A Method for High-Toughness Coordinated Operation of Data Center and Distribution Network

Abstract

The present invention discloses a method for highly resilient coordinated operation of a data center and a distribution network. During the load restoration process of the distribution network, the present invention introduces a load with spatio-temporal flexibility, namely a data center, and considers the dispatching strategy of the standby energy storage within the data center. In addition, a distributed generator that can act as a voltage source is introduced. The introduction of these two helps to enhance the resilience of the distribution system, enables the distribution system to quickly restore critical loads, and reduces economic losses during power outages. Against the background that the data center has high requirements for power supply stability, the present invention introduces a flexible substation. As a new type of power electronic converter, the flexible substation is installed on both sides of the data center, enabling the data center to operate on a DC bus. While providing efficient and stable power supply, it can reduce the operating costs of the data center.

Description

Technical Field

[0001] The present invention relates to the technical field of post-disaster restoration of power grids, and specifically to a method for highly resilient coordinated operation of a data center and a distribution network. Background Art

[0002] In recent years, with the intensification of global climate change, large-scale power outages caused by extreme disasters have occurred frequently, resulting in serious economic losses. Compared with the transmission network, the distribution network has a weaker ability to cope with extreme disasters and is more likely to have power outages due to sudden disasters. Moreover, the distribution network is connected to industrial and commercial as well as residential end loads. Therefore, once the distribution network fails, it will have a huge impact on economic and social benefits.

[0003] Among them, the Internet data center, as a key distribution network infrastructure, is different from other loads in the power system. It has special spatio-temporal load transfer characteristics and is an important flexible load in the power system. The data center can improve the resilience of the power system through the spatio-temporal scheduling of workloads and the interaction between the backup energy storage in the data center park and the power system. From the perspective of data center operation, the data center is driven by electricity. Therefore, power outages in the distribution network have always been a huge threat to data center operation. Therefore, considering the heavy dependence on electricity and its key position in the local economy, the data center has become a new key load in the distribution system, and the effective restoration of the distribution system after natural disasters is crucial for reducing the economic losses of the data center. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for highly resilient coordinated operation of a data center and a distribution network to solve the problems raised in the above background art. To improve the resilience of the distribution system, the present invention introduces a data center as a key load of the distribution network and establishes an emergency operation model for the data center park during the restoration stage of the distribution network. Among them, the workload and backup energy storage of the data center jointly assist in restoring the key loads of the distribution network. To ensure the operational stability of the data center, the present invention introduces a flexible substation, which can enable the data center to operate more stably and efficiently on the DC bus, and formulates a voltage support strategy for the restoration of the distribution network based on the flexible substation and distributed generation mechanism. A coordinated power supply restoration method is proposed with the goal of minimizing the losses during the restoration process of the key loads of the distribution network and minimizing the losses of the workload of the data center. Spatio-temporal coordination between the source, network, storage, and demand side can be achieved without violating physical feasibility.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for highly resilient coordinated operation of a data center and a distribution network, comprising the following steps:

[0007] Establish an emergency operation model for the data center park during the distribution network restoration stage. After the distribution network power outage, the insufficient power supply will have a significant impact on the operation of the data center. Therefore, in the technical solution of the present invention, it is first necessary to establish an emergency operation model for the data center. As Figure 1 , the basic structure of the data center park includes the data center itself, backup energy storage, and a flexible substation. During the emergency operation of the data center park, the power demand of the data center can be changed through the spatio-temporal transfer of the data center workload. By reasonably allocating the backup energy storage, power support can be provided for the data center, and it can help the distribution system restore critical loads when power is restored. Therefore, in this part, an emergency data flow scheduling model for the data center and a backup energy storage allocation strategy for the data center park are established. Specifically, a data center load scheduling model based on data flow scheduling and its constraints considering two load regulation methods, namely geographical load balancing and time scheduling of delay-tolerant loads; a three-stage scheduling strategy for backup energy storage in the data center park. In the first stage, the backup energy storage in the park only supplies power to the data center. In the second stage, the distribution network provides power support for charging the data center and the backup energy storage. In the third stage, the backup energy storage responds to the allocation of the distribution system.

