The Merit-Order Effect of Load-Shifting: An Estimate for the Spanish Market

Renewable producers can offer selling bids with very low marginal cost since they are not obliged to include on any cost related to the use of energy from the wind or sun. Accordingly, when the Market Operator integrates a renewable bid in the merit-order generation curve, all the generators based on conventional technologies, with higher marginal cost due to the cost of fuels, are displaced to the right. The right-shifting of the merit-order generation curve leads to a lower clearing price, a small increment of the traded energy (almost inelastic demand curve), and a reduction of the total cost of the energy traded in the wholesale market. This is the key mechanism of the well-known merit-order effect of renewables. Load-shifting (demand-side management) plans are expected to yield a reduction of the cost of the traded energy for the customers, since the cost-saving due to the energy eschewed at peak hours would be greater than the extra cost due to the increased demand at off-peak hours. This work will show that the main effects of load-shifting on the market are qualitatively similar to that of renewables, which exemplify the existence a “merit-order effect of load-shifting”. To analyse the characteristics of the merit-order effect of load-shifting, a simplified model has been developed, based on the displacement of the generation and demand curves. A set of scenarios has been generated in order to quantify the main effects on the Spanish/Iberian market for 2015.Ministerio de Economía y Competitividad, España (Ministry of Economy and Competitiveness, Spain) grant ENE2016-77650-

Influencia de la integración de la generación renovable y la gestión de la demanda en el mercado

