FIELD

The present disclosure relates generally to methods and systems for power generation, generators, and management and control thereof. More specifically, embodiments of the present disclosure comprise hybrid generator systems and micro-grid applications.

BACKGROUND

Various methods and systems for “hybrid” power systems are known. As used herein, “hybrid” generally refers to systems that combine conventional gas-powered or engine-drive power generation devices with power electronics and battery storage. Hybrid systems are known to be used in power applications including automobiles and transportation systems where the range and efficiency of a gas-powered engine is enhanced. Such systems include those shown and described in U.S. Patent Application Ser. No. 2011/0120789 to Teraya, which is hereby incorporated by reference in its entirety.

Hybrid systems are also known in power generation applications as a means to improve efficiency. Typically, these hybrid power systems are designed to operate as a conventional generator during normal, relatively high-power demand cycles and operate solely on stored energy (e.g. battery power) during periods of reduced power demand. This provides a means to improve efficiency, reduce fuel consumption, and/or operate in “stealth mode” with a much lower heat and noise signature.

Hybrid technologies can further be used to provide supplemental power to generators during peak loading. This momentary “battery assist” to the engine-driven generator can significantly improve peak load capability or reduce a required size of the generator for applications with relatively high peak loads and much lower normal operating loads. Known hybrid systems provide power support during various modes of operation such as a hybrid vehicle that maintains vehicle accessories and “creeps” in traffic on stored energy and then provides supplemental power when overtaking traffic or accelerating onto a freeway.

Hybrid generators used in power generation applications differ from vehicle applications in various ways. For example, hybrid generators for power generation typically operate at a substantially fixed speed (e.g. 1,800 RPM or 1,500 RPM depending on desired output frequency). As load is applied to the generator, power electronics can provide power from a stored energy source (e.g. a battery) to assist the engine.

SUMMARY

Accordingly, embodiments of the present disclosure contemplate and provide methods and systems for hybrid generators including conventional or gas-fired engines and a supplemental energy source such as an energy storage module (“ESM”).

In various embodiments, hybrid power systems are provided that support a range of power levels of a base engine-drive generator. In certain embodiments, this support is provided by a generator system that comprises a stored energy source (e.g. a battery). The stored energy source is contemplated as comprising the sole power source from which the generator system provides power under light load conditions. Additionally, the stored energy source provides supplemental power or support for an engine of the generator during peak load conditions. Such support is contemplated as preferably comprising short, high-load transient steps. Further, the stored energy source is operable to provide power quality or power conditioning at various different power loads, including periods of normal load(s).

In one embodiment, a hybrid generator system or device is provided that comprises a generator with a peak power generation capacity of 410 kW. The hybrid generator comprises an 11-liter gaseous fueled generator integrated with an ESM. The ESM comprises a 500 kVA bi-directional multi-port inverter and a 120 kWh lithium-ion battery with a continuous 2 C charge/discharge rating and 3 C peak rating. The hybrid generator system is contemplated as being integrated with other three-phase power sources, and/or renewable energy resources in both grid-parallel and grid-isolated modes. It will be recognized, however, that various system, devices, and methods of operation disclosed herein are not limited to a particular gaseous fueled power unit or to any particular ESM. Various inventive aspects of the present disclosure are provided and detailed herein that are not limited to an engine, ESM or other device of any particular specification or capabilities. It is contemplated that various alternatives to the foregoing devices are provided, particularly (but not limited to) applications and situations where it is desirable to scale the power and performance requirements of a generator unit up or down.

In various embodiments, an ESM is provided that comprises a separate, stand-alone system providing solid-state support to any conventional generator or other source of electrical power. In certain embodiments, the ESM is contemplated as comprising a 360 kW peak, 240 kW continuous power output at a continuous 480V.

In certain embodiments, hybrid generator systems of the present disclosure are provided with application-specific output requirements for voltage and frequency. For example, a Baker Hughes Electrospeed Advantage Variable Speed Drive commonly used in oil field submersible pump applications specifies a voltage tolerance on a 480V 3-phase system of +5% to −15% (504V-408V) and a frequency tolerance of +/−2 Hz (58 Hz-62 Hz). Embodiments of the present disclosure provide an ESM that is operable to be programmed to operate under all load conditions within the requirements of such a device, and such that the voltage and frequency output of the ESM is always within the tolerances of such a device.