[0008] The emergency data flow scheduling model for the data center mainly includes a data center power consumption model and a spatio-temporal scheduling model for the data center workload. The data center power consumption model uses the CPU utilization model and uses the power utilization efficiency to characterize the proportional relationship between the power of IT equipment and the total power of the data center. The power of IT equipment considers the processing power consumption of delay-tolerant workloads and delay-sensitive workloads. The spatio-temporal scheduling model for the data center workload considers the spatial scheduling and workload deletion constraints of delay-sensitive loads, as well as the time scheduling and workload deletion constraints of delay-tolerant loads.

[0009] In addition, through the reasonable planning and allocation of backup energy storage, flexible interaction with the distribution network can be carried out on the premise of meeting the power supply stability of the data center to enhance the resilience of the distribution network. The scheduling strategy of the backup energy storage in this invention is divided into three stages. In the first stage, the backup energy storage in the park only supplies power to the data center. In the second stage, the distribution network provides power support for charging the data center and the backup energy storage. In the third stage, the backup energy storage can respond to the allocation of the distribution system;

[0010] Establish a voltage support strategy based on flexible substations and distributed generators: After the distribution network fault is isolated, consider the voltage support effect that flexible substations and distributed generators can play on the bus. Consider that flexible substations and distributed generators are in two working states, namely the power regulation mode and the voltage support mode. For a flexible substation, when the buses on both sides are in normal operation, the flexible substation operates in the power regulation mode to achieve power interaction between the AC and DC buses; when one side bus is in normal operation, the flexible substation operates in the voltage support mode to provide voltage support for the de-energized bus. For distributed generators, when adjacent nodes are de-energized, they will operate in the voltage support mode to provide voltage support for the de-energized nodes; if all are in normal operation, they are in the power regulation mode, and the flexible substation terminal and distributed generators provide voltage support and assist available substations.

[0011] Consider the post-disaster restoration modeling of the distribution network for the data center: After the emergency operation model of the data center park and the voltage support strategy based on flexible substations and distributed generators are established, the model parameters should be delivered to the distribution network operator for integration, and distribution network power flow constraints and distribution network radial topology constraints should be added to merge into a restoration strategy model for the overall distribution network, which is jointly solved by the distribution network operator to finally achieve the restoration of the critical loads of the distribution network; the objective function and constraint conditions during the distribution network restoration process are to minimize the total power outage losses of the data volume reduction in the data center and other un-restored power loads during the power supply restoration process.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] (1) During the load restoration process of the distribution network, the present invention introduces a load with spatio-temporal flexibility, namely the data center, and considers the mobilization strategy of the standby energy storage in the data center. In addition, a distributed generator that can act as a voltage source is introduced. The introduction of these two helps to enhance the resilience of the distribution system, helps the distribution system quickly restore critical loads, and reduces economic losses during power outages;

[0014] (2) Under the background that the data center has high requirements for power supply stability, the present invention introduces a flexible substation. As a new type of power electronic converter, the flexible substation is installed on both sides of the data center, enabling the data center to operate on the DC bus, which can reduce the operating cost of the data center while providing efficient and stable power supply. Brief Description of the Drawings

[0015] Figure 1 It is the basic structure diagram of the AC-DC hybrid distribution network including the data center park;

[0016] Figure 2Schematic diagram of the coupling mechanism between the data center and the distribution network and the high-resilience coordinated operation method;

[0017] Figure 3 Schematic diagram of the data center workload allocation process. Specific implementation manner

[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to Figures 1 to 3 , in the embodiments of the present invention, a high-resilience coordinated operation method for a data center and a distribution network includes the following steps:

[0020] (1) Emergency operation model of the data center park during the distribution network restoration stage, which is described in detail as follows:

[0021] The emergency operation model of the data center park during the distribution network restoration stage of the present invention is mainly divided into a data center data flow scheduling model and a three-stage planning strategy for standby energy storage.