Los principales efectos de la integración de la producción renovable en el mercado están ampliamente estudiados en la literatura, sin embargo, apenas se ha dedicado esfuerzo investigador al análisis de los efectos de las medidas de gestión de la demanda y el almacenamiento. Este trabajo trata de mitigar esta carencia analizando los efectos en el mercado mayorista de la energía eléctrica de tres tipos de actuaciones: • Integración de renovables, que servirá como base de comparación • Gestión de la demanda - ahorro y eficiencia energética y - desplazamiento temporal de cargas • Almacenamiento de energía - desde la generación (centrales de bombeo) y - del lado de la demanda (baterías). La fuente de información utilizada como referencia en este trabajo son las curvas horarias de generación y demanda (ofertadas y casadas) correspondientes al mercado español/ibérico durante el periodo 2008-2015 (70128 casaciones horarias), obtenidas del archivo histórico del Operador del Mercado (OMIE). A partir de ellas se han elaborado escenarios realistas de integración de renovables, de la gestión o respuesta de la demanda y el almacenamiento, a fin de estudiar sus efectos en el mercado. Con este propósito se ha desarrollado primero un sencillo modelo cualitativo, basado en la linelización del mercado en torno al punto de operación, con el que se han podido establecer algunas hipótesis sobre el potencial impacto de cualquiera de estas medidas en el mercado, especialmente las variaciones en la energía y precio casados. A partir del bien conocido efecto de ordenación por mérito de las renovables, este modelo cualitativo se ha utilizado también para describir y establecer lo que podría denominarse efecto de ordenación por mérito de la gestión de la demanda (ahorro energético y desplazamiento temporal de la demanda) y el almacenamiento (tanto desde la generación como desde la demanda). Posteriormente se ha utilizado el que se ha denominado procedimiento de desplazamiento y continuación de las curvas de generación y demanda, desarrollado para este trabajo, que permite simplificar el proceso de optimización del bienestar global (welfare) que conduce a la determinación del punto de equilibrio del mercado (energía y precio casados), la tarea más exigente en cuanto a tiempo de cómputo para el operador del mercado. Con este método se ha llevado a cabo un reanálisis de los datos históricos del mercado español/ibérico desde 2008 a 2015, incorporando las particularidades concretas de los escenarios considerados. Una vez analizado el efecto en el mercado, se estudiaran otro tipo de efectos más generales sobre el sistema eléctrico, los agentes del mercado o el medioambiente, como pueden ser las variaciones en el volumen de emisiones de CO2, las pérdidas técnicas en el sistema de transporte, la cuantificación económica del efecto de ordenación por mérito y de las primas neutras (cuando proceda), así como las transferencias de renta entre los diversos agentes participantes: generadores convencionales y renovables, consumidores, y posibles terceras partes (almacenamiento). El método cualitativo propuesto, basado en la linealización del mercado en torno al punto de casación real, ha permitido establecer una primera evaluación cualitativa del efecto esperable en el mercado de la adopción de cualquier política que conduzca a cualquier clase de variación de la oferta de compra y/o de venta. En esta estimación, las variaciones en las pendientes de las curvas de generación y demanda juegan un papel muy importante. Por todo ello puede decirse que es un instrumento aproximado, pero muy sencillo y rápido de utilizar, lo que lo hace útil como herramienta de análisis preliminar. Esta herramienta ha permitido identificar efectos de mérito ordenado (merit-order effect), aún no descritos en la literatura, asociados al ahorro o eficiencia energética, al desplazamiento temporal de las cargas y el almacenamiento, tanto desde la generación (bombeo) como desde la demanda (baterías). Resulta especialmente destacable el hecho de que haya sido capaz de predecir un ahorro de energía neto cada vez que se realiza un ciclo de desplazamiento temporal de la demanda, resultado tampoco descrito en la literatura. También ha permitido describir el almacenamiento en la demanda (baterías) como una forma de realización del desplazamiento de la carga, sin tener que alterar la programación de la producción de la planta industrial, pero con unos costes de inversión en la batería y un coste de operación, derivado de las pérdidas en el ciclo de carga-descarga. También ha permitido describir el almacenamiento en la generación como una variante de desplazamiento de la carga. Por otra parte, la metodología de continuación y desplazamiento de curvas, propuesta en este trabajo, ha permitido hacer frente al estudio de escenarios plurianuales en tiempos de cómputo abordables, superando los casi impracticables tiempos de cómputo resultantes de la utilización de la metodología Euphemia. Por otra parte, siempre que las variaciones de energía consideradas en los escenarios sea pequeña en comparación con la energía casada en el escenario real de base, no cabe esperar grandes errores derivados del método propuesto, ya que las variaciones se producirán únicamente en las últimas unidades eliminadas o añadidas de las lista de las realmente casadas en el escenario real de partida, que incluye centenares de unidades de compra y venta. Este método de continuación y desplazamiento de curvas ha permitido confirmar, en líneas generales, las hipótesis establecidas con el método cualitativo, basado en la linealización. Ha permitido una cuantificación más precisa de los efectos de ordenación por mérito (merit-order effect) correspondientes al ahorro o eficiencia energética, al desplazamiento de temporal de la carga, al bombeo y al almacenamiento, tanto desde la generación (bombeo) como desde la demanda (baterías). También ha permitido confirmar el ahorro neto de energía que se produce en cada ciclo de desplazamiento temporal de la demanda.The main effects of the integration of renewable generation on the electricity wholesale market are widely studied in the literature, however, hardly any research effort has been devoted to the analysis of the effects of demand management or storage. This work tries to mitigate this lack by analyzing the effects in the wholesale market of three types of activities: • Integration of renewable generation, that will be used as a reference for comparison • Demand managment (demand response) - Efficiency and energy saving - Load-shifting • Energy storage - From the generation side (pumping hydropower) - From the demand side (bateries). In this work, the source of information used as reference are the hourly generation and demand curves (offered and cleared) corresponding to the Spanish/Iberian market during the period 2008-2015 (70128 hourly cleared prices), retrieved from the historical archive of the Market Operator OMIE). From these, realistic scenarios of integration of renewables, demand management (demand response) and energy storage have been elaborated, in order to study their effects in the market. With this purpose, first, a simple qualitative model, based on the linearization of the market around the point of operation, has been developed. This qualitative model has lead to the establishment of some hypotheses about the potential impact of any of these actions in the market, especially the variations in energy traded and clearing price. This qualitative model has also been used to describe and establish what could be called the merit-order effect of demand management (energy saving and loadshifting) and storage (generation and demand). Subsequently, what has been called the displacement and continuation of the generation and demand curves, developed for this work, has been introduced. This method allows simplifying the process of optimization of the global welfare (welfare) that leads to the determination of the equilibrium point of the Market (traded energy and cleared price), the most demanding task in terms of computation time for the market operator. A reanalysis of the historical data of the Spanish/Iberian market from 2008 to 2015, incorporating the particular particularities of the considered scenarios, has been carried out with this method. Once the effect on the market has been analyzed, other more general effects on the power system, market agents or the environment, such as variations in the volume of CO2 emissions, technical losses in the transmission system, economic quantification of the merit-order effect and neutral premiums (where applicable), as well as income transfers between the various players involved: conventional and renewable generators, consumers, and possible third parties (storage). The proposed qualitative method, based on the linearization of the market around the real marking point, has allowed establishing a first qualitative evaluation of the expected effect in the market of the adoption of any policy that leads to any kind of variation of the purchase and/or sale bids. In this estimation, the variations in the slopes of the generation and demand curves play a very important role. As a result it can be said that it is an approximate instrument, but very simple and fast to use, which makes it useful as a preliminary analysis tool. This tool has lead to identify merit-order effects, not yet described in the literature, associated with energy saving or efficiency, the load-shifting and energy storage (generation and demand). Particularly noteworthy is the fact that it has been able to predict a net energy saving after a cycle of load-shifting, a result still not described in the literature. It has also made it possible to describe the storage on the demand side (batteries) as form of carry out the load-shifting, without having to alter the scheduling of the production of the industrial plant, but with an investment cost in the battery and a operation cost, derived from the losses in the charge-discharge cycle. It has also allowed describing the storage in the generation side as a variant of load-shifting. The methodology of continuation and displacement of curves, proposed in this work, has made it possible to face the study of multiannual scenarios in affordable computation times, surpassing the almost impracticable computation times resulting from the use of the Euphemia methodology. On the other hand, whenever the energy variations considered in the scenarios are small compared to the traded energy in the base (actual) scenario, we can not expect large errors derived from the proposed method, since the variations will occur only in the last units removed or added from the list of the actually cleared in the base real scenario, which includes hundreds of units of purchase and sale. The method of continuation and displacement of curves has allowed confirming, in general lines, the hypotheses established with the qualitative (linear) method. The method has allowed for a more precise quantification of the merit-order effect corresponding to the energy saving or efficiency, the load-shifting, and the storage, both from generation (pumping) and from load (batteries). It has also allowed confirming the net energy saving that occurs in each cycle of loadshifting.Premio Extraordinario de Doctorado U

