CN105474496A - Adaptive ac and/or dc power supply - Google Patents

Abstract

Embodiments of an adaptive power supply for accommodating instances in which power is generated too much for load demand and instances in which power is generated too little for load demand are disclosed.

Description

Adaptive AC and/or DC power supply

technical field

The present disclosure relates to power generation circuits for use with electric power systems with or without renewable energy sources, which can sometimes vary in availability.

Background technique

In traditional power systems, power generation companies generate electrical energy to power load centers in a centralized and unidirectional manner. In general, the basic "load following" control method involves the arrangement in which electricity generation follows energy demand. Therefore, a balance between power generation and power demand (eg, "load") can be employed to achieve a stable power generation system. However, given the increasing use of distributed renewable energy sources, such as wind and solar energy, less centralized and dynamic power generation systems can emerge. For example, renewable energy can be installed in a distributed fashion, where the actual location of solar and/or wind capacity is unknown to the utility. Therefore, the power company may not be able to accurately determine total power generation, especially in view of geographically varying wind speeds, cloud cover, etc. While generation and loads can be moderated by temporary energy storage facilities, such as reservoirs for storing potential energy, and/or chemical energy storage facilities, such as batteries, these solutions can be problematic. For example, chemical storage can be cost-prohibitive. In another example, a water reservoir used for potential energy storage may be susceptible to geographic constraints.

Description of drawings

The claimed subject matter is particularly pointed out and distinctly claimed at the concluding portion of the specification. The claimed subject matter, together with its objects, features and/or advantages, may be better understood by reference to the following detailed description when read in conjunction with the accompanying drawings in which:

Figure 1a shows a simplified control schematic diagram of a series reactive power compensator for output voltage support in transmission according to an embodiment.

Fig. 1 b shows a simplified control schematic diagram of a series reactive power compensator as a central dimming system based on a power inverter circuit according to an embodiment.

Fig. 1c shows a simplified control schematic diagram of a series reactive power compensator as an electric spring according to an embodiment.

Fig. 2 shows a single-phase version of an electric spring based on a half-bridge power inverter and a low-pass inductor-capacitor filter and an Undeland snubber circuit according to an embodiment.

Fig. 3a shows a schematic diagram of a single phase power system according to an embodiment.

Figure 3b shows a schematic diagram of a single phase power system including the use of electric spring circuits according to an embodiment.

Fig. 4 shows a single-phase electric spring for a three-phase system according to an embodiment.

Fig. 5 shows a three-phase electric spring according to an embodiment.

Fig. 6 shows an adaptive power supply for a single phase system according to an embodiment.

Fig. 7 shows an adaptive power supply for a three-phase system according to an embodiment.

Fig. 8 shows an electric spring installed on the high voltage side of a step-down transformer according to an embodiment.

Fig. 9 shows another adaptive power supply according to an embodiment.

Figure 10 shows an adaptive DC power supply according to an embodiment.

Figure 11 shows an adaptive DC power supply set up with a standard power outlet, according to an embodiment.

Figure 12 shows an adaptive AC and/or DC power supply forming part of the power supply infrastructure, according to an embodiment.

Figure 13 shows a DC bus power supply according to an embodiment.

Figure 14 shows the setup of a future power supply according to an embodiment.

Figure 15 illustrates an accessible mechanism for changing input voltage references by external parties, such as utilities and authorities, according to an embodiment.

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and like numerals may designate like parts throughout to indicate corresponding or analogous elements. For simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, it is to be understood that other embodiments may be utilized and structural and/or logical changes may be made without departing from the scope of the claimed subject matter. It should also be noted that directions and references (such as, for example, up, down, top, bottom, over, above, etc.) may be used to facilitate discussion of the figures and are not intended to limit the application of the claimed subject matter. Accordingly, the following detailed description is not to be taken in a limiting sense and the scope of claimed subject matter is intended to be defined by the appended claims and their equivalents.

detailed description

In the following detailed description, numerous specific details are set forth to provide a thorough understanding of claimed subject matter. It will be understood, however, by those skilled in the art that claimed subject matter may be practiced without these specific details. In other instances, methods, apparatuses or systems that would be known by one of ordinary skill have not been described in detail so as not to obscure claimed subject matter.