[0022] In this section, it is assumed that data centers managed by the same data center operator are distributed at different locations of the same distribution network. As Figure 3 shown, the data center operator aggregates the workload requests of network users through the front-end proxy according to the principle of proximity. After aggregation, the front-end proxy spatially allocates the latency-sensitive workloads according to the power availability information of each data center. The latency-tolerant loads are distributed to each data center by the balancer. If it is not worth using the computing resources or exceeds the computing power or latency time requirements of the data center, the data load will be deleted. In this way, the limited power can be utilized to the maximum extent to reduce the losses of the data center operator. In this chapter, all nodes mentioned are data center nodes (i.e., ).

[0023] The technical solution of the present invention assumes that all servers in each data center are homogeneous, that is, the performance, rated power, etc. of the servers are the same.

[0024] 1) Data center power consumption model

[0025] Currently, the power usage effectiveness (PUE) is often used in data centers to describe the proportional relationship between the power of IT equipment and the total power of the data center. Then the power of data center i at time t is:

[0026] (1)

[0027] Wherein, is the total power consumption of data center i at time t, is the power utilization efficiency of data center i, is the power consumption of IT equipment of data center i at time t.

[0028] The power of IT equipment includes server power and network transmission power. Then the power of IT equipment at time t is:

[0029] (2)

[0030] Wherein, is the power consumed by the servers of data center i at time t, is the network transmission power of data center i at time t. The network transmission power of the data center includes transmission link power and transmission equipment power, and its dynamic range is very small. Therefore, the network transmission power can be regarded as a fixed value.

[0031] The utilization model describes the utilization degree of the server based on the ratio of the workload arrival rate to the service rate, and comprehensively considers parameters such as the number of servers, no-load power, and full-load power to solve the power of the data center server:

[0032] (3)

[0033] Wherein, and are the powers of the active servers of data center i in the idle state and the full-load state respectively, and u is the CPU utilization rate of the active servers.

[0034] According to the different processing characteristics of the data center for the workload, the workload processed by the data center can be divided into delay-sensitive (DS) workloads and delay-tolerant (DT) workloads. Delay-sensitive workloads have higher requirements for the processing time of service responses, usually requiring a delay time within 1 s. While delay-tolerant workloads have lower requirements for the response time of services. According to the deadline required by network users, the delay time of their responses is usually several hours to several days. This chapter establishes a server power consumption model considering the different processing characteristics of these two types of workloads.

[0035] Suppose that data center i has started servers to process delay-sensitive workloads during the t period. The average CPU utilization rate of the servers can be calculated as:

[0036] (4)

[0037] In the formula, is the server CPU utilization rate of delay-sensitive workloads in data center i during period t, is the total number of geographically dispersed front-end proxies, is the number of arrivals of delay-sensitive workloads from the front-end proxy in data center i during period t, is the average service rate of the server in data center i for processing delay-sensitive workloads.

[0038] Suppose that servers are enabled in data center i during period t to process delay-tolerant workload h, and the average CPU utilization rate of the servers can be calculated as:

[0039] (5)

[0040] In the formula, is the server CPU utilization rate of delay-tolerant workloads in data center i during period t, is the number of delay-tolerant workloads h processed and completed in data center i during period t, is the service rate of the server in data center i for processing delay-tolerant workload h.

[0041] Then the power of the servers in data center i during period t can be expressed as:

[0042] (6)

[0043] In the formula, H is the type of delay-tolerant workload.

[0044] 2) Spatiotemporal scheduling characteristics of the data center

[0045] For delay-sensitive workloads, the front-end proxy schedules the workloads spatially according to the power availability information. In the case where the power supply is insufficient to process the workloads, the workloads will be deleted, which will cause losses to the data center operator at this time.