In various embodiments, inverter “droop tuning” of a generator system is provided. Specifically, in certain embodiments, an inverter associated with and/or in communication with an ESM comprises the ability to anticipate or react to a droop, reduction or drop in a generator speed (i.e. RPMs) in a quicker and more efficient manner than a conventional gas-fired engine could react to such a droop. Conventional gas-fired generators may comprise the ability to detect a reduction in RPM when an increase in load is applied. After this reduction is detected, a signal may be generated to increase a throttle and restore generator speed. This reactionary approach provides a slow response, particularly when coupled with the delays associated with increasing a throttle to the time a desired engine speed is restored. In some embodiments, systems of the present disclosure are operable to detect an increase in load or demand and the inverter of an ESM is operable to provide power or current to the generator in anticipation of or response to a droop event. In some embodiments, the ESM reacts to a droop after the droop has been experienced, and wherein reaction time to restore engine speed is still reduced relative to conventional systems that rely solely on throttling a gas engine to accommodate changes in load.

In various embodiments, a dynamic load is used to establish the AC input characteristics to a system (for example, from a generator, renewable sources, and/or the grid) and inverter tuning is optimized to match the input characteristics. In some embodiments, generator systems of the present disclosure comprise artificial intelligence of “active learning” features wherein an ESM controller monitors AC input response and auto-corrects to continuously optimize tuning as the AC input performance varies.

In various embodiments of the present disclosure, hybrid generators are provided that comprise a programmable energy output using direct or interactive tuning to integrate controlled generating resources. In some embodiments, hybrid generator systems are provided that comprise self-determining and integration of energy resources, including controlled resources (e.g. generators). In some embodiments, non-controlled (e.g. renewable) energy resources and utility power is provided to generator systems. In various embodiments, one or more active-learning functions is provided that allow(s) for the system to adjust to inevitable variability in generating resources.

Devices and systems of the present disclosure integrate the performance tuning curves of an inverter drive (i.e. power from an ESM) and an engine-driven generator. In such embodiments, the inverter and the generator comprise respective tuning set points and curves that define how each system responds to deviations in voltage and/or frequency. In order to have a balanced system in hybrid mode that relies on an optimal power response from each system providing power it is necessary to modify the tuning parameters of each contributing system. This allows a hybrid system to deliver optimum performance from each system and thus the maximum and optimum energy performance as a combined and balanced hybrid power system. It is contemplated, for example, that systems of the present disclosure are incorporated into a renewable energy resource that supplies a majority of demand to a load, with a balance of needed power being provided by a utility grid, and wherein a generator is provided to service emergency or peak load situations. Under certain energy load and cost scenarios, the generator is operable to provide supplemental power to the load or application rather than relying on utility support. ESM controllers of the present disclosure are operable to command the generator to operate in this way so as to reduce dependence from the grid and/or automatically select or prioritize a power generating source based on price per kW-hr.

In various embodiments, hybrid generator systems are provided with direct tuning control technology that allow for active and direct tuning and adjustment of each controller responsible for each respective generating source (i.e. each control device may be directly programmed and/or reprogrammed).

In various embodiments, generator systems of the present disclosure comprise control systems that allow for interactive tuning, particularly where access to a controller of a generating source is not available or possible. In such embodiments, an ESM is provided that can be operated in a mode wherein the ESM is connected to the generating source and does not have access to the tuning parameters in the generator controller. The ESM is operable to command, sense and map a series of known load steps delivered to an onboard battery energy storage. An ESM controller is operable to adjust its own tuning to match a fixed tuning setting of a generating source. In such embodiments, an ESM is provided that is operable to integrate and “hybridize” virtually any generator.

In various embodiments, generator systems of the present disclosure are capable of integration with multiple energy resources including, but not limited to, engine-driven generators, renewable energy systems and pre-existing utility power supply from the grid. In such embodiments, an auto-determining function is provided. Auto-determining functions of the present disclosure comprise various features including, for example, a throttle control that responds to power demands. In such embodiments, a load step is commanded from an ESM controller and the response and “droop curve” of the system is typical of a controlled generating source. The ESM controller is operable to detect a load step before or after generator speed has been impacted, and supply additional power from the ESM (e.g. batteries) to accommodate the load. The ESM controller further comprises the ability to recognize a decrease in load or demand, and reduce a supplemental power supply.

Various renewable energy resource, such as photovoltaics, do not typically have the ability to adjust or throttle based on load demands. In other words, the power output of such devices is generally unresponsive to changes in load. In various embodiments of the present disclosure, an ESM controller is provided that is operable to determine that a non-controllable energy resource (e.g. a solar panel) is connected based on a lack of active response to power demands from the ESM.

Generator systems of the present disclosure are further capable of recognizing when a power source comprises a utility power source (i.e. the grid). Utility power comprises a near-infinite response to power commands with no appreciable “droop curve.” ESM controllers of the present disclosure are capable of analyzing such information and recognizing the absence of a droop curve as the indication of an incoming utility power. The same logic and functionality are applied to large (e.g. multi-MW) generating devices and assets. Auto-determining functions and features of the present disclosure are capable of allowing systems of the present disclosure to operate as self-forming micro-grid systems that are capable of making decisions based on resiliency and energy costs to provide a more robust and cost-effective system and reduce the need for human intervention.