Reference throughout this specification to an embodiment, an implementation, an example, an example, etc. may mean that a particular feature, structure, or characteristic described in connection with a particular embodiment or example may be included in the claimed subject matter. In at least one embodiment or example. Thus, the appearances of such phrases in various places throughout this specification are not necessarily intended to refer to the same embodiment or to any one particular embodiment described. Furthermore, it is to be understood that particular features, structures, or characteristics that have been described may be combined in various ways in one or more embodiments. In general, these and other issues may of course vary with the particular situation. Thus, the specific context in which these terms are described or used can provide helpful guidance as to the inferences to be drawn for that specific context.

Similarly, the terms "and", "and/or" and "or" as used herein may include various meanings which again will depend at least in part on the context in which these terms are used. Typically, "and/or" and "or" if used in relation to a list such as A, B, or C, are intended to mean A, B, or C (used here in an exclusive sense) as well as A, B, and C. Furthermore, the term "one or more" as used herein may be used to describe any feature, structure or characteristic in the singular or may be used to describe some combination of features, structures or characteristics.

Embodiments may include various demand-side power management methods. A literature review for the period 2005 to 2012 shows that demand side (e.g. load) management (or sometimes called demand response) [1], [2] can be broadly summarized as:

·Delay tolerable power demand task scheduling[3-5]

Use of energy storage to mitigate peak demand [6]

·Real-time pricing[7-9]

· Direct load control or on-off control of smart loads[10-12]

While the methods identified above may have certain advantages, at least some of the methods may suffer from certain limitations. For example, while it may be practical to schedule power demand in advance by day or even hour, responding to real-time power fluctuations may be more problematic. Furthermore, while energy storage may represent one or more relatively advantageous solutions, the use of batteries may be relatively expensive. Also, such solutions as the use of cisterns (where water is pushed up for later conversion from potential energy to electrical energy), such solutions may be more practical in mountainous areas but less practical in low lying areas. In other instances, for example, real-time pricing may be relatively effective in dampening the electricity demand of a large number of price-sensitive consumers, but may not be suitable for ordinary household consumers.

Under certain circumstances, a power company may employ direct load control to shed electrical loads to avoid power system collapse. However, such a centralized control strategy may not be efficient for use with future grids that may include relatively decentralized and intermittently available renewable energy sources that provide electrical energy at the input side of the distribution network. Although on-off control of electrical loads such as water heaters and air conditioners has been proposed, such methods can be overly invasive and cause considerable inconvenience to consumers. Recent work based on wide-area measurements of real-time tracking of node voltage levels (eg for central and regional control of distributed areas by data centers) has been examined. Such real-time tracking of node voltage levels is typically based on information and communication technologies (ITC), such as wireless communication, satellite synchronization, and Internet/Intranet control. In some instances, this approach may be effective under normal operating conditions, but may be more difficult to implement during weather emergencies or during unfavorable atmospheric conditions, such as severe solar storms, where the wireless communication system fails. In other instances, use of Internet infrastructure may also be undesirable, for example due to hacking of servers involved in reporting node voltage levels.

Recent innovations in load response can be related to the development of "electric springs" [13], [14]. The electric spring may include circuitry for a power electronics-based power controller employing "input voltage control" for regulating the supply voltage of the power system. In this particular context, it should be understood that the term requirement is intended to refer to an electronic load and the use of the term requirement throughout should be interpreted in a manner consistent with such understanding. Similarly, the term control is intended to mean at least partially controlling and/or being at least partially adjustable. Again, use of the term control throughout should be interpreted in a manner consistent with such understanding. Likewise, the term "based on" (such as descriptions that X is "based on" Y or that X may be "based on" Y) is intended to indicate that X is or may be based at least in part on Y; however, there may also be Other factors or considerations that have been expressly stated. Again, use of the term "based on" throughout should be interpreted in a manner consistent with such understanding.

Since power inverter circuits are commonly used in power system applications, it can be useful to determine the difference between input and output control methods. For example, Fig. 1a shows a simplified control schematic diagram of a ( _VO regulated) series reactive power compensator for output voltage support in transmission, and Fig. 1b shows a power inverter circuit based as a centrally regulated Simplified control schematic of the (V _O regulated) series reactive power compensator of the optical system. In Figures 1 and 2, the direction of active power (eg current) flow is highlighted. In Figures 1 and 2, the output (V _O ) refers to the output direction of power flow.

Figure 1c shows a simplified control schematic of a ( _VS regulated) series reactive power compensator as an electric spring. Unlike the examples illustrated in Figures 1a and 1b, the electric spring is controlled with an input voltage, where the input (V _S ) refers to the input of active power flow. For example, an input power terminal may refer to a transmission main (such as a busbar).