[0046] The allocation constraints of the delay-sensitive workloads arriving at the front-end proxy in each period are shown in the following formula:

[0047] (7)

[0048] In the formula, the total number of arrivals of delay-sensitive workloads at the front-end proxy during period t.

[0049] To calculate the processing delay time of delay-sensitive workloads according to the M / M / 1 queuing model, the following constraints need to be satisfied:

[0050] (8)

[0051] Converted to linear form:

[0052] (9)

[0053] In the formula, D is the maximum processing delay time of delay-sensitive workloads;

[0054] For delay-tolerant workloads, since they generally require a large amount of background data, scheduling between different data centers will sacrifice a large amount of memory and cause bandwidth loss. Therefore, the scheduling ability in terms of time is mainly considered. It is assumed that the same type of delay-tolerant data workloads are evenly distributed to each data center by the balancer. Delay-tolerant workloads should be processed before their deadlines. If they are not completed within the deadline, the workloads will be deleted:

[0055] (10)

[0056] In the formula, is the maximum delay time of delay-tolerant workload h, is the time period when delay-tolerant workload h arrives at data center i, is the total number of delay-tolerant workloads h;

[0057] All delay-tolerant workloads allocated to each time period should be processed:

[0058] (11)

[0059] 3) Interaction strategy between backup energy storage and distribution network in the data center park

[0060] ① First-stage deployment strategy

[0061] When the distribution network is powered off (i.e., ), the power supply of the data center will switch to the backup energy storage to ensure the uninterrupted power supply of the data center. To maintain the high reliability of data center workload processing, the backup energy storage only powers the data center in this stage and does not provide energy storage services for the restoration of the distribution system. That is, there is no power exchange between the data center and the distribution system in this stage.

[0062] In the above scenario, the constraints of the backup energy storage in the first stage are as follows:

[0063] The backup energy storage is in the discharging state in the first stage, and its discharging power should be less than the maximum discharging power:

[0064] (12)

[0065] Where:

[0066] is the discharge power of the first-stage standby energy storage of data center i at time t;

[0067] is a binary variable indicating whether data center i is in the first-stage discharge state at time t;

[0068] represents the maximum charge-discharge power of the standby energy storage of data center i;

[0069] The flag indicating whether the data center park is in the first-stage discharge state is , at this time the distribution network does not supply power to the data center park, that is, the data center is not in a connected state ( ):

[0070] (13)

[0071] In the formula, is a binary variable indicating whether node i is in a connected state at time t.

[0072] Temporal constraint of the state of charge (SOC) of the standby energy storage:

[0073] (14)

[0074] In the formula, is the state of charge of the standby energy storage of data center i at time t, represents the capacity of the standby energy storage of data center i.

[0075] The state of charge of the standby energy storage of the data center in the first stage should not be lower than the minimum state of charge:

[0076] (15)

[0077] In the formula, is the minimum capacity of the standby energy storage required for the reliability of data center i.

[0078] When the standby energy storage works as a power source, its energy storage level is the initial energy storage level before the power outage:

[0079] (16)

[0080] In the formula, is the initial state of charge of the standby energy storage before data center i shuts down.

[0081] The backup energy storage is only used for power supply to the data center at this time, and the discharge power is equal to the power consumption of the data center at this time:

[0082] (17)

[0083] In the formula, is the positive integer M in the big M method.

[0084] ② The second-stage deployment strategy

[0085] When the data center park is initially powered on, the data center park will be powered by the distribution network. At this time, the backup energy storage level in the data center park is at a low level and has no power supply capacity ( ), so the backup energy storage in the data center park will be immediately charged after power-on. In this stage, the power provided by the power distribution system is the sum of the data center operating power and the charging power of the backup energy storage. The charging duration of the second stage depends on the power interruption time. Therefore, the operation behavior of the data center is closely related to the load restoration decision.

