source for power grid frequency regulation, and the quality of regulation is directly related to the safe and stable operation of the power grid. In the case that new energy sources do not have the ability to regulate the frequency at the first time, the risk of low-frequency oscillation in the power grid has increased. In order to adapt to the new power environment, thermal power units can only improve the response speed and control accuracy of the unit's primary frequency regulation to stabilize the power grid, and their role is crucial.

[0005] At the power production and operation level, the power grid uses large coal-fired power units as the main frequency regulation resource, and the primary frequency regulation performance auxiliary effect of energy storage is far better than that of thermal power units. The introduction of a relatively small number of energy storage systems will be able to quickly and effectively solve the problem of insufficient frequency regulation resources in the regional power grid. Utility Model Content

[0006] In order to effectively solve the problem of insufficient frequency regulation resources in regional power grids, the utility model provides an electrochemical auxiliary device for electrode boiler frequency regulation, which uses a battery system to adjust the frequency regulation with fast mileage and small range, and the electrode boiler performs large load and slow change regulation, with simple structure and low cost.

[0007] The utility model adopts the following technical solutions to solve the above problems:

[0008] An electrochemical auxiliary device for frequency modulation of an electrode boiler, wherein the generator is connected to a power grid via a step-up transformer, and comprises an electrode boiler and an electrochemical frequency modulation energy storage system. The generator is connected to the electrode boiler via a transformer, and the generator is also connected to the electrochemical frequency modulation energy storage system via a plant transformer. The electrochemical frequency modulation energy storage system comprises a control system, a PCS and a battery module. The battery module comprises a plurality of batteries and a battery management unit BMU. The battery management unit BMU comprises a power module, a single cell acquisition module, a temperature sampling module, a channel switching module, a balancing control module, a communication module, a CPU and its peripheral circuits.

[0009] Furthermore, the electrode boiler is connected to a storage tank, and the storage tank is connected to a user.

[0010] Furthermore, the electrode boiler is an electrode hot water boiler, the storage tank is a normal pressure hot water heat storage tank, and the user is a heat user.

[0011] Furthermore, the electrode boiler is an electrode steam boiler, the storage tank is a high-pressure steam storage tank, and the user is a steam user.

[0012] Furthermore, the control system and the battery module are installed in a battery compartment, and the battery module includes a plurality of 280Ah / 3.2V lithium iron phosphate batteries.

[0013] Furthermore, the battery compartment includes multiple battery cabinets and heat dissipation devices.

[0014] Furthermore, the battery management unit is placed in a control system, which includes a slave battery management unit (BCU), a master battery management unit (BAU), a high-voltage line control unit, an energy storage cabinet pre-charging circuit, a high-voltage detection unit, a thermal management unit, a current detection unit, an emergency stop system, and a battery monitoring system (PC), and the energy storage cabinet pre-charging circuit is a parallel circuit.

[0015] Furthermore, the generator adopts two generators, and the voltage is transmitted to the power grid through the step-up transformer respectively.

[0016] The beneficial effects of the utility model are:

[0017] 1. The utility model uses a battery system to adjust the frequency of fast mileage and small mileage. Since the electrode boiler has a slow adjustment speed but a large adjustment power range, it is used to adjust the large load with slow changes. The combination of the two is because if a battery system with a particularly large capacity is used for frequency adjustment, the utilization rate is low and the cost is high; if a battery system with a small capacity is used for frequency adjustment, the battery is always used deeply and the life is reduced. Therefore, it is a more economical way to use a medium-capacity small battery system in combination with an electrode boiler plus a storage tank for frequency adjustment;

[0018] 2. Unlike traditional synchronous generator sets, the energy storage system uses a high-frequency inverter device to connect to the grid, and its grid-connected characteristics are manifested as a controlled current source rather than a voltage source. When a single-phase or three-phase short-circuit fault occurs at the generator end, the maximum short-circuit current that the grid-connected inverter of the energy storage system can provide is constrained by the maximum current that the inverter power device can withstand, and does not exceed 1.5 times the rated current of the grid-connected inverter device;

[0019] 3. After the energy storage system is connected, the short-circuit current under the high-voltage power transformer is minimally affected, and is far lower than the shutdown capacity of the circuit breaker in the high-voltage power section, so there is no need to replace the original circuit breaker;

[0020] 4. The grid-connected inverter device of the energy storage system is equipped with a complete voltage and current protection device. When a voltage drop or short-circuit fault occurs in the system, or an overcurrent fault occurs in the grid-connected inverter, the electrochemical frequency modulation energy storage system will be quickly removed from the grid connection point, thereby further reducing the impact of the short-circuit fault current on the machine end after the energy storage system is connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present utility model, the drawings required for use in the description of the specific implementation methods will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a schematic diagram of Embodiment 1 of the present utility model;

[0023] Figure 2 This is a schematic diagram of the structure of the battery compartment of the utility model;

[0024] Figure 3 This is a schematic diagram of Example 2 of the utility model.

