ORC Voltage Regulator for DC Bus Stability

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Solution Overview

Problem

Rankine cycle systems, particularly organic Rankine cycle (ORC) systems, face challenges in maintaining a constant voltage on a DC bus without an infinite grid, as they cannot quickly adjust power generation to match load changes due to their large thermal mass and heat transfer times, leading to voltage fluctuations during load variations.

Innovation Solution

The integration of an ORC voltage regulator that diverts excess electrical power from the inverter system back to the electric heater, allowing for rapid adjustments in the heating rate of the organic fluid, thereby maintaining a constant voltage on the DC bus by electronically pulsing the electric heater based on sensed parameters, such as load changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the ORC system uses large thermal mass for heat transfer, then heat transfer efficiency is improved, but the system cannot quickly adjust power generation to match load changes

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidpower generation adjustment speed
Core Design Contradiction:
Use of energy by moving objectVSSpeed

Solution Approach 1:

The heating system is divided into two independent parts: an electric heater for rapid power adjustment and a heat source for baseline heating. This segmentation allows each component to serve its specialized function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electric heater acts as an intermediary device between the electrical grid and the ORC system. It provides a fast-response interface that decouples the slow thermal response of the ORC system from the rapid electrical load changes, enabling independent optimization of both heat transfer efficiency and power adjustment speed.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the ORC system operates without an infinite grid, then remote area power generation is enabled, but voltage fluctuations occur during load variations

Engineering Contradiction:
Improveremote area operation capabilityVSAvoidDC bus voltage stability
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The system continuously monitors DC bus voltage and dynamically adjusts electric heater power consumption based on voltage deviations. This feedback mechanism automatically counteracts voltage fluctuations by modulating the heater's electrical load, thereby stabilizing the DC bus voltage during load variations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The electric heater's power consumption parameter is dynamically changed based on system conditions. By adjusting the heater's electrical power demand, the system can compensate for load variations and maintain voltage stability, enabling reliable off-grid operation.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If excess electrical power is diverted to the electric heater, then DC bus voltage stability is improved, but additional energy conversion is required

Engineering Contradiction:
ImproveDC bus voltage stabilityVSAvoidenergy conversion loss
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The electric heater serves a dual purpose: it provides necessary heat to the ORC system while simultaneously acting as a controllable electrical load to stabilize DC bus voltage. This self-service approach eliminates the need for separate voltage regulation equipment and reduces overall system energy losses.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables the ORC system to quickly respond to both positive and negative load changes, maintaining a stable DC bus voltage within milliseconds to seconds, allowing the system to operate effectively in remote areas without an infinite grid, while also improving efficiency by preheating the working fluid.

Implementation Method 1

The electric heater heats the organic fluid prior to the evaporator

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The evaporator provides a vaporized organic fluid to the turbine

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

evaporation of a working fluid

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 4

a turbine that receives the vapor from the evaporator to drive a generator

Methodology Applied
Scientific EffectHeat engine: Heat Engine

Implementation Method 5

The turbine is coupled to the generator for producing electric power

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 6

a condenser for condensing the vapor

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP2529087B1Organic rankine cycle (ORC) load following power generation system and method of operation
Publication Date: 2018.11.14 NANJING TICA AIR CONDITIONING CO LTD
  • EP2529087B1 patent drawingFigure 1
  • EP2529087B1 patent drawingFigure 2
  • EP2529087B1 patent drawingFigure 3

AI summary

A system for producing power using an organic Rankine cycle (ORC) includes a turbine, a generator, an evaporator, an electric heater, an inverter system and an organic Rankine cycle (ORC) voltage regulator. The turbine is coupled to the generator for producing electric power. The evaporator is upstream of the turbine and the electric heater is upstream of the evaporator. The evaporator provides a vaporized organic fluid to the turbine. The electric heater heats the organic fluid prior to the evaporator. The inverter system is coupled to the generator. The inverter system transfers electric power from the generator to a load. The ORC voltage regulator is coupled to the inverter system and to the electric heater and it diverts excess electrical power from the inverter system to the electric heater.