[0086] It is assumed in this article that when the data center is re-powered on ( ), the backup energy storage will be charged to its initial energy storage level as soon as possible. Before the energy storage level of the backup energy storage reaches the initial level, the backup energy storage cannot provide energy storage services for the power distribution system. And for the sake of simplicity, it is assumed in this stage that the charging power of the backup energy storage remains unchanged.

[0087] Therefore, the energy storage constraint in the second stage is:

[0088] (18)

[0089] (19)

[0090] (20)

[0091] (21)

[0092] (22)

[0093] (23)

[0094] In the formula, is the availability status of the backup energy storage for the restoration of the power distribution system, is the maximum charging power of the backup energy storage of data center i, is the charging efficiency of the backup energy storage of data center i, is the charge and discharge power of the backup energy storage in the second stage of data center i.

[0095] ③ Third-stage interaction strategy

[0096] After the second stage, the state of charge of the backup energy storage reaches the initial level through continuous charging. Compared with the minimum backup capacity, the additional part of the backup energy storage can be used to serve the distribution system (i.e., help restore the load). Therefore, at this stage, the data center has been fully restored, and the backup energy storage begins to provide energy storage services for the distribution system in the third stage (i.e., ).

[0097] Therefore, the energy storage constraint in the third stage is:

[0098] Once the backup energy storage becomes available, energy storage services can always be provided:

[0099] (24)

[0100] It means that the available time of the backup energy storage in this stage should be later than the power-on time of the data center:

[0101] (25)

[0102] The power of the backup energy storage of data center i at time t in the third stage is:

[0103] (26)

[0104] Wherein, 、 are the charge / discharge power of the backup energy storage of data center i at time t in the third stage, is the power of the backup energy storage of data center i at time t in the third stage.

[0105] The limiting conditions for the backup energy storage providing energy storage services for the distribution system (limiting the magnitude of the charge / discharge power):

[0106] (27)

[0107] (28)

[0108] Wherein, 、 represent the binary variables of the charge / discharge state of the backup energy storage of data center i at time t in the third stage.

[0109] The backup energy storage can only work in the third stage and cannot charge and discharge simultaneously:

[0110] (29)

[0111] When the backup energy storage works as a power source, its energy storage level is the initial energy storage level:

[0112] (30)

[0113] Wherein, is the state of charge of the backup energy storage of data center i at the t-th moment in the third stage.

[0114] The SOC constraint of the backup energy storage is as follows:

[0115] (31)

[0116] (32)

[0117] The charge level of the backup energy storage should be restored to its initial level at the end of the load restoration:

[0118] (33)

[0119] (2)The voltage support strategy during the distribution network restoration stage is described in detail as follows:

[0120] 1) Voltage support for the AC bus

[0121] Available substations, flexible substations, and distributed generators can all provide voltage support for the AC bus in the power outage state. For the safe operation of the distribution system, each AC bus has exactly one voltage source to stabilize the bus voltage.

[0122] (34)

[0123] Wherein, is the square of the provided AC support voltage, is the square of the AC support reference voltage, is a binary variable indicating whether to provide AC support voltage (1 means providing voltage support), is the set of AC nodes connected to the FS, is the set of AC nodes connected to the substation, is the set of AC nodes connected to the distributed generator.

[0124] According to the operating characteristics of the flexible substation, when the AC bus lacks voltage support and the DC bus is in normal operation at this time, that is, when the data center park on the DC bus is powered on, that is when, the flexible substation can provide voltage support for the AC bus ( ); when the node is located on the energized branch and is connected to the flexible substation, that is, when the AC bus is in normal operation at this time, the flexible substation operates in the power adjustment mode ( ), that is, the AC terminal of the flexible substation does not provide voltage support for the connected AC nodes. When all the nodes connected to the distributed generator are in the power-off state, the distributed generator will provide voltage support ( ) When a node is connected to a substation node, even if it is on an energized branch, the substation should provide voltage support preferentially. At this time, the flexible substation and the distributed generator switch to the power adjustment mode.