[0025] In the figure, 1-generator; 2-transformer; 3-electrode boiler; 4-step-up transformer; 5-grid; 6-plant transformer; 7-electrochemical energy storage system; 701-control system; 702-battery module; 703-battery compartment; 704-battery cabinet; 705-heat dissipation device; 8-storage tank; 9-user. DETAILED DESCRIPTION

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Example 1

[0027] like Figure 1 , Figure 2 As shown, the utility model provides an electrochemical auxiliary device for frequency modulation of electrode boilers. The generator 1 is connected to the power grid 5 through a step-up transformer 4, including an electrode boiler 3 and an electrochemical frequency modulation energy storage system 7. The generator 1 is connected to the electrode boiler 3 through a transformer 2. The step-up transformer 4 steps up the electricity generated by the generator 1 to 220 kV or higher voltage and transmits it to the power grid 4. The electrode boiler 3 is connected to a storage tank 8, and the storage tank 8 is connected to a user 9. When the electrode boiler 3 adopts an electrode hot water boiler, the storage tank 8 is a normal pressure hot water heat storage tank, and the user 9 is a heat user. The transformer 2 converts the electricity generated by the generator 1 into The electrode hot water boiler is 6-20kV, which converts electricity into hot water. After receiving the DCS instruction of the power plant, the electrode hot water boiler starts to run. The heat generated by the electrode hot water boiler can be stored in the storage tank 8, that is, the heat storage tank. The normal pressure hot water heat storage tank stores the excess heat generated by the electrode hot water boiler, releases the heat when there is a heat demand, and can also be directly shared with heat users; when the electrode boiler 3 adopts the electrode steam boiler, the storage tank 8 is a high-pressure steam storage tank, and the user 9 is a steam user, both of which use electricity that requires large load regulation to drive the electric boiler for high-power regulation.

[0028] The generator 1 is connected to the electrochemical frequency modulation energy storage system 7 through the plant transformer 6. The plant transformer 6 reduces the voltage of the electricity generated by the generator 1 to 6.3kV and connects it to the electrochemical frequency modulation energy storage system 7. The electrochemical frequency modulation energy storage system 7 includes a control system 701, a PCS and a battery module 702. The battery module 702 includes multiple batteries and a battery management unit (BMU). In this embodiment, the battery module 702 includes 16 280Ah / 3.2V lithium iron phosphate batteries, which are assembled in a 1-in-16 series combination. The battery management unit (BMU) is the smallest module unit of the battery management system. The battery management unit (BMU) includes a power module, a single cell acquisition module, a temperature sampling module, a channel switching module, a balancing control module, a communication module, a CPU and its peripheral circuits, and measures the single cell voltage, the total voltage of the battery string, the external working power supply voltage, the battery ambient temperature, the balancing voltage (over-voltage protection), and the balancing current (charging / discharging) in real time, and can actively report the real-time monitoring data to the battery cluster management unit BCMS through the CAN2.0 communication bus and accept the BCMS control instructions. Unlike traditional synchronous generator sets, the electrochemical frequency-regulated energy storage system 7 uses a high-frequency inverter device to connect to the grid, and its grid-connected characteristics are manifested as a controlled current source rather than a voltage source. When a single-phase or three-phase short-circuit fault occurs at the machine end, the maximum short-circuit current that the grid-connected inverter of the energy storage system can provide is constrained by the maximum current that the inverter power device can withstand, and does not exceed 1.5 times the rated current of the grid-connected inverter device. That is, in the worst case, the effects of the grid-connected inverter device of the energy storage system and the protection units at all levels of the access circuit are completely ignored. After the energy storage system is connected, the maximum impact on the short-circuit current of each branch on the low-voltage side of the high-voltage transformer (taking a 6MW battery as an example) does not exceed:

[0029]

[0030] After the electrochemical frequency modulation energy storage system 7 is connected, the short-circuit current under the high-voltage power plant transformer is very small, and is far lower than the shutdown capacity of the circuit breaker in the high-voltage power plant section, so there is no need to replace the original circuit breaker. In fact, the grid-connected inverter of the electrochemical frequency modulation energy storage system 7 is equipped with a complete voltage and current protection device. When the system has a voltage drop or short-circuit fault, or the grid-connected inverter has an overcurrent fault, the electrochemical frequency modulation energy storage system 7 will be quickly removed from the grid connection point, thereby further reducing the impact of the short-circuit fault current on the machine end after the energy storage system is connected.