Assessing the decarbonisation effect of household photovoltaic self-consumption

Article number 128501The combination of falling renewable technology costs, with high and rising electricity prices and non-obstructive national regulations are making distributed generation increasingly attractive. In the case of photovoltaic (PV) systems, even domestic consumers find it profitable to self-produce part of their electricity demand, instead of purchasing all their energy from the grid, which is changing the current way of obtaining and consuming electricity. The purpose of this work is to estimate the decarbonisation effect in the Iberian/Spanish market, produced by domestic PV self-consumption, once the new regulation, passed in 2019, has removed the previous regulatory barriers in Spain. To achieve this goal, the nationwide, distributed, domestic PV self-production was turned into a reduction of the aggregate demand in the market, and the new clearing point and the corresponding dispatched generators list was established, by emulating the performance of the market operator. Based on 2016–2019 market data, the results suggest that self-consumption could decarbonise the Iberian electricity market, with an average rate of just over 300 tCO2-eq/year for each GWh/year of household PV self-consumed energy.Consejeria de Economia y Conocimiento 718RT0564Consejeria de Economia y Conocimiento US-1265887Centro de Desarrollo Industrial y Tecnológico de España CER-20191019Feder (UE) ENE2016-77650-

A Low-Cost Non-Intrusive Method for In-Field Motor Speed Measurement Based on a Smartphone

Induction motors are broadly used as drivers of a large variety of industrial equipment. A proper measurement of the motor rotation speed is essential to monitor the performance of most industrial drives. As an example, the measurement of rotor speed is a simple and broadly used industrial method to estimate the motor’s efficiency or mechanical load. In this work, a new low-cost non-intrusive method for in-field motor speed measurement, based on the spectral analysis of the motor audible noise, is proposed. The motor noise is acquired using a smartphone and processed by a MATLAB-based routine, which determines the rotation speed by identifying the rotor shaft mechanical frequency from the harmonic spectrum of the noise signal. This work intends to test the hypothesis that the emitted motor noise, like mechanical vibrations, contains a frequency component due to the rotation speed which, to the authors’ knowledge, has thus far been disregarded for the purpose of speed measurement. The experimental results of a variety of tests, from no load to full load, including the use of a frequency converter, found that relative errors on the speed estimation were always lower than 0.151%. These findings proved the versatility, robustness, and accuracy of the proposed method.Spanish MEC-Ministerio de Economía y Competitividad (Ministry of Economy and Competitiveness), co-funded by the European Commission (ERDF-European Regional Development Fund) ENE2016-77650-RMinisterio de Ciencia e Innovación (España) CERVERA research program of CDTI (Industrial and Technological Development Centre of Spain) research Project HySGrid+ CER-2019101