In a particular embodiment, the electric spring includes a switched mode power inverter, a low pass filter and an input voltage control for regulating the input AC voltage (typically the node voltage of the local AC mains). A single-phase version of the electric spring based on a half-bridge power inverter and a low-pass inductor-capacitor filter with an Undeland snubber circuit is shown in Fig. 2 . In principle, a circuit such as that of Figure 2 could be able to accommodate both real and reactive power, thus giving the circuit the ability to contribute voltage and frequency stability in the power system, at least in theory. In some embodiments, half-bridge, full-bridge, and multi-level power inverters may form one or more electrical spring circuits. Furthermore, it has been proven in practice that the use of electric springs can allow load demand to follow intermittent generation [14] and also enable reductions in energy storage requirements in power systems [15]. With the combination of droop control [16], electric springs can be distributed on the grid to provide distributed stability support to the grid.

In an embodiment, the use of one or more electrical springs exists on the "demand side". For example, an electrical spring may be associated with a non-critical load, which may be characterized as an electrical load capable of tolerating certain variations in supply voltage. Electric springs can be embedded in appliances such as electric water heaters and/or refrigerators to form smart loads that can adapt to fluctuating power supplies. In the embodiments, we describe an improved concept of electric springs on the "power supply side" and the extension and combination of the electric spring concept to form a "smart power supply". Unlike some implementations of electric springs which may employ eg only "input voltage control", the improved smart power supply may employ "input voltage and/or output voltage" control. Also, for example, an electrical spring may be considered to be associated with a power source as opposed to being associated with an electrical load.

Embodiments may relate to power system infrastructure for AC or DC power supplies that may incorporate electric springs to form one or more adaptive power supplies. One or more embodiments may be described in terms of AC power. Subsequently, adaptive DC power supplies based on one or more similar principles are described.

Figure 3a shows a schematic diagram of a single-phase power system. However, it should be noted that while the transformer symbol used in Figure 3a may indicate a single phase system, in embodiments a multiphase power system may be employed, such as for example a three phase power system. For simplicity, a single phase system is used for illustrative purposes only, and claimed subject matter is not limited in this regard. In Figure 3a, terminal "L" may refer to the "live" terminal and N may refer to the neutral terminal. Standard AC mains, live-to-neutral voltages may refer to phase voltages, which may typically be in the range of 220.0V-240.0V for approximately 50.0Hz power systems and 100.0V-240.0V for approximately 60Hz power systems. 110.0V range. In many countries the power company can regulate the AC mains voltage within a tight tolerance of a certain percentage (eg +/- 6% of the nominal AC mains voltage in Hong Kong). The tolerance for standard AC mains is labeled X% in FIG. 3 .

As shown in Figure 3b, embodiments may include the use of electric spring circuits, which may be based at least in part on an AC to AC power inverter for AC voltage output, and may be used to form an adaptive AC power supply. The "live" terminal of the adaptive AC power supply is called L _adapt .

For single-phase systems, the electric springs may include the half-bridge power inverter circuit shown in FIG. 4 . In other embodiments, full bridge power inverters or other types of power inverters (such as, for example, multi-level power inverters) may be used. The output voltage of the power inverter may be a sinusoidal pulse width modulated (PWM) signal which may be filtered using a low pass filter to generate a controllable sinusoidal voltage as the electric spring voltage. Electric spring power inverters can accommodate reactive power and/or real power. The DC link (DClink) capacitors of the power inverter can provide stored energy which can provide reactive power compensation for regulating node voltages on the AC mains, for example. For reactive power control, the current vector flowing in the load of the adaptive power supply may be at least approximately perpendicular to the voltage vector of the electric spring. Examples of control methods for electric springs for voltage regulation using pure reactive power control can be described in [13]–[16].

If real and reactive power control is determined to be beneficial, a DC power source such as a battery, for example, may be connected in parallel with one or more capacitors or may be used in place of the capacitors in their entirety. The use of power sources has been discussed in [13]. In this instance, for example, the current vector of the load in the adaptive power supply may not be approximately perpendicular to the voltage vector of the electric spring. The mode of operation of such an electric spring with both real and reactive power control has been reported by the inventors in [17].