[0125] (35)

[0126] In the formula, is the set of power-off AC nodes, is the nodes connected to the same flexible substation m, is the nodes connected to the same distributed generator m, is the set of AC branch nodes, is the set of power-off AC branch nodes.

[0127] 2) DC low-voltage bus voltage support

[0128] Since only the flexible substation is related to the DC node, this section only considers the voltage support of the flexible substation. During the restoration period, the DC terminal of the flexible substation can stabilize the DC voltage. For the radial topology, there is a unique voltage source on the DC bus. According to the operating characteristics of the flexible substation, when the DC bus lacks voltage support and the AC bus is in normal operation at this time, the flexible substation will provide voltage support. At this time, the data center in the first stage will enter the operation of the second and third stages.

[0129] (36)

[0130] In the formula, is a binary variable indicating whether to provide DC support voltage (1 means providing voltage support), is the set of all DC nodes.

[0131] For the DC node, when the AC node connected by the same flexible substation is in the energized state, it will definitely get the voltage support of the flexible substation.

[0132] (37)

[0133] 3) Cooperation between AC and DC buses

[0134] Only when any terminal of the flexible substation is connected to a normally operating bus can the flexible substation terminal actively maintain the node voltage. Since only two ports of the flexible substation are considered in this article, the flexible substation can only provide DC voltage support or AC voltage support, and cannot provide both at the same time.

[0135] (38)

[0136] (3)Consider the post-disaster restoration modeling of the power distribution network in the data center, which is described in detail as follows:

[0137] 1) Objective function

[0138] The main objective of the present invention is to minimize the total power outage loss of the data workload decline in the data center and other unrecovered power loads during the power supply restoration process.

[0139] (39)

[0140] In the formula, is the economic loss of the data center, is the economic loss of other loads, is the economic loss of the flexible substation.

[0141] The economic loss of the data center is as follows:

[0142] (40)

[0143] In the formula, is the price of the data received by the data center.

[0144] The loss of other loads is measured by the electricity price:

[0145] (41)

[0146] In the formula, is the price of the active power purchased from the upper-level power grid, is the load recovery rate, represents the load weight, is the active power of the load at node i at time t.

[0147] (42)

[0148] 2) Constraint conditions

[0149] ① Power flow constraint

[0150] In this section, the Distflow power flow branch power flow model is adopted, and the AC node power flow constraints are shown in (43)-(49):

[0151] In this part, the lines are all AC lines, that is respectively represent flowing from i to j and from k to i.

[0152] The node voltage amplitude constraint is as follows:

[0153] (43)

[0154] (44)

[0155] (45)

[0156] (46)

[0157] (47)

[0158] (48)

[0159] (49)

[0160] Wherein, 、 represent the square of the voltage of the corresponding node, represents the square of the current of the line, 、 represent the active / reactive power of the line at time t, 、 represent the resistance and reactance of the line, 、 represent the active / reactive power transmitted from node k to node i, 、 represent the active / reactive power transmitted from node i to node j, 、 is the active / reactive power of the distributed generator at node i at time t, 、 is the active / reactive power of the load at node i at time t, is a binary variable indicating whether the load is in use, 、 are the squares of the upper / lower limits of the node voltage, 、 are the upper / lower limits of the active power that the line can withstand, 、 are the upper / lower limits of the reactive power that the line can withstand.

[0161] The DC node power flow constraints are shown in (50)-(54):

[0162] (50)

[0163] (51)

[0164] (52)

[0165] (53)

[0166] (54)

[0167] In the formula, is a binary variable for restoring the availability status of the standby energy storage for dispatching.

[0168] ② Power restoration constraint of the power load

[0169] The restoration rate of the load during a power outage is restricted by the operating status of the node where it is located. When the node is on the restoration path ( = 1), the load of the node can be restored. Its load restoration rate depends on the availability level of the power and the weight of the load.