Embodiments of the present disclosure provide generator systems that comprise active-learning functions that adjust tuning parameters and correct the interaction of generating resources by monitoring and recording each significant loading or unloading event. By comparing these events, the interaction tuning of the inverter is adjusted in real time such that the system's reliability, performance, and efficiency are constantly maintained at the peak level of performance. In this way, as a generating resource advances through its life-cycle and normal degradation in performance occurs, the system will compensate and continue to function at peak performance and reliability. In the same way, a fast-occurring event, such as a “dead cylinder” from a failed spark plug will allow the system to correct for this situation. Parameters can be set to limit how much active compensation can occur.

In various embodiments, generator systems are provided that vastly improve power quality and power delivery while reducing the total greenhouse gas emissions. Embodiments of the present disclosure reduce emissions by enabling the use of a much smaller engine-driven generator that is matched to a continuous load instead of a peak load. Engine efficiency is improved by operating only at the ideal power nodes, thereby provided the added benefit of improving engine reliability and durability. Power delivery and power quality is significantly improved and supports loads sensitive to voltage and frequency deviation through the programmable, solid-state output of an ESM. Embodiments of the present disclosure further provide for integration and connectivity to renewable energy resources with a controlled, commanded distributed energy resource such as an engine-driven generator and the ability to operate in a grid-independent and a grid-connected mode. Various embodiments and systems provided herein transform a distributed energy resource into a sophisticated, deployable, self-forming microgrid with myriad uses and applications.

Generator systems and ESMs of the present disclosure are contemplated for use in various applications. In some embodiments, an ESM is provided to support a single generator that provides power to an application (e.g. a downhole pump for oil and gas applications, a hospital or other building that has lost a connection to a municipal grid, etc.). In further embodiments, it is contemplated that devices, methods and systems of the present disclosure are employed as grid support systems. In such grid support systems and embodiments, it is contemplated that one or more ESMs (with or without an interconnected generator) are connected to a power generation source. In some embodiments, at least one ESM is provided in combination with a photovoltaic array that is operable to provide electric power. As one of skill in the art will recognize, the output from a photovoltaic array typically comprises a variable output with respect to voltage, frequency and/or current, at least in part due to environmental conditions and the variable nature of the amount of solar energy that is received by the array over time. This variability can present problems for the grid, the grid service provider, and the end-users and devices that are provided with power from the photovoltaic array. Accordingly, in some embodiments, at least one ESM is provided in connection with a photovoltaic array and the ESM serves to provide frequency support, buffering, and signal conditioning for the photovoltaic array. The ESM preferably comprises a programmable frequency output such that an output frequency of the system (including power provided by the grid and/or photovoltaic array) is provided at a constant (e.g. a user-selected 60 Hz). As shown and described herein, the ESM comprises an inverter, an inverter controller and a battery management system (“BMS”) that is capable of and operable to regulate the output frequency. The ESM removes variability at least in an output frequency of an electric power supply. As one of ordinary skill in the art will recognize, the foregoing example related to a photovoltaic power supply is provided as one example of variable loading that can be addressed and improved by embodiments of the present disclosure. Devices, system, and methods of the present disclosure are not limited to any particular application. For example, it is also contemplated that devices, systems and methods of the present disclosure are also employed in a wind farm application wherein power supply from wind patterns may result in similar variability from an electrical power generation source.

In various embodiments, systems of the present disclosure including ESMs can be modified and programmed to function with various different systems and devices. Specifically, an ESM of the present disclosure can be programmed and required to maintain specific operating parameters of interconnected devices. For example, an ESM can be programmed such that a frequency output of an associated generator is maintained within a specific range (e.g. 59.8 Hz and 60.2 Hz), and the controller is operable to control the ESM to dispense and convey power as needed to maintain this generator frequency output.

In various embodiments, systems of the present disclosure comprise at least one ESM and at least one generator provided in combination and in communication with one another. It is contemplated that generators of the present disclosure, including known pre-existing generators comprise a built-in controller that is operable to respond to changes in power demand and increase or decrease a throttle and engine speed to increase and decrease power output, for example. In some embodiments of the present disclosure, an ESM is provided in combination with such a device wherein the ESM comprises an inverter, controller and related logic that is capable of responding quickly to changes in load and demand. In preferred embodiments, the controller and logic of the generator is not deactivated, but is supplemented by the ESM features and wherein the ESM response to a droop curve (i.e. drop in generator frequency) is faster than a similar response that would otherwise be provided by the generator.