For a three-phase system, for example, a single-phase electric spring such as that shown in FIG. 4 can be used for one or more phases. In an embodiment, for example, single-phase electric springs may be used for each phase of a three-phase system. An embodiment of a three-phase electric spring circuit is shown in FIG. 5 . A three-phase power inverter with DC link capacitors and/or an active DC voltage source (such as a battery) and a low-pass filter (including inductors and capacitors) form the basic unit of a three-phase electric spring circuit. Via the primary winding of a three-phase transformer X-Y-Z having terminals X1 , Y1 and Z1 , the filtered electric spring voltage can be coupled to three secondary windings having terminals X2 , Y2 and Z2 . The output terminals XX, YY and ZZ may thus form three-phase line voltage output terminals of the three-phase adaptive power supply. Both star-connected loads and delta-connected loads may be connected to a three-phase adaptive power supply such as that shown in FIG. 5 for example. It should be noted that the three-phase transformers could also be replaced by, for example, three single-phase transformers, provided that the connections of the three single-phase transformers are equivalent or at least similar to those shown in FIG. 5 .

Adaptive power supplies based at least partly on the electric spring concept are not limited to eg low voltage power distribution networks, and can be applied, at least in principle, to medium and high voltage power networks. For medium and high voltage applications, e.g., a multi-level power inverter for use at higher voltages (e.g., at a higher rated voltage) may, for example, replace at least part of the two-level power inverter shown in FIG. 5 .

Figure 6 illustrates an adaptive power supply for a single phase system according to an embodiment. Electric springs and input and output control loops are implemented on the low voltage side of the distribution line. A similar principle can be applied to a three-phase power system as shown in FIG. 7 . If desired, electric springs can be mounted on the high voltage side of the step-down transformer as shown in FIG. 8 .

Embodiments differ from previous concepts of electric springs reported in [13]-[16] in at least three respects.

• Regardless of the load type, electric spring circuits can be incorporated (as part of the power supply infrastructure) into the power supply side. In previous reports, the electric spring can be an independent circuit external to the power supply and/or embedded in the appliance.

• Adaptive power supplies can employ both input voltage control and input frequency control (for regulating standard AC mains voltage and reducing frequency instability in the traditional sense of electric springs reported in [13]-[16]). Output voltage control as illustrated in Figure 3b (used to limit the maximum and minimum voltage values of the adaptive AC mains voltage and allow the output AC voltage to vary within the maximum and minimum voltage levels according to input voltage control and input frequency control) .

• The use of an active DC power source, such as a battery, may enable both voltage and frequency control loops to be included in an adaptive power supply system as shown in FIG. 9 .

As shown in the embodiment of Figure 9, for example, there may be four main control blocks in the control scheme. The control block 1 can perform an adaptive voltage regulation function based on input frequency control. The control block 2 can perform an adaptive voltage regulation function based on input voltage control. The control block 3 may perform a reactive power compensation function based at least in part on input power displacement angle control. The control block 4 may perform an overcurrent protection function based at least in part on output current detection.

In an embodiment, the control block 1 may comprise a circuit or other means implementing the method of detecting the frequency f _S of the input voltage V _S . The detected frequency can be compared to the desired frequency f _S(preset) for the input voltage. The difference _Efs between these two frequencies is scaled by a factor _Kf and then passed through a limiter and input into an adder Sum. In the control block 2, a circuit or method of detecting the RMS value of the input voltage (eg V _S,rms ) is adopted. The detected RMS voltage is compared with a preset and/or desired RMS voltage V _{S,rms(preset)} . The difference E _VS,rms of these two voltages can be scaled by a factor K _V and passed through a limiter and input into an adder labeled "Sum". At adder "Sum", the signals from control block 1 and control block 2 can be summed with the desired reference value V _O(preset) of the output voltage to provide an adaptive output voltage reference value of V _O(preset) ±ΔV. The output of Sum may be passed through, for example, a limiter, which may, for example, set one or more limits |V _Oref | of the output voltage reference point not less than V _min and not greater than V _max such that V _min ≤ |V _Oref | ≤ V _max . The values of V _max and V _min may be set and/or may be programmable. Control blocks 1 and 2 can perform functions such as automatic load shedding or load boosting. When the detected _fS is higher than _fS(preset) , which can indicate for example that the power bus (e.g. busbar) is underloaded, the output voltage reference is adaptively adjusted to a higher value such that at L _adapt The regulated output voltage is higher. In some embodiments, a higher L _adapt may result in greater power drawn from the mains for passive loads. This can be reversed for f _S lower than f _S(preset) . At the same time, when the detected V _S,rms is higher than V _{S,rms (preset)} , this can also indicate that the power bus is under-loaded, and the output voltage reference can be adaptively adjusted to a higher value so that at L The regulated output voltage at the _adapt is higher and vice versa.