[0170] (55)

[0171] (56)

[0172] (57)

[0173] ③ Operating constraints of distributed generators

[0174] Distributed generators have capacity and ramping constraints, which are specifically described as follows:

[0175] (58)

[0176] (59)

[0177] (60)

[0178] In the formula, , are respectively the upper and lower limits of the active power output of the distributed generator, are respectively the active power of the distributed generator at node i at time t, , are respectively the upper and lower limits of the active power output of the distributed generator, are respectively the active power of the distributed generator at node i at time t, is the ramping rate limit of the power of the distributed generator.

[0179] ④ Emergency operation constraints of the data center park

[0180] The emergency operation constraints of the data center park are as constrained in the first section. In addition, there are constraints on the workload and the number of active servers:

[0181] (61)

[0182] (62)

[0183] (63)

[0184] In the formula, is the total number of servers in data center i.

[0185] ⑤ Operating constraints of the flexible substation

[0186] The basic structure of the flexible substation is as Figure 1 shown. According to the schematic diagram of the converter structure inside the four-port flexible substation, in this section , the operating model of the flexible substation is as follows:

[0187] The power balance constraint of the flexible substation is as follows:

[0188] (64)

[0189] In the formula, is the active power output from port 1 on the AC side of the flexible substation at node g at time t, is the active power output from port 2 on the DC side of the flexible substation at node i at time t, is the active power loss of the AC / DC converter in FS, is the active power loss of the DC / DC converter in FS.

[0190] The loss caused by the AC / DC converter is as follows:

[0191] (65)

[0192] In the formula, is the active power loss of AC port 1 of FS, is the loss coefficient of the AC / DC converter in the flexible substation.

[0193] The loss caused by the DC / DC converter is as follows:

[0194] (66)

[0195] In the formula, is the loss coefficient of the DC / DC converter in the flexible substation.

[0196] The capacity constraint of the DC terminal is as follows:

[0197] (67)

[0198] In the formula, is the capacity of the DC / DC converter in the FS.

[0199] Since the FS realizes the electrical isolation of the connected feeder, the reactive power output at the AC side is independent and needs to satisfy the following capacity constraints:

[0200] (68)

[0201] In the formula, are the upper and lower limits of the reactive power of the AC / DC converter in the flexible substation, is the reactive power of DC port 1 in the flexible substation.

[0202] The capacity of the AC port is constructed as a cone constraint:

[0203] (69)

[0204] In the formula, is the reactive power output of the AC port in the flexible substation, is the capacity of the AC / DC converter in the flexible substation.

[0205] ⑥ Radial topology constraints of the flexible distribution network

[0206] The following formula is the time sequence constraint of the node power supply state. Once the node is powered on, it will remain connected subsequently:

[0207] (70)

[0208] The following formula restricts the switching ability of the branch. Only the switch line can change the state. The non-switch branches remain in the original state. Considering the following formula can reduce the scale of variables and conform to the limitations of the actual distribution network switch installation:

[0209] (71)

[0210] In the formula, represents the binary indicator of the connection state of the distribution line between node i and node j at time t (if connected, it is 1), represents the binary indicator of whether there is a physical connection (distribution line) between node i and node j (if so, it is 1).

[0211] (72)

[0212] In the formula, is a binary indicator variable used to indicate whether a remote switch is equipped in the line between node i and node j (if so, it is 1).

[0213] For a connected branch, its connection direction is unique:

[0214] (73)

[0215] In the formula, 、 are connection direction indicators. When node j is the child node of node i, then and .

[0216] (74)

[0217] For a connected node ( ), there is exactly one parent node (i.e., there is no loop network in the recovery process). To ensure the radiation degree, if the node is directly connected to an available substation or voltage support is provided by a flexible substation or a distributed generator ( ), the relevant direction indicator will be forced to zero:

[0218] (75)

[0219] ⑦ Radial topology constraints based on the modified virtual network

[0220] Based on the radial topology of the modified virtual network, a modified virtual network is constructed to describe the flexible radial recovery structure with flexible substations and distributed generators. A set of virtual energy variables is introduced to reveal the connection order of branches and nodes. The following formula maps the physical connections and operating states between nodes, branches, flexible substations, distributed generators, and substations to the virtual network.