[0031] The control system 701 and the battery module 702 are installed in the battery compartment 703, and the battery compartment 703 includes multiple battery cabinets 704 and a heat dissipation device 705. In this embodiment, the heat dissipation device 705 adopts an air conditioner, and the battery module 702 is integrated in the battery cabinet 704. The battery management unit BMU is placed in the control system 701. The control system 701 also includes a slave battery management unit (BCU), a master battery management unit (BAU), a high-voltage line control unit, a pre-charging parallel line of the energy storage cabinet, a high-voltage detection unit, a thermal management unit, a current detection unit, an emergency stop system, and a battery monitoring system PC, which are used to monitor and manage the energy storage system, wherein the battery management unit (BMU) is mainly used to detect the single cell voltage and temperature of the battery in the battery module, alarm for abnormal voltage and temperature status of the single cell, and send relevant voltage information, temperature information and alarm information to the slave battery management unit (BCU); BCU (Slave Battery Management The Master Battery Management Unit (BAU) is responsible for the overall management of the operation of the entire power cabinet, and is responsible for single cell voltage monitoring and temperature monitoring; total voltage and total current collection of the power cabinet; diagnosis of functional status such as input power supply and relay status; intelligent operation of the power cabinet system and real-time monitoring; The BAU (Master Battery Management Unit) module is an important battery management unit in the BMS, responsible for information collection of the entire battery system, SOC calculation and information exchange with each unit module to ensure system safety.

[0032] Electrode boiler 3 generally adjusts power at a speed of 0.5-2MW per second, which does not meet the requirements of frequency modulation. Pure lithium battery frequency modulation has low efficiency (compared to electric boilers) and low power (large-scale lithium battery energy storage requires high investment and low safety). If electric boilers and lithium battery frequency modulation are combined, the shortcomings of lithium battery frequency modulation can be made up.

[0033] The utility model uses a battery system to adjust the frequency of fast mileage and small mileage, and because the electrode boiler 3 is slow to adjust, it is adjusted for large loads and slow changes. The combination of the two is because if a battery system with a particularly large capacity is used for frequency adjustment, the utilization rate is low and the cost is high; if a battery system with a small capacity is used for frequency adjustment, the battery is always used deeply and the life is reduced. Therefore, it is a more economical way to use a medium-capacity small battery system in combination with an electrode boiler 3 and a storage tank 8 to adjust the frequency.

[0034] If the total frequency modulation mileage of the power grid is about 200MW each time, when it is broken down into each generator set, the frequency modulation mileage of the generator set is generally in the range of 2-6MW; the capacity of the equipment installed for AGC frequency modulation in the power grid is mostly 9MW / 9MWh, consisting of 3 sets of containerized battery frequency modulation equipment. If the battery energy storage capacity is 9MWh, in order to extend the battery life, the frequency modulation mileage is controlled between 2MW and 8MW, so the available capacity of the battery is: 6MWh (360MW•min).

[0035] The current frequency modulation frequency of the power grid can be considered as once per minute, that is, the frequency can be adjusted 60 times in 1 hour. When the average frequency modulation mileage is calculated as 4MW each time, the total discharge amount in 1 hour during the continuous discharge frequency modulation process is:

[0036]

[0037] That is, when the battery is charged from the minimum discharge capacity (2MWh) to the designed full charge capacity (8MW), the number of charging frequency modulations that can be achieved is:

[0038]

[0039] Similarly, if the battery is fully charged, 90 consecutive discharge frequency modulation times can be achieved.

[0040] The mileage of a single frequency regulation command of the power grid is generally around 3MW, and sometimes it can reach 6MW.

[0041] To extend the battery life, the maximum charge capacity of the battery is limited to 8MW (89%) and the minimum discharge power is limited to 2MW (22%). This also ensures that the battery frequency regulation system can meet the needs of 6MW frequency regulation mileage in a small amount of time.

[0042] When the frequency regulation compensation value is high, the electrode boiler 3 and the storage tank 8 participate in the frequency regulation work, which can effectively increase the profit.