For example, reactive power compensation can be performed at the control block 3 by detecting the displacement angle between the input voltage V _S(LF) and the input current I _S(LF) . For example, input voltage V _S and input current I _S may be passed through a low-pass filter to preserve their fundamental frequency components (eg, V _S(LF) and I _S(LF) ). The signal can be passed through a phase angle detection circuit/method to obtain a phase angle shift ±θ. A positive angle of +θ may indicate that the input current is leading the input voltage, which may be equivalent or at least similar to the behavior exhibited by capacitive circuits. A negative angle (-θ) may eg indicate that the input current may be lagging the input voltage, eg this may exhibit behavior similar to that of an inductive circuit.

θ can then be compared to the desired displacement angle θ _(preset) , and the difference _Eθ can be passed through a compensator and/or limiter to change the sinusoidal signal sin2πft to sin( 2πft+θ _com ). By varying the angle θ _com , different reactive power compensations can be performed. For power factor correction, the desired phase angle is set to θ _(preset) =0. In the case of +θ, _θcom will be negative, which should cause the electric spring to generate a voltage that creates inductive power to compensate for the capacitive effect of the load. In the case of -θ, _θcom can be a positive value, which should cause the electric spring to generate a voltage that creates capacitive power to compensate for the inductive effect of the load.

The sinusoidal signal varying with sin2πft corresponds to the oscillation frequency of the input voltage V _S and it is obtained through a frequency synchronization circuit using V _S(LF) . The output of the phase delay circuit comprising the signal sin(2πft+θ _com ) can be modulated with the output from the summer/limiter (Sum/Limiter), eg comprising the signal |V _Oref |. This can give an instantaneous output voltage reference for V _Oref which can be used for real-time control of the adaptive output voltage V _O at L _adapt . For voltage feedback control, _VO can be compared to _VOref and the difference can be compensated and limited before being passed into the gate pattern generator for controlling one or more switching actions of the electric spring.

In the control block 4, at least in some embodiments, for example, the load current _IO can be sensed and compared to the value of the maximum allowable current _IO(lim) through a comparator. For example, if an overcurrent or short circuit occurs at the output load such that _Io > Io _(lim) , in response the comparator may toggle an output high signal to reset the flip-flop, thereby turning off the strobe pattern generator. Reset can restart the electric spring.

There are at least three differences between the standard AC mains and adaptive AC mains embodiments:

• Conventional AC mains often employ a tight tolerance of X% for voltage fluctuations. However, an adaptive AC mains can exhibit an output voltage that can be regulated within a wider tolerance with a maximum value (+n% of nominal value) and a minimum value (-m% of nominal value).

• Standard AC mains can be regulated by the power company to fulfill promises to maintain a well regulated supply within tight tolerances. However, when using an adaptive power supply, the output voltage can be adjusted over a wider range of voltages to vary the load power consumption for the load being powered.

• There is no longer a need to distinguish between critical and non-critical loads for the electric spring embodiment. Adaptive power can be based on electric spring technology, which is now part of the power infrastructure. Variable and/or constant electrical loads may be connected to the adaptive power supply provided the load can accommodate varying voltages within the adaptive power supply's maximum and minimum voltage levels.

Essentially, with an embodiment of an adaptive power supply, the intermittent nature of renewable generation can be matched by changes in load demand. This can allow generation to be balanced by load demand. If such a power balance is achieved, the voltage of the standard power supply can be adjusted to the nominal value.

If the total power generation at a moment is lower than the load demand, the voltage of the adaptive power supply can be dynamically reduced in order to reduce the power consumption of the electric load (other than those loads of the constant power type). If the generation is less than the load demand such that the voltage of the adaptive power supply reaches its minimum value, some of the load power can come from the adaptive power supply's energy storage (such as a battery) via an electric spring power inverter. By using input voltage control to regulate the AC mains voltage (such as that of a standard power supply), the voltage of the adaptive power supply can be varied in such a way that the total power consumption of the load using the adaptive power supply can be varied in order to achieve the supplied power and Power balance between power loads.

If at any point in time the generation is greater than the load demand, the adaptive power supply can increase the voltage in such a way that the total power consumption can increase in order to balance the generation or at least reduce the imbalance in the generation. When the maximum adaptive supply voltage level is reached, additional power generation can be shunted to the battery for storage. In this way, a balance between power generation and load demand can still be maintained.