In various embodiments of the present disclosure, auto-determining features are provided within ESMs that are operable to determine a type of power supply that the ESM is connected to. For example, controllers and logic are provided with ESMs of the present disclosure that are operable to detect, monitor, and analyze a power supply's response to a demand from the ESM. For example, when an ESM is connected to a power source and signals a demand to the power source for an increase in power, the ESM is operable to recognize if and when the response from the power supply is a steady output. Such a response from the power supply indicates that the power supply is a renewable source (e.g. a photovoltaic field or wind farm) that is simply not capable of quickly increasing a power supply. Further, if the response from the power supply comprises an infinite response such that power demanded is supplied on a relatively short timescale, the ESM is operable to recognize this response and determine that the power supply is the utility grid. Based on the results and determinations of the auto-determining features, systems of the present disclosure are further operable to adjust an output or “droop” curve.

In one embodiment, a hybrid generator system is provided. The system comprises an energy storage module comprising at least one battery for receiving, storing and distributing electrical power; a generator in communication with the energy storage module; and an inverter in communication with the energy storage module. The inverter comprises a bi-directional inverter that is operable to transmit and receive electrical power to and from the energy storage module and the generator in the form of a current. A controller is provided that is operable to receive and transmit information from at least one of the energy storage module, the inverter, the battery, and a grid.

In various embodiments, methods of operating systems of the present disclosure and providing electrical power are provided. In one embodiment, a method of providing electrical power is provided wherein the method comprises providing a hybrid generator system comprising: an energy storage module comprising at least one battery; an inverter in communication with the energy storage module; a controller that is operable to receive and transmit information from at least one of the energy storage module, the inverter, the battery, the generator, and a grid. At least one of an output voltage, current and frequency of the generator is continuously monitored by the controller, and an amount of power being distributed by the energy storage module is increased or decreased based on at least one of an output voltage, current and frequency of the generator dropping below or exceeding a predetermined value or based on an observed rate of change of at least one of an output voltage, current and frequency of the generator. For example, if a rate of change of a generator voltage value is identified as indicating a sudden increase in load, the ESM may be activated. At least one of an output voltage, current and frequency of the generator are monitored for a return to a predefined normal operating status, and the amount of power being distributed by the energy storage module is reduced or terminated based on such a condition being satisfied.

In some embodiments, systems are provided that are configured to monitor and record loading and unloading events. The controllers and logic provided to the generator system or devices of the present disclosure are operable to monitor, record, detect, predict, and determine when a loading or unloading event will affect the generator system. The generator system can use this recorded historical data, alone or in combination with other recorded data, to anticipate and preemptively-respond to a predicted loading or unloading event. For example, a generator system of the present disclosure is operable to anticipate that a sharp, prolonged load will be placed on the generator system at a certain time of day; in order to meet the power requirements of this load the generator system can slowly and efficiently increase its power output to the predetermined time, such that when the predicted load is placed on the generator system the power profile of the generator system does not change significantly. Furthermore, generator systems of the present disclosure can also anticipate an unloading or ramping down event and adjust accordingly. In order to meet the energy demands during an unloading or ramping down period, systems of the present disclosure can efficiently reduce power output of the generator while increasing power output of the ESM to accommodate demands during a contemplated ramp-down of the generator. The Summary is neither intended nor should it be construed as being representative of the full extent and scope of the present invention. The present invention is set forth in various levels of detail in the Summary of the Invention as well as in the attached drawings and the Detailed Description of the Invention and no limitation as to the scope of the present invention is intended by either the inclusion or non-inclusion of elements or components. Additional aspects of the present invention will become more readily apparent from the Detailed Description, particularly when taken together with the drawings.

The above-described embodiments, objectives, and configurations are neither complete nor exhaustive. As will be appreciated, other embodiments of the invention are possible using, alone or in combination, one or more of the features set forth above or described in detail below.

The phrases “at least one,” “one or more,” and “and/or,” as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B, and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C,” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together.

The term “a” or “an” entity, as used herein, refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more,” and “at least one” can be used interchangeably herein.

The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Accordingly, the terms “including,” “comprising,” or “having” and variations thereof can be used interchangeably herein.

It shall be understood that the term “means” as used herein shall be given its broadest possible interpretation in accordance with 35 U.S.C. § 112(f). Accordingly, a claim incorporating the term “means” shall cover all structures, materials, or acts set forth herein, and all of the equivalents thereof. Further, the structures, materials, or acts and the equivalents thereof shall include all those described in the summary of the invention, brief description of the drawings, detailed description, abstract, and claims themselves.

