Wellsite electrical power management system

A method includes supplying a plurality of generators, each generator in electrical communication with a switchgear with each switchgear in data communication with a generator data management system. The method also includes supplying a plurality of electrically driven fracturing pumps with each electrically driven fracturing pump in data communication with pump data management system. Further, the method includes supplying a load shedding system, the load shedding system in data communication with the generator data management system and a pump control system, the pump control system in data communication with the pump data management system. The method includes determining which pumps should have speed reduced by the load shedding system and reducing the speed of the pumps determined by the load shedding system using the pump control system.

BACKGROUND

Wellsite operations, in particular, electrically driven fracturing pumps and other electrically powered equipment onsite including, but not limited to, blenders and CAS units, place demands on the generators located on-site. Typically, one or more generators provide electrical power to one or more switchgear units. The switchgear units in turn distribute electrical power to on-site systems such as the electrically driven fracturing pumps, slurry pumps and other devices. If an electrically-powered element of one or more of the on-site systems draws electricity in excess of what can be provided by the one or more generators or one or more switchgear units, circuit protection of the switchgear will trip, resulting in shutting down of the associated generator. Because a single generator may provide power to more than one unit, the draw by an electrically powered element may cause several on-site systems to cease operations.

SUMMARY

In certain embodiments, a method is disclosed. The method includes supplying a plurality of generators, each generator in electrical communication with a switchgear with each switchgear in data communication with a generator data management system. The method also includes supplying a plurality of electrically driven fracturing pumps with each electrically driven fracturing pump in data communication with pump data management system. Further, the method includes supplying a load shedding system, the load shedding system in data communication with the generator data management system and a pump control system, the pump control system in data communication with the pump data management system. The method includes determining which pumps should have speed reduced by the load shedding system and reducing the speed of the pumps determined by the load shedding system using the pump control system.

DETAILED DESCRIPTION

FIG.1depicts a frac site5including generator domain20, electrical power management system (EPMS)10and pump domain40, all in data communication with one another. Generator domain20may include plurality of generators22in electrical communication with switchgear24. While shown as a single set of generators22and a single switch gear24, one of ordinary skill in the art with the benefit of this disclosure will understand that generator domain20may include multiple sets of generators22corresponding with multiple switch gears24. Generators22are in data communication with generator data management system26. Generator data management system26monitors the status of generators22, including power output, generators running and not running, and status of generators22. Generator data management system26includes non-transitory computer readable medium having instructions stored thereon. Generator data management system26is in data communication with load shedding system16, further described herein below.

As further shown inFIG.1, pump domain40includes electrically driven fracturing pumps42. Electrically driven fracturing pumps42are in data communication with pump data management system44. Pump data management system44monitors which of electrically driven fracturing pumps42are in operation, the speed at which electrically driven fracturing pumps42are operating, and the status of electrically driven fracturing pumps42. Pump data management system44includes non-transitory computer readable medium having instructions stored thereon. Pump data management system44is in data communication with pump control system14, further described herein below.

Pump control system14and load shedding system16are in data communication with communications hub12. Communications hub12includes an operator interface for setup and communication management of the operation of electrically driven fracturing pumps42, generators22, electrically driven blending units62, described further hereinbelow, CAS units, hydrators, data van, and other frac site equipment. Communications hub12may include software, or hardware and software. Communications hub12further provides a pathway for data and commands between pump control system14and load shedding system16. The combination of communication hub12, pump control system14, and load shedding system16comprise electrical power management system (EPMS)10. In certain embodiments, EPMS10may be housed in a data van. In other embodiments, EPMS10may be a static system.

As depicted inFIG.2, central communication hub12coordinates communications between the domains. In the example shown inFIG.2, those three domains are generator domain20, pump domain40and slurry domain60. As described above with respect toFIG.6, pump domain40includes electrically driven fracturing pumps42, pump data management system44, and pump control system14. Slurry domain60includes electrically driven blending units62, which provide slurry to pump domain40and blending operational control64. Generator domain20includes generators22, switchgear24, generator data management system26, and load shedding system16.