The embodiment of an adaptive AC power supply can be extended to an adaptive DC power supply for DC electrical loads as shown in FIG. 10 . Similar to the AC counterpart, the DC voltage output has maximum and minimum levels that can be set and programmed. For example, for a nominal DC voltage of approximately 48.0V, the maximum level may be n% above approximately 48V and the minimum level may be m% below approximately 48V. The DC voltage variation can be controlled in such a way that the DC load power consumption will balance generation and load demand or reduce the imbalance between generation and load demand. Adaptive DC power supplies can be set up with standard power outlets as shown in FIG. 11 .

Embodiments such as adaptive AC and/or DC power supplies may form part of the voltage infrastructure as shown in FIG. 12 . AC and DC power sources fed by standard AC mains can accommodate the intermittent nature of future grids with high penetration of dynamically changing renewable energy sources. Embodiments provide an adaptive power infrastructure that can satisfy a control paradigm where load demand follows generation - which may be desirable for future smart grids. 13 illustrates a single-phase example of a standard power supply and an adaptive power supply based at least in part on certain embodiments. Electric spring circuits with substantial power consumption typically require the installation of a DC energy storage system, such as a battery storage system. Using certain embodiments, the battery storage system may optionally be replaced by a DC bus power supply, as shown in FIG. 13 .

Figure 14 illustrates an embodiment of the present invention with respect to the setup of future power supplies. It shows that adaptive AC power can be derived from standard AC mains supply. It also demonstrates that the adaptive high voltage DC power supply and the low voltage power supply can also be derived from the same standard AC mains supply.

Descriptions of adaptive power supplies so far based on the use of electric springs have assumed that the electric springs are always operating as individual units. However, it should be noted that these electric springs can also incorporate droop control into the input voltage control loop such that these electric springs can assist adaptive voltage sources to regulate the mains voltage in a coordinated manner - as described in patent application [16] described in.

Furthermore, what is proposed is to provide an accessible mechanism so that the power company or authority can control the reference mains voltage in the control loop of the electric spring in order to provide a new mechanism to control the mains voltage level in different parts of the grid. Voltage control enables utilities to control the mains voltage in different parts of the grid for various purposes. An example is changing the voltage level in order to reduce unnecessary current flow in the distribution network in order to reduce conduction losses. Such an accessible mechanism for changing the input voltage reference by an external party such as a power company or authority is illustrated in FIG. 15 . The voltage reference provided by the external body can be transmitted by wired or wireless mechanisms.

Furthermore, it is also proposed to provide a load setting control mechanism with an output signal so that electricity consumers can use it for automatic control of the amount of electricity used in their smart appliances or smart loads. This mechanism, which may optionally be employed in an adaptive power supply for directly varying load power, is illustrated in FIG. 15 . The control mechanism detects the input frequency and voltage level and determines whether the grid is overloaded or underloaded. It provides an output signal R _set containing information about the loading level available in the grid. Future smart appliances can be designed to adjust its power consumption based on the information provided by R _set . As an example, the load setting control can be integrated with an adaptive power supply with ground to form a four-pin power outlet outlet, as shown in FIG. 13 . Such integration extends to all adaptive power supplies.

Similar to FIG. 9 , there are four main control blocks in the control scheme in FIG. 15 . Here, an optional load setting control block is introduced for performing load power control in smart appliances. Override control of the voltage reference is included in control block 1 and control block 2 . Control block 1 performs an adaptive voltage regulation function based on input frequency control. Control block 2 performs an adaptive voltage regulation function based on input voltage level control. The control block 3 performs the reactive power compensation function based on input power displacement angle control. The control block 4 performs an overcurrent protection function based on output current detection.

In the control block 1, a circuit or method of detecting the frequency f _S of the input voltage V _S is taken. The detected frequency can be compared with a reference frequency f _Sref for the input voltage. The difference _Efs between these two frequencies is scaled by a factor _Kf and then passed through a limiter and input into an adder Sum. Here, the reference frequency f _Sref is typically an internally preset desired frequency f _S(preset) , which is the default frequency of the grid. An override function is included so that if the utility wishes to change the transmission frequency, it can be done by feeding a "true" signal and the new desired frequency reference _fS(ext) to an override block which will then take f _Sref as f _S(ext) .