A coordinated control of offshore wind power and bess to provide power system flexibility

Article number 4650The massive integration of variable renewable energy (VRE) in modern power systems is imposing several challenges; one of them is the increased need for balancing services. Coping with the high variability of the future generation mix with incredible high shares of VER, the power system requires developing and enabling sources of flexibility. This paper proposes and demonstrates a single layer control system for coordinating the steady‐state operation of battery energy storage system (BESS) and wind power plants via multi‐terminal high voltage direct current (HVDC). The proposed coordinated controller is a single layer controller on the top of the power converter‐based technologies. Specifically, the coordinated controller uses the capabilities of the distributed battery energy storage systems (BESS) to store electricity when a logic function is fulfilled. The proposed approach has been implemented considering a control logic based on the power flow in the DC undersea cables and coordinated to charging distributed‐BESS assets. The implemented coordinated controller has been tested using numerical simulations in a modified version of the classical IEEE 14‐bus test system, including tree‐HVDC converter stations. A 24‐h (1‐min resolution) quasi-dynamic simulation was used to demonstrate the suitability of the proposed coordinated control. The controller demonstrated the capacity of fulfilling the defined control logic. Finally, the instan-taneous flexibility power was calculated, demonstrating the suitability of the proposed coordinated controller to provide flexibility and decreased requirements for balancing power

The Merit-Order Effect of Energy Efficiency

The integration of certain amount of renewable generation in the wholesale market right-shifted the merit-order generation curve, which produces a noticeable reduction of the clearing price while slightly increases the traded energy (almost inelastic demand curve). The downward pressure on the clearing price is mainly due to the fact that the introduction of renewable generation bids with very low (even null) marginal cost, displaces to the right all kinds of conventional technologies (with higher marginal cost), including the technology which would otherwise have set the clearing market price. This right-shifted displacement of the merit-order generation curve leads to a lower wholesale clearing price, a small increment of the traded energy and a reduction of the total cost of the traded energy in the wholesale market. This is the key mechanism and its main effects on the market of the very well-known meritorder effect of the renewables. The promotion of energy-efficiency plans (industry and domestic) by policy-makers is expected to yield a reduction of the demand. As a result of the reduction of demand bids, the merit-order demand curve would experience a left-sifted displacement, which would produce a reduction of both the clearing price and the amount of traded energy. Consequently, the total cost of the traded energy also would diminish. As can be seen, the parallelism of the main effects on the market between the integration of renewable and energy efficiency evidences the existence of what can be called the merit-order effect of energy efficiency. To analyze the characteristics of this merit-order effect of the energy efficiency, a simplified model, based on the linearization of the market around the clearing point, is developed. This simplified model is also used to compare the merit-order effect of energy efficiency and renewables. A set of scenarios with energy efficiency and renewables have been generated in order to quantify the main effects on the Spanish/Iberian market for the year 2014

Renewables versus efficiency. A comparison for Spain

Along the last decades, renewable energy (especially wind) in Spain has undergone a significant development (lead by a small group of renewable promoters supported by institutional policies), contributing significantly to electric generation mix (42.8% renewable in 2014). On the contrary, the promotion of energy efficiency actions (accomplished by a large number of industrial and domestic consumers that are very poorly supported by energy policies), are still little explored. According to ODYSSEE-MURE, energy efficiency at the EU-28 level improved by 1.2%/year on average from 2000 to 2013, while for the case of Spain, the rate of improvement was only 0.6 %/year on average throughout that period (the lowest rate of energy efficiency improvement in the EU-28). This work seeks to compare the integration of renewable production with energy efficiency plans, in order to advance their potential economic impact in the wholesale market and consumers. To reach that goal, the hourly market data retrieved from the Spanish/Iberian Market Operator (OMIE) for 2014 will be used as a base. Then, a set of pseudoheuristic scenarios with integration of renewable production and energy efficiency (load saving) will be elaborated and analyzed to quantify what are expected to be the main effects on the Spanish electricity market and consumers. The results will show that energy efficiency exhibits the best performance in terms of economic efficiency (less cost of the traded energy) and environmental sustainability (greater replacement of fossil fuels).Ministerio de Economía y Competitividad PCIN-2015-043Ministerio de Economía y Competitividad ENE2015-69597-RMinisterio de Economía y Competitividad ENE2014-54115-