[0043] The electrode boiler 3 and the storage tank 8 can greatly increase the mileage of a single frequency modulation, and can also greatly reduce the number of cumulative deep charge and discharge times of the battery, thereby greatly extending the service life of the battery.

[0044] Since the frequency modulation speed and response time parameters of the electrode boiler 3 and the storage tank 8 are lower than the corresponding parameters of the battery, the method of coordination between the two is:

[0045] (1) The battery responds to the frequency modulation command first, responding to the frequency modulation command requirements with the shortest response time, highest rate, and highest regulation accuracy;

[0046] (2) The electrode boiler 3 and the storage tank 8 shall be regulated to the best of their ability in accordance with the instructions;

[0047] (3) The battery adjusts the power by increasing or decreasing the power in the opposite direction by an equal amount according to the power change of the electrode boiler 3.

[0048] The electrode boiler 3 and the storage tank 8 maintain a certain adjustment margin to assist the frequency regulation system in increasing the frequency regulation mileage; the electrode boiler 3 and the storage tank 8 accept the dispatch of the "power plant function" of the power grid and also participate in a certain frequency regulation.

[0049] The utility model is equipped with only one set of battery energy storage frequency modulation equipment, and its power supply line is connected to the output end of the factory power transformer after passing through two power isolation switches. Gateway meters are installed in both power supply lines so that the network source frequency coordination device can collect the operating power of the battery frequency modulation equipment respectively.

[0050] The two power switches work in an interlocking manner to ensure that only one power source is connected.

[0051] The battery frequency regulation equipment can select the service object according to the different frequency regulation income of the two generator sets or other factors (such as maintenance).

[0052] The electrode boiler 3 and the storage tank 8 are an independent set of equipment, and their control systems exchange information with the frequency modulation control system and also exchange information with the power grid dispatching system. Example 2

[0053] like Figure 3 As shown, the generator 1 adopts two generators, which transmit voltage to the power grid 5 through the step-up transformer 4 respectively. Other technical features are the same as those of Example 1.

[0054] The device can be applied to different generators and has wide applicability.

[0055] The above embodiments describe the present invention in detail, but the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of application of the present invention shall still fall within the scope of the patent coverage of the present invention.

Claims

1. An electrochemical auxiliary device for frequency modulation of an electrode boiler, wherein a generator (1) is connected to a power grid (5) via a step-up transformer (4), characterized in that: The invention comprises an electrode boiler (3) and an electrochemical frequency modulation energy storage system (7), wherein the generator (1) is connected to the electrode boiler (3) via a transformer (2), and the generator (1) is connected to the electrochemical frequency modulation energy storage system (7) via a plant transformer (6). The electrochemical frequency modulation energy storage system (7) comprises a control system (701), a PCS and a battery module (702), wherein the battery module (702) comprises a plurality of batteries and a battery management unit (BMU), and wherein the battery management unit (BMU) comprises a power module, a single cell acquisition module, a temperature sampling module, a channel switching module, a balancing control module, a communication module, a CPU and its peripheral circuits.

2. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 1, characterized in that: The electrode boiler (3) is connected to a storage tank (8), and the storage tank (8) is connected to a user (9).

3. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 2, characterized in that: The electrode boiler (3) is an electrode hot water boiler, the storage tank (8) is a normal pressure hot water heat storage tank, and the user (9) is a heat user.

4. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 2, characterized in that: The electrode boiler (3) is an electrode steam boiler, the storage tank (8) is a high-pressure steam storage tank, and the user (9) is a steam user.

5. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 1, characterized in that: The control system (701) and the battery module (702) are installed in a battery compartment (703), and the battery module (702) includes a plurality of 280Ah / 3.2V lithium iron phosphate batteries.

6. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 5, characterized in that: The battery compartment (703) includes a plurality of battery cabinets (704) and a heat dissipation device (705).

7. The electrochemical auxiliary device for frequency modulation of an electrode boiler according to claim 6, characterized in that: The battery management unit is placed in a control system (701), and the control system (701) includes a slave battery management unit (BCU), a master battery management unit (BAU), a high-voltage line control unit, an energy storage cabinet pre-charging line, a high-voltage detection unit, a thermal management unit, a current detection unit, an emergency stop system, and a battery monitoring system (PC), and the energy storage cabinet pre-charging line is a parallel circuit.

8. An electrochemical auxiliary device for frequency modulation of an electrode boiler according to any one of claims 1 to 7, characterized in that: The generator (1) uses two generators, each of which transmits voltage to the power grid (5) through the step-up transformer (4).

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