In the control block 2, a circuit or method of detecting the RMS value of the input voltage (eg V _S,rms ) is adopted. The sensed RMS voltage is compared to a reference RMS voltage V _S,ref . The difference E _VS,rms of these two voltages is scaled by the factor K _V , then passed through the limiter and input into the adder Sum. Here, the reference RMS voltage V _S,ref is typically an internally preset desired RMS voltage V _{S (preset)} , which is the default frequency of the grid. An override function is included so that if the utility wishes to change the transmission voltage, it can be done by feeding a "true" signal and the new desired RMS voltage reference _VS(ext) to an override block which will then assume V _Sref as VS _(ext) .

In the load setting control block both the frequency error E _fs and the RMS voltage error E _VS.rms are scaled by factors K _y and K _x respectively and then passed through a limiter and input into an adder. The output is a signal ±ΔΡ, the positive value of which corresponds to a surplus of grid generation and the negative value corresponds to a shortage of grid generation. The ±ΔΡ is fed to a quantizer which converts the ± _ΔΡ into an output signal Rset of discrete values (for example in the range -2, -1, 0, 1, 2) connected to the Smart appliances have hidden meanings. For example, R _set =-2 may indicate that the smart appliance is operating at its lowest power because there is a shortage of power generation. R _set =-1 means lower power operation of the smart appliance. R _set =0 means normal operation. R _set =1 means higher power operation and R _set =2 means operating the appliance at maximum power.

In the foregoing description, various aspects of the claimed subject matter have been described. For purposes of explanation, specific numbers, systems or configurations are set forth to provide a thorough understanding of the claimed subject matter. It should be apparent, however, to one skilled in the art having the benefit of this disclosure that claimed subject matter may be practiced without the specific details. In other instances, well-known features were omitted or simplified in order not to obscure claimed subject matter. While certain features have been illustrated or described herein, many modifications, substitutions, changes, or equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications or changes as fall within the spirit of the claimed subject matter.

references

[1] P.Palensk and D.Dietrich, "DemandSideManagement: DemandResponse, IntelligentEnergySystems, andSmartLoads, IEEE Transactions on Industrial Informatics, Issue 3, 2011, Volume 7, pages 381-388

[2] I. Koutsopoulos and L. Tassiulas, "Challenges in demand load control for the smart grid", IEEE Networks, Issue 5, 2011, Vol. 25, pp. 16–21

[3] A.Mohsenian-Rad, V.W.S.Wong, J.Jatskevich, R.Schober, A.Leon-Garcia. "AutonomousDemand-SideManagementBasedonGame-TheoreticEnergyConsumptionSchedulingfortheFutureSmartGrid", IEEE Transactions on Smart Grid, 2010 No. 3, Vol. 1, 320 – 331 pages

[4] M.Parvania and M.Fotuhi-Firuzabad, "Demand Response Scheduling by Stochastic SCUC", IEEE Transactions on Smart Grid, Issue 1, 2010, Vol. 1, pp. 89-98

[5] M.PedrasaT.D., Spooner and I.F.MacGill, "Scheduling of DemandSideResources Using BinaryParticleSwarmOptimization", IEEE Transactions on Power Systems, Issue 3, 2008, Vol. 24, pp. 1173-1181

[6] F.Kienzle, P., Ahcin and G.Andersson, "Valuing Investments in Multi-Energy Conversion, Storage, and Demand-Side Management Systems Under Uncertainty", IEEE Transactions on Sustainable Energy, Issue 2, 2011, Volume 2, Pages 194-202

[7] A.J. Conejo, J.M.Morales and L.Baringo, "Real-TimeDemandResponseModel", IEEE Transactions on Smart Grid, Vol. 1, 2010, No. 3, pp. 236-242

[8] A.-H.Mohsenian-Rad and A.Leon-Garcia, "Optimal Residential Load Control with Price Prediction in Real-Time Electricity Pricing Environments", IEEE Transactions on Smart Grid, Issue 2, 2010, Vol. 1, pp. 120-133

[9] A.J.Roscoe and G.Ault, "Supporting high penetration of renewable generation via implementation of real-time electricity pricing and demand response", IET Renewable Power Generation, Issue 4, 2010, Volume 4, pages 369-382

[10] S.C.Lee, S.J.Kim and S.H.Kim, "DemandSideManagementwithAirConditionerLoadsBasedontheQueuingSystemModel", IEEE Transactions on Power Systems, Issue 2, 2011, Vol. 26, pp. 661-668

[11] GC.Heffner, C.A.Goldman and M.M.Moezzi, "Innovative approach to overifying demand response of water heater load control", IEEE Transactions on Power Transmission, Issue 1, 2006, Vol. 21, pp. 388-397