Measurement of the Speed of Induction Motors Based on Vibration with a Smartphone

Induction motors are key pieces of equipment in today’s society, powering a variety of industrial drives and home appliances. The induction motor speed is often used to monitor the performance of all kinds of industrial drives. For example, in the industrial field, the motor speed is very often used to determine the efficiency and mechanical load of motors. In this work, a new simple, low-cost, and nonintrusive procedure is proposed for infield measurement of induction motors speed, which is based on the spectral analysis of the vibration signal of the motors. The motor vibration signal is first acquired using the accelerometers integrated into a basic phone. The acquired signal is then treated by a MATLAB-based algorithm, which can determine the motor speed by identifying the mechanical frequency of the rotor shaft from the harmonic content of the vibration signal. In this way, it is shown that the mechanical frequency corresponding to the speed of rotation of the motors can be acquired by means of the embedded accelerometers of a common smartphone, avoiding the acquisition and installation of external accelerometers. To the authors’ knowledge, this could be the first time that a smartphone has been proposed as a practical means of measuring the speed of a motor by analysing its vibration. Experimental results from an extensive set of tests, including the supply of the motor from a frequency converter, show that the speed can always be measured with a relative error of less than 0.15%.Ministerio de Economía y Competitividad ENE2016-77650-RCYTED Network Program 718RT0564CERVERA research program of CDTI Project HySGrid CER-20191019Project I+D+i FEDER Andalucía 2014-2020 US-126588

Cross-Border Energy Exchange and Renewable Premiums: The Case of the Iberian System

In 2002, the European Union set a target of 10% electricity interconnection capacity for 2020: a target that has been further extended to 15% by 2030. Cross-border interconnection of regional/national electricity systems will allow the EU to enhance its security of supply and to integrate more renewables into energy markets. Although the EU has a common renewable directive, every Member State has its own renewable support policy. For the case of Spain, consumers pay the renewable premium in their electricity bills; however, consumers would not be overburdened if premiums were counter-balanced with the energy-cost reduction due to the merit-order effect of renewables. When two markets are interconnected, the energy exchange through the interconnection yields certain expected rent transfers due to the market rules. However, this exchange is also accompanied by other unforeseen rent transfers related to the regional/national policies on renewables. To the authors’ knowledge, the identification and quantification of these indirect rent transfers has not been previously addressed. This paper analyses and quantifies how the premiums on regional/national renewables are distributed between neighbouring countries through cross-border exchanges. The analysis focuses on the Iberian/Spanish system and its neighbours, although the methodology could be extended to other systems. To this end, data on the market and premiums has been considered, as well as the exchanges between France, Spain, Portugal, and Morocco, for the years 2015–2017. The main finding of this work is that the Spanish system, due to the lack of a coordinated/harmonized renewable premium policy, has been “importing” about 40 M€/year of renewable premium from France and 17 M€/year from Portugal while “exporting” about 66 M€/year towards the Moroccan systemsMinisterio de Economía y Competitividad PCIN-2015-043Ministerio de Economía y Competitividad ENE2016-77650-RComisión Europea (FEDER — European Regional Fondo de Desarrollo) PCIN-2015-043Comisión Europea (FEDER — European Regional Fondo de Desarrollo) ENE2016-77650-RComisión Europea (FEDER — European Regional Fondo de Desarrollo) SI-1778/12/201

Investigation of inertia response and rate of change of frequency in low rotational inertial scenario of synchronous dominated system

The shift to a sustainable energy future is becoming more reliant on large-scale deployment of renewable and distributed energy resources raising concerns about frequency stability. Rate of Change of Frequency (RoCoF) is necessary as a system inertia metric in order for network operators to perform control steps to preserve system operation. This paper presents in a straightforward and illustrative way several relevant aspects of the inertia response and RoCoF calculation that could help to understand and explain the implementation and results of inertial response controllers on power converter-based technologies. Qualitative explanations based on illustrative numerical experiments are used to cover the effects on the system frequency response of reduced rotational inertia in synchronous dominated power systems. One main contribution of this paper is making evident the importance of the governor action to avoid the synchronous machine taking active power from the system during the recovering period of kinetic energy in an under frequency event