[0221] The virtual energy flow limit on the line is as follows:

[0222] (76)

[0223] (77)

[0224]

[0225] In the formula, is the virtual energy flowing from node i to j.

[0226] The virtual energy limit of the FS connection node is as follows:

[0227] (78)

[0228] In the formula, is the virtual energy flowing from the flexible substation to node i.

[0229] The virtual energy limit for the substation-connected nodes is as follows:

[0230] (79)

[0231] In the formula, is the virtual energy flowing from the substation to node i.

[0232] The virtual energy limit for the distributed generator-connected nodes is as follows:

[0233] (80)

[0234] In the formula, is the virtual energy flowing from the substation to node i.

[0235] The voltage source node starts the restoration path as a virtual source, and the source node can provide virtual energy for other nodes. Branches and flexible substations transfer virtual energy to each non-source child node with a virtual load:

[0236] (81)

[0237] In the formula, represents the set of parent nodes of node i, represents the set of child nodes of node i.

[0238] The available substations and distributed generators can be virtual sources for the entire system. There may be multiple voltage source selections. Nodes and branches can be divided into several restoration paths, but there should be at least one voltage source in the entire network.

[0239] (82)

[0240] To ensure the radial condition of each path, the following constraints are added based on graph theory:

[0241] (83)

[0242] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0243] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the various embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for high-resilience coordinated operation of a data center and a distribution network, characterized in that: The steps include: (1) Establish an emergency operation model for the data center park during the distribution network recovery phase: Establish an emergency data flow scheduling model for the data center and a backup energy storage allocation strategy for the data center park. The basic structure of the data center park includes the data center body, backup energy storage, and a flexible substation. During the emergency operation of the data center park, the power demand of the data center is changed through the spatiotemporal transfer of the data center workload, and the backup energy storage is deployed to provide power support for the data center, and help the distribution system restore critical loads when power is restored; the emergency data flow scheduling model for the data center includes a data center power consumption model and a data center workload time-space scheduling model. The data center power consumption model uses the CPU utilization model and uses power utilization efficiency to characterize the proportional relationship between IT equipment power and the total power of the data center. The IT equipment power considers the processing power consumption of delay-tolerant workloads and delay-sensitive workloads. The data center workload time-space scheduling model considers the spatial scheduling and workload deletion constraints of delay-sensitive loads, as well as the time scheduling and workload deletion constraints of delay-tolerant loads; the workload deletion constraint means that if it is not worth using computing resources or exceeds the computing power or delay time requirements of the data center, the data load will be deleted; (2) Establish a voltage support strategy based on flexible substations and distributed generators: After the distribution network fault is isolated, consider the voltage support role that the flexible substation and distributed generator can play for the bus. Consider that the flexible substation and distributed generator are in two working states, namely power regulation mode and voltage support mode. For the flexible substation, when the busbars on both sides are in normal operation, the flexible substation operates in power regulation mode to realize the power interaction of the AC and DC busbars; when one side of the busbar is operating normally, the flexible substation operates in voltage support mode to provide voltage support for the power-off busbar. For distributed generators, when the adjacent nodes are in a power-off state, they will operate in voltage support mode to provide voltage support for the power-off nodes; if both are operating normally, they will be in power regulation mode, and the flexible substation terminal and distributed generators will provide voltage support and assist the available substations; (3) Modeling of post-disaster recovery of the distribution network considering the data center: After the emergency operation model of the data center park and the voltage support strategy based on flexible substations and distributed generators are established, the model parameters are delivered to the distribution network operator for integration, and the distribution network flow constraints and distribution network radial topology constraints are added to merge them into a recovery strategy model for the entire distribution network. The distribution network operator will jointly solve the model to achieve the recovery of key loads in the distribution network.

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