[12] A. Brooks, E. Lu, D. Reicher, C. Spirakis and B. Weihl, "DemandDispatch", IEEE Journal of Power and Energy, Issue 3, 2010, Vol. 8, pp. 20-29

[13] S.Y.R.Hui, C.K.Lee and F.F.Wu, "Power control circuit and method for stabilizing a Power Supply", PCT Patent Application 61/389,489, filed November 4, 2010

[14] S.Y.R.Hui, C.K.Lee and F.Wu, "Electric Springs-A New SmartGrid Technology", IEEE Transactions on Smart Grid, No. 3, September 2012, Vol. 3, 1552-1561

[15] C.K.Lee and S.Y.R.Hui, "Reduction of energy storage requirements for smart grid using electric springs", IEEE Transactions on Smart Grid (in press)

[16] N.Chaudhuri, B.Chaudhuri, C.K.Lee and S.Y.R.Hui, "Control methods for distributed powersystems", UK Patent Application, Application No.: 1206318.6, 2012

[17] S.C.Tan, C.K.Lee and S.Y.R.Hui, "General steady-state analysis and control principle of electric springs with active and reactive power compensations", IEEE Transactions on Power Electronics, No. 8, Vol. 28, pp. 3958-3969.

Claims (22)

1. an adaptive power supply, it comprises the electrical spring adopting input voltage and/or output voltage control.

2. adaptive power supply according to claim 1, wherein said electrical spring comprises power inverter.

3. adaptive power supply according to claim 2, wherein said power inverter is half-bridge power inverter, full bridge power inverter or multiple power levels inverter.

4. adaptive power supply according to claim 2, wherein said power inverter can generate sinusoidal pulse width modulation signal.

5. adaptive power supply according to claim 1, wherein said electrical spring is the single-phase electricity spring for one or more phase.

6. adaptive power supply according to claim 1, wherein said electrical spring is three-phase electricity spring.

7. adaptive power supply according to claim 6, wherein said three-phase electricity spring comprises three-phase power inverter, and described three-phase power inverter comprises:

One or more DC support capacitor;

For receiving the input of DC voltage; And

Low pass filter.

8. adaptive power supply according to claim 6, wherein said three-phase electricity spring can adapt to the load of one or more DC connection or the load of one or more AC connection.

9. adaptive power supply according to claim 1; comprise adaptive voltage scaling device further; described adaptive voltage scaling device comprises input control device and output-controlling device; wherein said input control device may be used for adaptive voltage scaling and reactive power compensation, and described output-controlling device may be used for overcurrent protection.

10. adaptive power supply according to claim 9, wherein said input control device is addressable, to control rail voltage level by external reference, described external reference is transmitted by wired or wireless device.

11. adaptive power supplies according to claim 9, wherein said input control device can detect the phase angle displacement between input voltage and input current.

12. adaptive power supplies according to claim 11, if wherein described phase angle displacement is positive phase angle displacement, then described electrical spring produces voltage via electric inductance power at least in part, so that the capacity effect of compensating load at least in part.

13. adaptive power supplies according to claim 11, if wherein described phase angle displacement is negative phase angle displacement, then described electrical spring produces voltage via Capacitance Power at least in part, so that the inductive effect of compensating load at least in part.

14. adaptive power supplies according to claim 9, wherein said input control device comprises the controll block for controlling to perform adaptive voltage scaling at least in part based on incoming frequency.

15. adaptive power supplies according to claim 9, wherein said input control device comprises the controll block for controlling to perform adaptive voltage scaling based on input voltage.

16. adaptive power supplies according to claim 9, wherein said input control device comprises the controll block for controlling to perform reactive power compensation at least in part based on input power angle of displacement.

17. adaptive power supplies according to claim 9, wherein said input control device comprise at least in part based on electrical equipment bearing power compensate perform the controll block that load arranges control.

18. adaptive power supplies according to claim 9, wherein said output-controlling device comprises the controll block for performing overcurrent protection at least in part based on output electric current measure.

19. adaptive power supplies according to claim 1, if be wherein greater than loading demand at the energy output of a moment, then increase the voltage of adaptive power supply to reduce the imbalance between energy output and load.

20. adaptive power supplies according to claim 1, if be wherein greater than loading demand at the energy output of a moment, are then diverted to one or more chemical storage facilities by a part for energy output.

21. 1 kinds of devices comprising the adaptive power supply according to any one in claim 1-20.

22. according to device described in claim 21, and wherein said adaptive power supply is self adaptation AC power supplies or self adaptation DC power supply.