Criteria for load shedding system16may be established based on individual generator22capacity and power needs of the electrical motors of electrically driven fracturing pumps42receiving power from that individual generator22. Non-limiting examples of loading shedding algorithms100used in load shedding system16are depicted inFIGS.3aand3b.FIG.3adepicts unit priority load shedding algorithm110. In unit priority load shedding algorithm110, an operator sets the threshold value for maximum power capacity (Pmax) (112) for a generator22. The operator further sets the priority sequence of frac units for speed reduction, i.e., electrically driven fracturing pumps42(114). Load shedding system16measures the total power demand (Pd) against the total power capacity (116). If Pmax has not been reached by Pd, load shedding system16continues to measure Pd. If Pmax is reached (118), load shedding system16sends pump control system14a speed reduction command to electrically driven fracturing pumps42to reduce speed to on particular electrically driven fracturing pumps in the order previously designated by the operator (120). After the speed has been reduced to the designated speed for electrically driven fracturing pumps42, load shedding system16again measures Pd against Pmax (116). Further, when Pd has reached Pmax, load shedding system16may prevent additional electrically driven fracturing pumps42from starting.

In another example of a load shedding algorithm, unit demand load shedding algorithm130is depicted inFIG.3a. In unit demand load shedding algorithm130, an operator sets the threshold value for maximum power capacity (Pmax) (112) for a generator22. Loading shedding system16measures Pd against power capacity (Pc) of each electrically driven fracturing pump (42) (132). If Pmax has not been reached, load shedding system16continues to measure Pd against Pc. If Pmax has been reached (118), load shedding system16measures Unit Power Demand (UpD) of electrically driven fracturing pumps42based on unit power (kW) and sets a highest unit power demand priority sequence according to highest to lowers unit power, i.e., each electrically driven fracturing pump (42) (134). Pump control system14sends a speed reduction command to electrically driven fracturing pump (42) according to highest unit power demand sequence, i.e., (UpD1to UpDn) (136).

In yet another embodiment of a load shedding algorithm, unit efficiency load shedding algorithm140is depicted inFIG.3b. In unit efficiency load shedding algorithm140, an operator sets the threshold value for maximum power capacity (Pmax) (112) for a generator22. The operator further sets a threshold value for minimum unit power efficiency (Upe) for each electrically driven fracturing pump (42) (142). In certain embodiments, Upe is defined as HHP/HPe (hydraulic horsepower/horsepower electric) which may be calculated by (Flow GPM*Pressure psi/1714)/KW/0.746. Loading shedding system16measures Pd against power capacity (Pc) of generator22(132). If Pmax has been reached (118), load shedding system16measures Upe and sets a priority sequence (lowest unit efficiency sequence) according to a minimum Upe (UpeMin) from lowest to highest UpeMin (146). Pump control system14sends a speed reduction command to electrically driven fracturing pump (42) according to lowest unit efficiency sequence (Upe1to Upen) (148).

In another embodiment of a load shedding algorithm, unit power condition algorithm150is shown inFIG.3b. In unit power condition algorithm150, an operator sets the threshold value for maximum power capacity (Pmax) (112) for a generator22. An operator further sets the threshold value for Unit Apparent Power (UpS) (152). Unit Apparent Power (kVA) is defined as the total power effect on the generator. It is the vector sum of real power in kW and reactive power, kVAR.

Loading shedding system16measures Pd against power capacity (Pc) of generator22(132). If Pmax has been reached (118), load shedding system16measures UpS and sets a priority sequence according to UpS (highest to lowest) (152). Pump control system14sends a speed reduction command to electrically driven fracturing pump (42) according to the priority sequence (UpS1-UpSn) (154).

In each of embodiments of the load shedding algorithm, once the command has been sent from pump control system14, to electrically driven fracturing pumps42to reduce speed, electrically driven fracturing pumps42reduce speed as directed by the command.

In addition to controlling the speed of electrically driven fracturing pumps42, load shedding system16may preclude the bringing online of additional electrically driven fracturing pumps42when the monitored generator22is already at the predetermined threshold. In another embodiment, the power demand of each electrically driven fracturing pump42may be stored within the pump data management system44. If upon receiving a signal to initiate operation of an electrically driven fracturing pump42, load shedding system16determines that the known power demand for initiating operation will exceed the predetermined threshold, then load shedding system16will preclude the bringing online of additional electrically driven fracturing pump42.

In addition to controlling the speed of the electrically driven fracturing pumps42, load shedding system16may control electrically driven support equipment, such as, but not limited to, blending units62, CAS units, hydrators, and equipment associated with the operation of electrically driven fracturing pumps42in data communication with a support equipment data management system66. As described above with respect to load shedding system algorithms shown inFIGS.3and3b, load shedding system16may shut down support equipment in accordance with the priority algorithms.